Difference between Mitochondrial DNA and Chloroplast DNA

Both mitochondrion and chloroplast are semi autonomous organelles with DNA. Majority of proteins required for mitochondrion and chloroplast are coded by genes of the nucleus. Only some proteins are coded by the DNA of mitochondrion and chloroplast. That is why; these organelles are called as semi-autonomous organelles.
Difference between mitochondrial DNA and Chloroplast DNA

Mitochondrial DNA
1. Mitochondrial DNA is called as mt DNA which is double stranded, circular and not covered by a membrane.
2. Size varies between species
· Human mt DNA 16 Kb (16569 bp)
· Plant cell mt DNA 200 kb-2500kb
3. Typically dozens of copies of DNA in each mitochondria
4. Animal mitochondrial genome contains 37 genes that encode 13 proteins, 22 tRNAs, and 2 rRNAs
The 13 mitochondrial genes codes for protein subunits of the enzyme complexes of the oxidative phosphorylation system, which helps mitochondria to act as the powerhouses of our cells.
5. Genes are transcribed in a polycistronic manner- a large mRNA molecule with instruction to make many proteins simultaneously
6. AT (adenine-thymine) rich (65% approx) and lack introns.
· Kinetoplast: In Trypanosomes, each mitochondria contains 1000 of copies of mt DNA arranged into a complex interlinked structure  called Kinetoplast.
Chloroplast DNA
1. Chloroplast DNA is called as ct DNA, cP DNA or plastome
2. Genome size 120-170 kb of DNA
3. Exist in multiple copies
    Each chloroplast with several nucleoid regions containing 8-10 rings of DNA molecules
    The number of DNA copies in mature chloroplast is 15-20.
4. Chloroplast genome include ~100 genes, 46-90 protein coding genes,
    Code for 4 ribosomal RNAs, 21 ribosomal proteins, 4 RNA polymerase subunits and over 30 tRNA genes
    Highly conserved throughput plant species
5.  Majority of genes are transcribed as polycistronic operons
6. Generally, AT rich and lack introns
Similarities between mitochondrial and chloroplast genome
· Both mt DNA and cp DNA are circular, double stranded and not enveloped by a membrane.
· Both mt DNA and cp DNA are devoid of histone proteins
· Both lack introns
· Both are generally AT rich genomes
See the Difference between Mitochondrial DNA and Nuclear DNA
Both mitochondrion and chloroplast are semi autonomous organelles with DNA. Majority of proteins required for mitochondrion and chloroplast are coded by genes of the nucleus. Only some proteins are coded by the DNA of mitochondrion and chloroplast. That is why; these organelles are called as semi-autonomous organelles.
Difference between mitochondrial DNA and Chloroplast DNA

Mitochondrial DNA
1. Mitochondrial DNA is called as mt DNA which is double stranded, circular and not covered by a membrane.
2. Size varies between species
· Human mt DNA 16 Kb (16569 bp)
· Plant cell mt DNA 200 kb-2500kb
3. Typically dozens of copies of DNA in each mitochondria
4. Animal mitochondrial genome contains 37 genes that encode 13 proteins, 22 tRNAs, and 2 rRNAs
The 13 mitochondrial genes codes for protein subunits of the enzyme complexes of the oxidative phosphorylation system, which helps mitochondria to act as the powerhouses of our cells.
5. Genes are transcribed in a polycistronic manner- a large mRNA molecule with instruction to make many proteins simultaneously
6. AT (adenine-thymine) rich (65% approx) and lack introns.
· Kinetoplast: In Trypanosomes, each mitochondria contains 1000 of copies of mt DNA arranged into a complex interlinked structure  called Kinetoplast.
Chloroplast DNA
1. Chloroplast DNA is called as ct DNA, cP DNA or plastome
2. Genome size 120-170 kb of DNA
3. Exist in multiple copies
    Each chloroplast with several nucleoid regions containing 8-10 rings of DNA molecules
    The number of DNA copies in mature chloroplast is 15-20.
4. Chloroplast genome include ~100 genes, 46-90 protein coding genes,
    Code for 4 ribosomal RNAs, 21 ribosomal proteins, 4 RNA polymerase subunits and over 30 tRNA genes
    Highly conserved throughput plant species
5.  Majority of genes are transcribed as polycistronic operons
6. Generally, AT rich and lack introns
Similarities between mitochondrial and chloroplast genome
· Both mt DNA and cp DNA are circular, double stranded and not enveloped by a membrane.
· Both mt DNA and cp DNA are devoid of histone proteins
· Both lack introns
· Both are generally AT rich genomes
See the Difference between Mitochondrial DNA and Nuclear DNA
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Difference between Mitochondrial DNA and Nuclear DNA

Difference between Mitochondrial and Nuclear genome
1. Mitochondrial DNA or mt DNA is double stranded and circular.
Nuclear DNA is double stranded and linear.
Difference between Mitochondrial and Nuclear DNA
2. Mitochondrial DNA is not enveloped by a membrane.
Nuclear DNA or genome is enveloped by nuclear membrane.
3. In Humans, the mitochondrial genome size is 16,569 DNA base pairs.
Nuclear genome is made of 3.3 billion DNA base pairs.
4. Each mitochondrion contains dozens of copies of mt DNA. Several mitochondria in a cell accounts for 1000 of copies of mt DNA per cell.
Only one copy of nuclear genome per cell.
5. The mitochondrial genome contains 37 genes that encode 13 proteins, 22 tRNAs, and 2 rRNAs.
Nuclear genome has 20,000-25,000 genes including mitochondrial genes.
6. Mitochondrion is a semi-autonomous organelle as majority of proteins required are coded by nuclear genes.
Nuclear genes codes for all proteins required for its function.
7. Generally introns or non coding sequences are absent in mitochondrial DNA.
Nuclear genome has introns or non-coding DNA and accounts for 93% of total DNA.
8. Some mitochondrial coding sequences (triplet codons) do not follow the universal codon
pattern, when they are translated into proteins. Examples: In mitochondrion, AUA codes for methionine (not Isoleucine) and UGA codes for tryptophan (not a stop codon as in mammalian genome).
9. Transcription of mitochondrial genes is polycistronic, an mRNA formed with sequences coding for many proteins.
Transcription of nuclear genes is monocistronic, an mRNA with sequence coding for a single protein.
10. The mitochondrial mode of inheritance is maternal. Therefore mitochondrial associated diseases are inherited maternally.
The nuclear genome is inherited equally from both parents.
See the Difference between mitochondrial DNA and chloroplast DNA 
Difference between Mitochondrial and Nuclear genome
1. Mitochondrial DNA or mt DNA is double stranded and circular.
Nuclear DNA is double stranded and linear.
Difference between Mitochondrial and Nuclear DNA
2. Mitochondrial DNA is not enveloped by a membrane.
Nuclear DNA or genome is enveloped by nuclear membrane.
3. In Humans, the mitochondrial genome size is 16,569 DNA base pairs.
Nuclear genome is made of 3.3 billion DNA base pairs.
4. Each mitochondrion contains dozens of copies of mt DNA. Several mitochondria in a cell accounts for 1000 of copies of mt DNA per cell.
Only one copy of nuclear genome per cell.
5. The mitochondrial genome contains 37 genes that encode 13 proteins, 22 tRNAs, and 2 rRNAs.
Nuclear genome has 20,000-25,000 genes including mitochondrial genes.
6. Mitochondrion is a semi-autonomous organelle as majority of proteins required are coded by nuclear genes.
Nuclear genes codes for all proteins required for its function.
7. Generally introns or non coding sequences are absent in mitochondrial DNA.
Nuclear genome has introns or non-coding DNA and accounts for 93% of total DNA.
8. Some mitochondrial coding sequences (triplet codons) do not follow the universal codon
pattern, when they are translated into proteins. Examples: In mitochondrion, AUA codes for methionine (not Isoleucine) and UGA codes for tryptophan (not a stop codon as in mammalian genome).
9. Transcription of mitochondrial genes is polycistronic, an mRNA formed with sequences coding for many proteins.
Transcription of nuclear genes is monocistronic, an mRNA with sequence coding for a single protein.
10. The mitochondrial mode of inheritance is maternal. Therefore mitochondrial associated diseases are inherited maternally.
The nuclear genome is inherited equally from both parents.
See the Difference between mitochondrial DNA and chloroplast DNA 
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Difference between Compression Wood and Tension Wood

