Difference Between Monohybrid and Dihybrid

Mendel's earlier experiments in garden pea (Pisum sativum) were mono hybrid crosses. A cross involving contrasting expression of one trait is transferred to as monohybrid cross. For example, in order to learn inheritance of plant height, a tall pea plant was crossed with a dwarf one; all other traits were ignored.
Monohybrid cross
Inheritance of two pairs of alleles through a number of generations was studied by Mendel through dihybrid crosses. In one experiment Mendel crossed a round green’ with a wrinkled yellow. The F1 individuals, called dihybrid, were all round yellow. Two members of the F1 were crossed to raise the F2 . The result was 315 round yellow + 108 round green + 101 wrinkled yellow +  32 wrinkled green. This observed figures closely approximated a 9:3:3:1 ratio.
Dihybrid cross
Monohybrid vs Dihybrid
Monohybrid
Dihybrid
 It is a cross between two pure organisms in order to study the inheritance of a single pair of alleles.
 It is a cross between two pure organisms of a species in order to study the inheritance of two pairs of alleles belonging to two different characters.
 It produces  a phenotypic monohybrid ratio of 3:1 in F2 generation.
 It produces a phenotypic dihybrid ratio of 9:3:3:1 in F2 generation.
 It produces genotypic ratio of 1:2:1 in F2.
 It produces genotypic ratio of 1:2:1:2:4:2:1:2:1
 Test cross ratio - 1:1
 Test cross ratio -1:1:1:1


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11