Environmental factors like wind, gravity may induce production of wood with special features, properties or growth patterns. The wood thus formed on leaning trunks or branches by the environmental stress is called as reaction wood.
Reaction wood are of 2 types
1. Compression wood
2. Tension wood
Compression wood and tension wood
1. Compression wood:
1. It is the reaction wood of conifers which develops on the lower side of leaning trunk or branch
2. It is formed by the increases cambial activity on the lower side of the branch
3. It is 15-40% heavier than the normal wood and is rich in lignin
4. Formed in conifers like Pinus

2. Tension wood:
1. It is the reaction wood of dicots which develops on the upper side of leaning trunk or branch
2. It is formed by the increases cambial activity on the upper side of the branch
3. It is rich in cellulose and gelatinous fibres
4. Formed in dicots like Mango tree, Acacia etc
Environmental factors like wind, gravity may induce production of wood with special features, properties or growth patterns. The wood thus formed on leaning trunks or branches by the environmental stress is called as reaction wood.
Reaction wood are of 2 types
1. Compression wood
2. Tension wood
Compression wood and tension wood
1. Compression wood:
1. It is the reaction wood of conifers which develops on the lower side of leaning trunk or branch
2. It is formed by the increases cambial activity on the lower side of the branch
3. It is 15-40% heavier than the normal wood and is rich in lignin
4. Formed in conifers like Pinus

2. Tension wood:
1. It is the reaction wood of dicots which develops on the upper side of leaning trunk or branch
2. It is formed by the increases cambial activity on the upper side of the branch
3. It is rich in cellulose and gelatinous fibres
4. Formed in dicots like Mango tree, Acacia etc
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Difference between Sense and Antisense strands of DNA

Sense strand vs antisense strand of DNA
A DNA molecule has a double stranded structure. It consists of two strands. Based on the strand that serves as template for mRNA formation or transcription, one strand is called the sense strand and the other is called the antisense strand.
Difference between sense strand and antisense strand of DNA

Sense strand
1. This strand is also called as coding strand, plus strand or non-template strand.
2. Coding strand is same as mRNA except that thymine in DNA is replaced by Uracil in RNA.
3. The coding strand contains codons.
8
Antisense strand
1. This strand is also called as non-coding strand, minus strand or template strand.
2. This strand acts as template for the synthesis of mRNA. Therefore antisense strand is complementary to the sense strand and mRNA (U in RNA in place of T).
3. The non-coding strand contains anti-codons.
Sense strand vs antisense strand of DNA
A DNA molecule has a double stranded structure. It consists of two strands. Based on the strand that serves as template for mRNA formation or transcription, one strand is called the sense strand and the other is called the antisense strand.
Difference between sense strand and antisense strand of DNA

Sense strand
1. This strand is also called as coding strand, plus strand or non-template strand.
2. Coding strand is same as mRNA except that thymine in DNA is replaced by Uracil in RNA.
3. The coding strand contains codons.
8
Antisense strand
1. This strand is also called as non-coding strand, minus strand or template strand.
2. This strand acts as template for the synthesis of mRNA. Therefore antisense strand is complementary to the sense strand and mRNA (U in RNA in place of T).
3. The non-coding strand contains anti-codons.
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Difference between Pili and Fimbriae

Pili and fimbriae are cell surface appendages present in bacteria other than flagella. These structures are not for locomotion.
Pili and fimbriae are surface appendages for attachment.
Pili and fimbriae Pili vs Fimbriae
Pili
Fimbriae
Long, thicker, tubular structures made up of protein pilin Thin and shorter than the pili
Pili are found only in Gram negative bacteria Fimbriae are found both in Gram negative and Gram positive bacteria
The number of pili are less (3-5 per cell) The number of fimbriae is 300-400 per cell
Formation of pili is governed by plasmid genes Formation of fimbriae is governed by bacterial genes in the nucleoid region
Pili involved in cell to cell attachment during bacterial conjugation. Therefore called as sex-pili Fimbriae is involved in cell to surface attachment of bacteria
Pili and fimbriae are cell surface appendages present in bacteria other than flagella. These structures are not for locomotion.
Pili and fimbriae are surface appendages for attachment.
Pili and fimbriae Pili vs Fimbriae
Pili
Fimbriae
Long, thicker, tubular structures made up of protein pilin Thin and shorter than the pili
Pili are found only in Gram negative bacteria Fimbriae are found both in Gram negative and Gram positive bacteria
The number of pili are less (3-5 per cell) The number of fimbriae is 300-400 per cell
Formation of pili is governed by plasmid genes Formation of fimbriae is governed by bacterial genes in the nucleoid region
Pili involved in cell to cell attachment during bacterial conjugation. Therefore called as sex-pili Fimbriae is involved in cell to surface attachment of bacteria
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Difference between Archaebacterial and Eubacterial flagella

Flagella are organs for movement in bacteria. Electron microscopic studies revealed that flagella consist of three components: a long filament made up of protein flagellin, a hook that connects the filament to the basal body and basal body embedded in the cell wall and plasma membrane from where the flagellum arises.
Flagella, pili and fimbriae

 Archaebacterial flagella vs Eubacterial flagella
1. Eubacterial flagella is thicker than archae bacterial flagella.
2. Eubacterial flagella is powered by flow of H+ ions.
    Archaebacterial flagella is ATP driven.
3. Eubacteria possess many flagellar filaments that rotates independently.
    Archae flagella are often bundled composed of many filaments that rotate as a single unit.
4. During growth of flagella, flagellin subunits are added at the tip in Eubacterial flagella where as in archeal flagella, flagellin subunits are added at the base.
Flagella are organs for movement in bacteria. Electron microscopic studies revealed that flagella consist of three components: a long filament made up of protein flagellin, a hook that connects the filament to the basal body and basal body embedded in the cell wall and plasma membrane from where the flagellum arises.
Flagella, pili and fimbriae

 Archaebacterial flagella vs Eubacterial flagella
1. Eubacterial flagella is thicker than archae bacterial flagella.
2. Eubacterial flagella is powered by flow of H+ ions.
    Archaebacterial flagella is ATP driven.
3. Eubacteria possess many flagellar filaments that rotates independently.
    Archae flagella are often bundled composed of many filaments that rotate as a single unit.
4. During growth of flagella, flagellin subunits are added at the tip in Eubacterial flagella where as in archeal flagella, flagellin subunits are added at the base.
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Difference between Stomata and Hydathodes (Water stomata)

Stomata are small apertures in the epidermal surface of a plant leaf, stem or flower through which gaseous exchange and water transpiration occur. Stomata are minute apertures in the epidermis of aerial parts of the plants bounded by two kidney shaped guard cells. Stomata are absent in roots.
stomata structure
It may occur three different positions in relation to epidermal cells:
 i) They may be at the same level as the adjoining epidermal cells as in most mesophytic plants. 
ii) In xerophytic plants, the stomata are sunken as they are located in a cup shaped depression.            iii) Sometimes the stomata are slightly raised above the surface of epidermis.  
Hydathodes are specialized pores along the margins and apex of the leaf through which the secretion of water (guttation) takes place. Hydathodes or water stomata consists of vein endings, epithem, chamber and pores. Pore is surrounded by guard cells but it remains open permanently.
hydathodes
Stomata vs Hydathodes (Water Stomata)
Stomata
1.  Stomata present only on the lower epidermis of dorsiventral leaf and on both epidermis of isobilateral leaf. (In the case of lotus stomata present on the upper epidermis.)
2. Guard cells always present and due to their flaccidity the stomatal pore may be closed.
3. Epithem does not present.
4. Only water comes out in the form of vapour through the stomata. No mineral salts liberated with water.
Hydathodes (Water stomata)
1. Water stomata present near the margin of leaf, like tomato
2. Guard cells always absent. The pore always remains open, and never closed.
3. Thin walled cells with intercellular spaces called epithem is present.
4. Water along with mineral (inorganic) salts are liberated thorough the pores in the form of liquid droplets.
Stomata are small apertures in the epidermal surface of a plant leaf, stem or flower through which gaseous exchange and water transpiration occur. Stomata are minute apertures in the epidermis of aerial parts of the plants bounded by two kidney shaped guard cells. Stomata are absent in roots.
stomata structure
It may occur three different positions in relation to epidermal cells:
 i) They may be at the same level as the adjoining epidermal cells as in most mesophytic plants. 
ii) In xerophytic plants, the stomata are sunken as they are located in a cup shaped depression.            iii) Sometimes the stomata are slightly raised above the surface of epidermis.  
Hydathodes are specialized pores along the margins and apex of the leaf through which the secretion of water (guttation) takes place. Hydathodes or water stomata consists of vein endings, epithem, chamber and pores. Pore is surrounded by guard cells but it remains open permanently.
hydathodes
Stomata vs Hydathodes (Water Stomata)
Stomata
1.  Stomata present only on the lower epidermis of dorsiventral leaf and on both epidermis of isobilateral leaf. (In the case of lotus stomata present on the upper epidermis.)
2. Guard cells always present and due to their flaccidity the stomatal pore may be closed.
3. Epithem does not present.
4. Only water comes out in the form of vapour through the stomata. No mineral salts liberated with water.
Hydathodes (Water stomata)
1. Water stomata present near the margin of leaf, like tomato
2. Guard cells always absent. The pore always remains open, and never closed.
3. Thin walled cells with intercellular spaces called epithem is present.
4. Water along with mineral (inorganic) salts are liberated thorough the pores in the form of liquid droplets.
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Difference between Angiosperms and Pteridophytes

Pteridophytes p(Gk. Pteron=feather; phyta=plants) are called as seedless vascular cryptogams as they represent the first group of land plants with vasculature, xylem and phloem. Plant body is sporophytic differentiated into true roots, stem and leaves. Pteridophytes are commonly called as the “botanical snakes” as they evolved after bryophytes (the amphibians of the plant kingdom).
Example: Pteris, Adiantum

Angiosperms (Gk. Angios=closed; spermae=seeds)
Angiosperms are flowering, seed bearing vascular plants that form the largest and the most evolved group of plant kingdom. They are true flowering plants where the seeds are completely enclosed inside a fruit wall. The ovules are protected inside the ovary which later develops into fruit.
Example: coconut, mango, rose
Difference between angiosperms and pteridophytes
1. Angiosperms are adapted to wide variety of environments (may be mesophytes, hydrophytes, xerophytes, epiphytes etc).
    Pteridophytes are mostly terrestrial moisture or shade loving plants.

2. Flowers, seeds and fruits are present. Therefore angiosperms are seed bearing plants.
    Flowers, seeds and fruits are absent. Therefore pteridophytes are spore bearing plants.

3. Angiosperms vary greatly in size and shape; may be herb, shrub or tree.
    Pteridophytes are generally herbaceous.

4. Xylem consists of well developed vessels and tracheids in angiosperms.
    Xylem lacks true vessels in Pteridophytes.

5. In phloem, companion cells and sieve tubes are present in angiosperms.
  In phloem, sieve cells are present, companion cells and sieve tubes are absent in pteridophytes.

6. In angiosperms, secondary growth is present except monocots.
    Secondary growth is absent in pteridophytes.

7. Angiosperms are heterosporous forming male and female spores which is critical for seed habit.
 Pteridophytes are mostly homosporous. Some pteridophytes like Selaginella is heterosporous but there is no seed formation.

8. In angiosperms, stamens and carpels are the male and female reproductive structures which are organized to form the flower.
    In pteridophytes, antheridium and archegonium are the male and the female sex organs.

9. In angiosperms, water is not essential for fertilization as pollination is siphonogamous (via pollen     tube) and gametes are without flagella.
    In pteridophytes, water is essential for fertilization and male gametes are ciliated.

10. In angiosperms, megasporangium is usually large.
      In pteridophytes, megasporangium is usually small.

11. In angiosperms, megasporangium is covered by one or more integuments that offers protection.
      In pteridophytes, integuments are absent.

12. In angiosperms, usually a single megaspore is functional in the entire megasporangium (ovule) and is retained within the magasporangium.
      In pteridophytes, many megaspores are functional and generally not retained in the                             megasporangium.

13. Tapetum is absent and endosperm is the nutritive tissue for the developing embryo in angiosperms.
      Tapetum is present, but endosperm is absent in pteridophytes.
Pteridophytes p(Gk. Pteron=feather; phyta=plants) are called as seedless vascular cryptogams as they represent the first group of land plants with vasculature, xylem and phloem. Plant body is sporophytic differentiated into true roots, stem and leaves. Pteridophytes are commonly called as the “botanical snakes” as they evolved after bryophytes (the amphibians of the plant kingdom).
Example: Pteris, Adiantum

Angiosperms (Gk. Angios=closed; spermae=seeds)
Angiosperms are flowering, seed bearing vascular plants that form the largest and the most evolved group of plant kingdom. They are true flowering plants where the seeds are completely enclosed inside a fruit wall. The ovules are protected inside the ovary which later develops into fruit.
Example: coconut, mango, rose
Difference between angiosperms and pteridophytes
1. Angiosperms are adapted to wide variety of environments (may be mesophytes, hydrophytes, xerophytes, epiphytes etc).
    Pteridophytes are mostly terrestrial moisture or shade loving plants.

2. Flowers, seeds and fruits are present. Therefore angiosperms are seed bearing plants.
    Flowers, seeds and fruits are absent. Therefore pteridophytes are spore bearing plants.

3. Angiosperms vary greatly in size and shape; may be herb, shrub or tree.
    Pteridophytes are generally herbaceous.

4. Xylem consists of well developed vessels and tracheids in angiosperms.
    Xylem lacks true vessels in Pteridophytes.

5. In phloem, companion cells and sieve tubes are present in angiosperms.
  In phloem, sieve cells are present, companion cells and sieve tubes are absent in pteridophytes.

6. In angiosperms, secondary growth is present except monocots.
    Secondary growth is absent in pteridophytes.

7. Angiosperms are heterosporous forming male and female spores which is critical for seed habit.
 Pteridophytes are mostly homosporous. Some pteridophytes like Selaginella is heterosporous but there is no seed formation.

8. In angiosperms, stamens and carpels are the male and female reproductive structures which are organized to form the flower.
    In pteridophytes, antheridium and archegonium are the male and the female sex organs.

9. In angiosperms, water is not essential for fertilization as pollination is siphonogamous (via pollen     tube) and gametes are without flagella.
    In pteridophytes, water is essential for fertilization and male gametes are ciliated.

10. In angiosperms, megasporangium is usually large.
      In pteridophytes, megasporangium is usually small.

11. In angiosperms, megasporangium is covered by one or more integuments that offers protection.
      In pteridophytes, integuments are absent.

12. In angiosperms, usually a single megaspore is functional in the entire megasporangium (ovule) and is retained within the magasporangium.
      In pteridophytes, many megaspores are functional and generally not retained in the                             megasporangium.

13. Tapetum is absent and endosperm is the nutritive tissue for the developing embryo in angiosperms.
      Tapetum is present, but endosperm is absent in pteridophytes.
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Difference between Viroids and Prions

Viroids are small, naked infectious RNA molecules. The term viroid was coined by T.O. Diener (1971) to describe the causal agent of the potato spindle tuber disease.

Prions are infectious protein particles causing neurological degenerative diseases in humans and animals. Stanley B. Prusiner discovered prions.
Viroids vs Prions 
viroids vs Prions
          Viroids:
1. It is an infectious RNA particle
2. Viroid is formed of only small single stranded circular RNA
3. A protein coat is absent. 
4. Viroids are inactivated by ribonuclease digestion but resistant to proteinase K and trypsin digestion
5. Viroid has a smaller size than viruses
6. Viroid infects only higher plants (Exception: hepatitis D virus in humans is similar to viroid)
Common plant diseases include Potato Spindle tuber disease, Chrysanthemum stunt disease. 
Prions: 
1. It is an infectious protein particle 
2. It is formed of only proteins 
3. RNA or DNA is absent 
4. Prions are inactivated by proteinase K and trypsin digestion but resistant to ribonuclease treatment 
5. Mostly, smaller than viroid 
6. Prions infects animals causing neurological degenerative diseases 
‘Mad cow disease’ (Bovine spongiform encephalopathy) in cow and Scrapie disease in sheep and goat. 
Creutzfeldt-Jakob Disease (CJD), Kuru and Gerstmann-Strausler-Sheinker syndrome in humans.
Viroids are small, naked infectious RNA molecules. The term viroid was coined by T.O. Diener (1971) to describe the causal agent of the potato spindle tuber disease.

Prions are infectious protein particles causing neurological degenerative diseases in humans and animals. Stanley B. Prusiner discovered prions.
Viroids vs Prions 
viroids vs Prions
          Viroids:
1. It is an infectious RNA particle
2. Viroid is formed of only small single stranded circular RNA
3. A protein coat is absent. 
4. Viroids are inactivated by ribonuclease digestion but resistant to proteinase K and trypsin digestion
5. Viroid has a smaller size than viruses
6. Viroid infects only higher plants (Exception: hepatitis D virus in humans is similar to viroid)
Common plant diseases include Potato Spindle tuber disease, Chrysanthemum stunt disease. 
Prions: 
1. It is an infectious protein particle 
2. It is formed of only proteins 
3. RNA or DNA is absent 
4. Prions are inactivated by proteinase K and trypsin digestion but resistant to ribonuclease treatment 
5. Mostly, smaller than viroid 
6. Prions infects animals causing neurological degenerative diseases 
‘Mad cow disease’ (Bovine spongiform encephalopathy) in cow and Scrapie disease in sheep and goat. 
Creutzfeldt-Jakob Disease (CJD), Kuru and Gerstmann-Strausler-Sheinker syndrome in humans.
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Difference between Mesophyll Chloroplast and Bundle Sheath Chloroplast

Photosynthesis is the anabolic reaction carried out by green plants responsible for life on this planet. It is the process by which suns light energy is converted to chemical energy which is the source of energy for all other living organisms.

Photosynthesis involves 2 reactions: Light reaction and Dark reaction
  • Light reaction: takes place in the grana of the chloroplast where light energy from the sun is converted to chemical energy in the form of ATP and NADPH
  • Dark reaction: takes place in the stroma of the chloroplast. The ATP and NADPH produced in the light reaction are used to fix CO2 to carbohydrates.
Certain plants such as sugarcane, sorghum, Amaranthus etc possess an alternate pathway of CO2 fixation in addition to C3 cycle. The first stable compound produced in this pathway is a 4-carbon compound, oxaloacetic acid, hence called as C4 cycle. In C4 cycle, chloroplast in both mesophyll and bundle sheath cells are involved in CO2 fixation. In C4 plants, initial carbon fixation takes place in the mesophyll cells and Calvin Benson cycle or C3 cycle occurs in the bundle sheath cells. This alteration helps C4 plants to prevent photorespiration and also providing optimum condition for the enzyme RuBP for CO2 fixation.
Mesophyll chloroplast vs Bundle sheath chloroplast in C4 Plants
Mesophyll chloroplast
1. Large well developed numerous grana are present.
2. The enzyme Ribulose bi phosphate carboxylase (RuBP carboxylase) is absent. Therefore no CO2 fixation or C3 cycle occurs. In C3 plants, RuBP carboxylase is abundantly present in mesophyll chloroplast where CO2 fixation occurs
3. The activity of photosystem II is high making plenty of ATP, NADPH2 and O2
4.  Starch grains are absent in mesophyll cells
5. The key enzymes of starch synthesis are absent in mesophyll cells.

Mesophyll Chloroplast and Bundle Sheath Chloroplast - Kranz anatomy

Bundle sheath chloroplast
1. Grana few or absent, if present very small and poorly developed.
2.High concentration of RuBP carboxylase. Therefore CO2 fixation or C3 cycle occurs.
3. Low activity of photosystem II , hence few ATP, NADPH2 and O2 generated
4. Abundant large starch grains are present in bundle sheath chloroplast
5. The key enzymes of starch synthesis (ADP-glucose pyrophosphorylase, starch synthase, and branching enzyme) are located primarily in the bundle sheath cells

Reference: Roles of the bundle sheath cells in leaves of C3plants Richard C. Leegood* J. Exp. Bot. (2008) 59 (7): 1663-1673.
Photosynthesis is the anabolic reaction carried out by green plants responsible for life on this planet. It is the process by which suns light energy is converted to chemical energy which is the source of energy for all other living organisms.

Photosynthesis involves 2 reactions: Light reaction and Dark reaction
  • Light reaction: takes place in the grana of the chloroplast where light energy from the sun is converted to chemical energy in the form of ATP and NADPH
  • Dark reaction: takes place in the stroma of the chloroplast. The ATP and NADPH produced in the light reaction are used to fix CO2 to carbohydrates.
Certain plants such as sugarcane, sorghum, Amaranthus etc possess an alternate pathway of CO2 fixation in addition to C3 cycle. The first stable compound produced in this pathway is a 4-carbon compound, oxaloacetic acid, hence called as C4 cycle. In C4 cycle, chloroplast in both mesophyll and bundle sheath cells are involved in CO2 fixation. In C4 plants, initial carbon fixation takes place in the mesophyll cells and Calvin Benson cycle or C3 cycle occurs in the bundle sheath cells. This alteration helps C4 plants to prevent photorespiration and also providing optimum condition for the enzyme RuBP for CO2 fixation.
Mesophyll chloroplast vs Bundle sheath chloroplast in C4 Plants
Mesophyll chloroplast
1. Large well developed numerous grana are present.
2. The enzyme Ribulose bi phosphate carboxylase (RuBP carboxylase) is absent. Therefore no CO2 fixation or C3 cycle occurs. In C3 plants, RuBP carboxylase is abundantly present in mesophyll chloroplast where CO2 fixation occurs
3. The activity of photosystem II is high making plenty of ATP, NADPH2 and O2
4.  Starch grains are absent in mesophyll cells
5. The key enzymes of starch synthesis are absent in mesophyll cells.

Mesophyll Chloroplast and Bundle Sheath Chloroplast - Kranz anatomy

Bundle sheath chloroplast
1. Grana few or absent, if present very small and poorly developed.
2.High concentration of RuBP carboxylase. Therefore CO2 fixation or C3 cycle occurs.
3. Low activity of photosystem II , hence few ATP, NADPH2 and O2 generated
4. Abundant large starch grains are present in bundle sheath chloroplast
5. The key enzymes of starch synthesis (ADP-glucose pyrophosphorylase, starch synthase, and branching enzyme) are located primarily in the bundle sheath cells

Reference: Roles of the bundle sheath cells in leaves of C3plants Richard C. Leegood* J. Exp. Bot. (2008) 59 (7): 1663-1673.
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Difference between sigma and pi bond

The process of mixing of atomic orbitals of nearly same energy to produce a set of entirely new orbitals of equivalent energy (hybrid orbitals) is known as hybridization. Atomic orbitals of almost the same energy belonging to the same atom or ion can take part in hybridization.. The number of hybrid orbitals formed is always equal to the number of atomic orbitals taking part in hybridization. The hybrid orbitals repel each other and tend to be farthest apart. Hybrid orbitals forms only sigma bonds) σ and pi bonds( π bonds )are formed by unhybridised orbitals.

Sigma bond: This type of covalent bond is formed by the axial or end to end overlapping of half filled atomic orbitals of the atoms participating in bonding. The electron cloud formed as a result of axial overlap is cylindrically symmetrical about inter nuclear axis.

Pi bond: This type of bond is formed by lateral or side wise overlap of the half filled atomic orbitals of the atoms participating in bonding. The pi bond consists of two charged clods above and below the plane of the atoms involved in bond formation.
Sigma bond vs Pi bond
Sigma bond (σ bonds)
1. The covalent bond formed by the overlap of atomic orbitals along the internuclear axis is called sigma bond.

2. The overlapping orbitals are oriented along the internuclear axis.

3. The bond is rotationally symmetrical around the internuclear axis

4. A as well as p orbitals can form this type of bonds.

5. It is stronger than a pi bond

Pi  bond (π bonds)
1. The covalent bond formed by the lateral overlap of two p orbitals which are mutually parallel but oriented perpendicular to the internuclear axis is called a pi bond.

2. The overlapping orbitals are oriented perpendicular to the inter nuclear axis.

3. The bond is not rotationally symmetrical around the internuclear axis.

4. Only p orbitals can form this bond.

5. It is weaker than a sigma bond.
The process of mixing of atomic orbitals of nearly same energy to produce a set of entirely new orbitals of equivalent energy (hybrid orbitals) is known as hybridization. Atomic orbitals of almost the same energy belonging to the same atom or ion can take part in hybridization.. The number of hybrid orbitals formed is always equal to the number of atomic orbitals taking part in hybridization. The hybrid orbitals repel each other and tend to be farthest apart. Hybrid orbitals forms only sigma bonds) σ and pi bonds( π bonds )are formed by unhybridised orbitals.

Sigma bond: This type of covalent bond is formed by the axial or end to end overlapping of half filled atomic orbitals of the atoms participating in bonding. The electron cloud formed as a result of axial overlap is cylindrically symmetrical about inter nuclear axis.

Pi bond: This type of bond is formed by lateral or side wise overlap of the half filled atomic orbitals of the atoms participating in bonding. The pi bond consists of two charged clods above and below the plane of the atoms involved in bond formation.
Sigma bond vs Pi bond
Sigma bond (σ bonds)
1. The covalent bond formed by the overlap of atomic orbitals along the internuclear axis is called sigma bond.

2. The overlapping orbitals are oriented along the internuclear axis.

3. The bond is rotationally symmetrical around the internuclear axis

4. A as well as p orbitals can form this type of bonds.

5. It is stronger than a pi bond

Pi  bond (π bonds)
1. The covalent bond formed by the lateral overlap of two p orbitals which are mutually parallel but oriented perpendicular to the internuclear axis is called a pi bond.

2. The overlapping orbitals are oriented perpendicular to the inter nuclear axis.

3. The bond is not rotationally symmetrical around the internuclear axis.

4. Only p orbitals can form this bond.

5. It is weaker than a sigma bond.
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Difference between Epigeal and Hypogeal Seed Germination

The term germination designates the overall processes beginning with the imbibition of water by dry seed and ending when a portion of the embryo penetrates the seed coat. This process include cell division, embryo enlargement and increase in metabolic activities.
There are two types of germination:   Epigeal and Hypogeal
Epigeal vs Hypogeal
Epigeal Germination: (epi (Gk) means above, geal (Gk): earth)

Example: Bean, Castor
1. In this type of germination, the seed /cotyledons emerge out of the soil or above the soil.
2. The cotyledons turn green (photosynthetic) and act as first leaves of the plant.
3. There is greater elongation of the hypocotyl.
4.The terminal part of hypocotyl is curved to protect the plumule from the friction of the soil.
5. Energy for growth primarily derived from cotyledon

Hypogeal Germination: (hypo (Gk) means below, geal (Gk): earth)
Hypogeal Seed Germination
Example : Pea, Maize, Coconut
1. In this type of germination, the seed/ cotyledons remain inside the soil or below the soil.
2. The cotyledons play no role in photosynthesis.
3. There is greater elongation of the epicotyl.
4. The terminal part of the epicotyl is curved to protect the plumule from friction.
5. Energy for growth primarily derived from endosperm
The term germination designates the overall processes beginning with the imbibition of water by dry seed and ending when a portion of the embryo penetrates the seed coat. This process include cell division, embryo enlargement and increase in metabolic activities.
There are two types of germination:   Epigeal and Hypogeal
Epigeal vs Hypogeal
Epigeal Germination: (epi (Gk) means above, geal (Gk): earth)

Example: Bean, Castor
1. In this type of germination, the seed /cotyledons emerge out of the soil or above the soil.
2. The cotyledons turn green (photosynthetic) and act as first leaves of the plant.
3. There is greater elongation of the hypocotyl.
4.The terminal part of hypocotyl is curved to protect the plumule from the friction of the soil.
5. Energy for growth primarily derived from cotyledon

Hypogeal Germination: (hypo (Gk) means below, geal (Gk): earth)
Hypogeal Seed Germination
Example : Pea, Maize, Coconut
1. In this type of germination, the seed/ cotyledons remain inside the soil or below the soil.
2. The cotyledons play no role in photosynthesis.
3. There is greater elongation of the epicotyl.
4. The terminal part of the epicotyl is curved to protect the plumule from friction.
5. Energy for growth primarily derived from endosperm
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Difference between Ribose and Ribulose

Carbohydrates are the most abundant class of biomolecules in nature. A carbohydrate is composed of carbon, hydrogen and oxygen with a general formula (CH2O)n where ‘n’ is 3 or more (n= no. of C atom).Chemically carbohydrates are poly hydroxyl aldehydes or ketones and their derivatives or as substances that yield one of these compounds on hydrolysis.
Both ribose and ribulose are monosaccharides. Monosaccharide’s or simple sugars consists of a carbon chain with number of hydroxyl groups plus either an aldehyde (-CHO) or a ketone group(=C=O).
Similarities between Ribose and Ribulose
1. Both are monosaccharides or simple sugars
2. The chemical formula or composition is the same C5H10O5. They are structural isomers.
3. Both are pentoses (5 carbon containing sugars)
4. Both this compounds are biologically important
Ribose and Ribulose
Differences between Ribose and Ribulose  (Refer figure and see the Carbon numbering in red)
1. Ribose is an aldose sugar (with an aldehyde group –CHO) or ribose is an aldopentose
    Ribulose is a ketose sugar (with a keto group (=C=O) or ribulose is ketopentose.
2. The chemical formula of ribose and ribulose is C5H10O5. But are structurally different. They are structural isomers.   
  Structural isomers are compounds with same chemical composition but differ in structure
3. In ribose, the double bond is on the first carbon.
    In ribulose, the second carbon has the double bond
4. Ribose sugar forms the backbone of ribonucleic acid (RNA) 
    Ribulose biphosphate is the initial CO2 acceptor in dark reaction or Calvin cycle of photosynthesis.
Carbohydrates are the most abundant class of biomolecules in nature. A carbohydrate is composed of carbon, hydrogen and oxygen with a general formula (CH2O)n where ‘n’ is 3 or more (n= no. of C atom).Chemically carbohydrates are poly hydroxyl aldehydes or ketones and their derivatives or as substances that yield one of these compounds on hydrolysis.
Both ribose and ribulose are monosaccharides. Monosaccharide’s or simple sugars consists of a carbon chain with number of hydroxyl groups plus either an aldehyde (-CHO) or a ketone group(=C=O).
Similarities between Ribose and Ribulose
1. Both are monosaccharides or simple sugars
2. The chemical formula or composition is the same C5H10O5. They are structural isomers.
3. Both are pentoses (5 carbon containing sugars)
4. Both this compounds are biologically important
Ribose and Ribulose
Differences between Ribose and Ribulose  (Refer figure and see the Carbon numbering in red)
1. Ribose is an aldose sugar (with an aldehyde group –CHO) or ribose is an aldopentose
    Ribulose is a ketose sugar (with a keto group (=C=O) or ribulose is ketopentose.
2. The chemical formula of ribose and ribulose is C5H10O5. But are structurally different. They are structural isomers.   
  Structural isomers are compounds with same chemical composition but differ in structure
3. In ribose, the double bond is on the first carbon.
    In ribulose, the second carbon has the double bond
4. Ribose sugar forms the backbone of ribonucleic acid (RNA) 
    Ribulose biphosphate is the initial CO2 acceptor in dark reaction or Calvin cycle of photosynthesis.
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Difference between Sieve cells and Sieve tubes

Both sieve cells and sieve tubes are constituents of phloem involved in conduction of food
Sieve cells and Sieve tubes
Sieve cells vs Sieve tubes
Sieve cells
1. Sieve cells are elongated cells with tapering end walls
2. Sieve cells have no companion cells associated with it
3. In sieve cells, the sieve areas do not form sieve plates
4. In sieve cells, the sieve areas are not well differentiated
5. Found in pteridophytes and gymnosperms
Sieve tubes
1. Sieve tubes consist of vertical cells placed one above the other forming long tubes connected at the end walls by sieve pores
2. Sieve tubes have companion cells associated with it
3. In sieve tubes, the sieve areas are confined to sieve plates
4. In sieve tubes, the sieve areas are well differentiated
5. Found in angiosperms
Both sieve cells and sieve tubes are constituents of phloem involved in conduction of food
Sieve cells and Sieve tubes
Sieve cells vs Sieve tubes
Sieve cells
1. Sieve cells are elongated cells with tapering end walls
2. Sieve cells have no companion cells associated with it
3. In sieve cells, the sieve areas do not form sieve plates
4. In sieve cells, the sieve areas are not well differentiated
5. Found in pteridophytes and gymnosperms
Sieve tubes
1. Sieve tubes consist of vertical cells placed one above the other forming long tubes connected at the end walls by sieve pores
2. Sieve tubes have companion cells associated with it
3. In sieve tubes, the sieve areas are confined to sieve plates
4. In sieve tubes, the sieve areas are well differentiated
5. Found in angiosperms
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Difference between Sap wood and Heart wood

Sap wood is the functional, conducting part of the wood whereas heart wood is the non functional, non conducting part of the wood.
Sap wood vs Heart wood
Sap wood vs Heart wood
Sap wood
1. The outer region of the old trees forms the sap wood
2. It is also called as alburnum
3. it is soft and not durable
4. It is light coloured and formed of living cells
5. Vessels are not blocked by tyloses
6. The function of this region is conduction of water and nutrients and also storage of food
Heartwood
1. The central region of the old trees forms the sap wood
2. It is also called as duramen
3. it is hard and durable
4. It is dark coloured due to the deposition of various substances
5. Vessels are blocked by tyloses with various deposits
6. The function of this region is mechanical support
Sap wood is the functional, conducting part of the wood whereas heart wood is the non functional, non conducting part of the wood.
Sap wood vs Heart wood
Sap wood vs Heart wood
Sap wood
1. The outer region of the old trees forms the sap wood
2. It is also called as alburnum
3. it is soft and not durable
4. It is light coloured and formed of living cells
5. Vessels are not blocked by tyloses
6. The function of this region is conduction of water and nutrients and also storage of food
Heartwood
1. The central region of the old trees forms the sap wood
2. It is also called as duramen
3. it is hard and durable
4. It is dark coloured due to the deposition of various substances
5. Vessels are blocked by tyloses with various deposits
6. The function of this region is mechanical support
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Difference between Enveloped and Non enveloped Virus

Viruses are infectious intracellular obligate parasites consisting of nucleic acid (RNA or DNA) enclosed in a protein coat called capsid
In some cases, a membranous envelope may be present outer to the capsid
Viruses are classified based on the presence or absence of this envelope around the protein coat
1. Enveloped viruses eg: Herpes simplex, Chickenpox virus, Influenza virus etc
2. Non-enveloped viruses eg: Adeno virus, parvovirus etc
Characteristics of viral envelope
  • Made of lipid and proteins rarely glycoprotein
  • May be modified host plasma membrane or internal membranes
  • Projections from the envelope are known as spikes or peplomers
Function: attachment of the virus to the host cell.
  • HIV virus uses its spikes for this purpose.
Non enveloped viruses:
Non enveloped viruses - Adeno virus
1. The outermost covering is the capsid made up of proteins
2. Non enveloped viruses are more virulent and causes host cell lysis
3. These viruses are resistant to heat, acids, and drying
4. It can survive inside gastrointestinal tract
5. It can retain its infectivity even after drying
6. It will induce antibody production in the host
7. Mode of transmission is through fecal or oral matter, formites and dust
Enveloped viruses
Enveloped viruses - Influenza virus
1. The outermost envelope is made up of phospholipids, proteins or glycoprotein which surround the capsid
2. Enveloped viruses are less virulent often released by budding and rarely cause host cell lysis
3. Are sensitive to heat, acids, and drying
4. Generally it cannot survive inside gastrointestinal tract
5. It lose its infectivity on drying
6. It will induce both cell mediated and antibody mediated immune response in the host
7. Mode of transmission is through blood or organ transplants or through secretions
Viruses are infectious intracellular obligate parasites consisting of nucleic acid (RNA or DNA) enclosed in a protein coat called capsid
In some cases, a membranous envelope may be present outer to the capsid
Viruses are classified based on the presence or absence of this envelope around the protein coat
1. Enveloped viruses eg: Herpes simplex, Chickenpox virus, Influenza virus etc
2. Non-enveloped viruses eg: Adeno virus, parvovirus etc
Characteristics of viral envelope
  • Made of lipid and proteins rarely glycoprotein
  • May be modified host plasma membrane or internal membranes
  • Projections from the envelope are known as spikes or peplomers
Function: attachment of the virus to the host cell.
  • HIV virus uses its spikes for this purpose.
Non enveloped viruses:
Non enveloped viruses - Adeno virus
1. The outermost covering is the capsid made up of proteins
2. Non enveloped viruses are more virulent and causes host cell lysis
3. These viruses are resistant to heat, acids, and drying
4. It can survive inside gastrointestinal tract
5. It can retain its infectivity even after drying
6. It will induce antibody production in the host
7. Mode of transmission is through fecal or oral matter, formites and dust
Enveloped viruses
Enveloped viruses - Influenza virus
1. The outermost envelope is made up of phospholipids, proteins or glycoprotein which surround the capsid
2. Enveloped viruses are less virulent often released by budding and rarely cause host cell lysis
3. Are sensitive to heat, acids, and drying
4. Generally it cannot survive inside gastrointestinal tract
5. It lose its infectivity on drying
6. It will induce both cell mediated and antibody mediated immune response in the host
7. Mode of transmission is through blood or organ transplants or through secretions
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Difference between Oncogene and Tumor Suppressor Genes

Two major classes of genes contribute to causing cancer i.e., Oncogenes and Tumour suppressor genes. Oncogenes must be activated to cause cancer. Tumour suppressor genes, which normally hold mitosis in check, must be inactivated or removed to eliminate control of the cell cycle and initiate cancer.
Oncogenes are genes that normally activate during cell division in specific situations. Oncogene activation at wrong place or time during cell division may lead to cancer. Oncogenes are not alien to the cell, they are normal, essential genes that have undergone a mutation. In its normal non mutated state, it is called proto-oncogene, a gene that can be transformed into an oncogene.
 examples oncogene
Activation of proto-oncogene to oncogene is achieved by different mechanisms like promoter and enhancer insertion, chromosomal translocation, gene amplification and point mutation.
Oncogene vs tumour suppressor genes
Tumor suppressor genes as the term suggested it prevents or suppresses tumor formation by regulating cell division. Tumor suppressor genes are now recognized as key players in the genesis of cancer. Malfunctioning of tumor suppressor genes may lead to uncontrolled cell division. Researchers have identified about a half dozen tumor suppressor genes. Important tumor suppressor genes include RB I and p53, both of which are nuclear phosphoproteins and probably affect the transcription of genes involved in regulating events in the cell cycle.
Oncogene vs Tumor Suppressor Genes
Oncogene
1. Mutation in one of the two alleles is sufficient for activity as an oncogene and often act dominant to wild type.
2. Mutation often occurs in somatic tissues therefore not inherited
3. Conversion of protooncogene to oncogene is often a “gain of function” of protein that signals uncontrolled cell division.
4. Some tissue preference.
Tumor Suppressor Genes
1. Tumor suppressor gene malfunctioning is caused by mutations in both alleles or a mutation in one followed by a loss of or reduction to homozygosity in the second.
2. Mutation may occur   in germ cell (can be inherited) or somatic cells.
3. ‘Loss of function’ mutation is the reason for tumor suppressor gene malfunctioning.
4. Strong tissue preference in the case of mant tumor suppressor genes (Example: effect of RB II gene in retina)

Two major classes of genes contribute to causing cancer i.e., Oncogenes and Tumour suppressor genes. Oncogenes must be activated to cause cancer. Tumour suppressor genes, which normally hold mitosis in check, must be inactivated or removed to eliminate control of the cell cycle and initiate cancer.
Oncogenes are genes that normally activate during cell division in specific situations. Oncogene activation at wrong place or time during cell division may lead to cancer. Oncogenes are not alien to the cell, they are normal, essential genes that have undergone a mutation. In its normal non mutated state, it is called proto-oncogene, a gene that can be transformed into an oncogene.
 examples oncogene
Activation of proto-oncogene to oncogene is achieved by different mechanisms like promoter and enhancer insertion, chromosomal translocation, gene amplification and point mutation.
Oncogene vs tumour suppressor genes
Tumor suppressor genes as the term suggested it prevents or suppresses tumor formation by regulating cell division. Tumor suppressor genes are now recognized as key players in the genesis of cancer. Malfunctioning of tumor suppressor genes may lead to uncontrolled cell division. Researchers have identified about a half dozen tumor suppressor genes. Important tumor suppressor genes include RB I and p53, both of which are nuclear phosphoproteins and probably affect the transcription of genes involved in regulating events in the cell cycle.
Oncogene vs Tumor Suppressor Genes
Oncogene
1. Mutation in one of the two alleles is sufficient for activity as an oncogene and often act dominant to wild type.
2. Mutation often occurs in somatic tissues therefore not inherited
3. Conversion of protooncogene to oncogene is often a “gain of function” of protein that signals uncontrolled cell division.
4. Some tissue preference.
Tumor Suppressor Genes
1. Tumor suppressor gene malfunctioning is caused by mutations in both alleles or a mutation in one followed by a loss of or reduction to homozygosity in the second.
2. Mutation may occur   in germ cell (can be inherited) or somatic cells.
3. ‘Loss of function’ mutation is the reason for tumor suppressor gene malfunctioning.
4. Strong tissue preference in the case of mant tumor suppressor genes (Example: effect of RB II gene in retina)

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Difference between Kharif crops and Rabi crops with examples

When plants of the same kind are grown and cultivated at one place on a a large scale is called as a crop. Crops are classified on the basis of the seasons: Kharif and Rabi crops.
Kharif crop vs Rabi crop
Kharif crops (Monsoon crops): The crops which are grown during the monsoon (rainy season) are called kharif crops.  Seeds of the se crops are sown in the beginning of the monsoon season. After maturation, these crops are harvested at the end of the monsoon season (Oct-Nov).
Example: Paddy, maize, millet and cotton crops
Rabi crops (Winter crops): Crops which are grown during the winter season(October-March) are called Rabi crops. Seeds of these crops are sown in the beginning of the winter season. After maturation of crops, they are harvested at the end of the winter season (April- May).
Example: Wheat, Gram and Mustard.
When plants of the same kind are grown and cultivated at one place on a a large scale is called as a crop. Crops are classified on the basis of the seasons: Kharif and Rabi crops.
Kharif crop vs Rabi crop
Kharif crops (Monsoon crops): The crops which are grown during the monsoon (rainy season) are called kharif crops.  Seeds of the se crops are sown in the beginning of the monsoon season. After maturation, these crops are harvested at the end of the monsoon season (Oct-Nov).
Example: Paddy, maize, millet and cotton crops
Rabi crops (Winter crops): Crops which are grown during the winter season(October-March) are called Rabi crops. Seeds of these crops are sown in the beginning of the winter season. After maturation of crops, they are harvested at the end of the winter season (April- May).
Example: Wheat, Gram and Mustard.
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Difference between Thermoplastics and Thermosetting plastics

Plastics is easily mouldable, recycled, reused, coloured, melted, rolled into sheets or made into wires.
Thermoplastics: These are the plastics which get deformed easily on heating and can be bent easily.
Examples: PVC and Polythene are used for manufacturing combs, toys, car grills and various type of containers.
Thermoplastics vs Thermosetting Plastics
Thermosetting plastics: These are the plastics which when molded once, cannot be softed by heating.
Examples: Bakelite and Melamine. Bakelite is a poor conductor of heat and light. Bakelites are used for making electrical switches, handles of various utensils etc. Melamine is resistant to fire and can tolerate heat better than other plastics. Melamines are used for making floor tiles, kitchen wares and fabrics.
Plastics is easily mouldable, recycled, reused, coloured, melted, rolled into sheets or made into wires.
Thermoplastics: These are the plastics which get deformed easily on heating and can be bent easily.
Examples: PVC and Polythene are used for manufacturing combs, toys, car grills and various type of containers.
Thermoplastics vs Thermosetting Plastics
Thermosetting plastics: These are the plastics which when molded once, cannot be softed by heating.
Examples: Bakelite and Melamine. Bakelite is a poor conductor of heat and light. Bakelites are used for making electrical switches, handles of various utensils etc. Melamine is resistant to fire and can tolerate heat better than other plastics. Melamines are used for making floor tiles, kitchen wares and fabrics.
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Difference between Stars and Planets

Stars are the celestial bodies which can emit heat and light continuously. Every star is a huge mass of hot gases and emit big flames. Stars appear to twinkle at night which is a visual illusion because of the disturbances on the atmosphere. The sun being the closet star of the earth, the bright light of sun make other stars invisible during day time.   
The bodies which revolve around the sun in a certain orbit are called planets. There are following eight planets: Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus and Neptune.
Planet vs Star

Planets vs Stars
Planets
1. Planets do not twinkle in the sky.
2. They have no light.
3. They revolve around the sun.
4. Planets are small as compared to star.
Stars
1. Stars twinkle in the sky.
2. They have their own light.
3. They are fixed at a point.
4. They are very big in size.
Stars are the celestial bodies which can emit heat and light continuously. Every star is a huge mass of hot gases and emit big flames. Stars appear to twinkle at night which is a visual illusion because of the disturbances on the atmosphere. The sun being the closet star of the earth, the bright light of sun make other stars invisible during day time.   
The bodies which revolve around the sun in a certain orbit are called planets. There are following eight planets: Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus and Neptune.
Planet vs Star

Planets vs Stars
Planets
1. Planets do not twinkle in the sky.
2. They have no light.
3. They revolve around the sun.
4. Planets are small as compared to star.
Stars
1. Stars twinkle in the sky.
2. They have their own light.
3. They are fixed at a point.
4. They are very big in size.
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Difference Between the Secondary Growth in Dicot Stem and Dicot Root

The growth in thickness by the activity of secondary tissues is called secondary thickening. It involves stelar growth by the activity of vascular cambial ring and extra stelar growth by the activity  of cork cambium.
Dicot stem
secondary Growth in Dicotyledonous Stem
1. The cambial ring formed is circular in cross section from the beginning onwards.
2. The cambial ring is partially primary (fascicular cambium) and partially secondary (interfascicular cambium).
3. Periderm orginates from the cortical cells (extra stelar in origin).
4. In Dicot stem, for mechanical support xylem is with comparatively smaller vessels, greater fibers and less parenchyma.
5. More amount of cork is produced for protection.
6. Lenticels on periderm are very prominent.

Dicot root
DICOT ROOT SECODARY THICKENING
1. The cambial ring formed is wavy in the beginning and later becomes circular.
2. The cambial ring is completely secondary in origin.
3. Periderm originates from the pericycle (intra stelar in origin).
4. In Dicot root, xylem is with big thin walled vessels with few fibers and more parenchyma.
5. Less amount of cork is produced as root is underground.
6. Lenticels on periderm are not very prominent.
The growth in thickness by the activity of secondary tissues is called secondary thickening. It involves stelar growth by the activity of vascular cambial ring and extra stelar growth by the activity  of cork cambium.
Dicot stem
secondary Growth in Dicotyledonous Stem
1. The cambial ring formed is circular in cross section from the beginning onwards.
2. The cambial ring is partially primary (fascicular cambium) and partially secondary (interfascicular cambium).
3. Periderm orginates from the cortical cells (extra stelar in origin).
4. In Dicot stem, for mechanical support xylem is with comparatively smaller vessels, greater fibers and less parenchyma.
5. More amount of cork is produced for protection.
6. Lenticels on periderm are very prominent.

Dicot root
DICOT ROOT SECODARY THICKENING
1. The cambial ring formed is wavy in the beginning and later becomes circular.
2. The cambial ring is completely secondary in origin.
3. Periderm originates from the pericycle (intra stelar in origin).
4. In Dicot root, xylem is with big thin walled vessels with few fibers and more parenchyma.
5. Less amount of cork is produced as root is underground.
6. Lenticels on periderm are not very prominent.
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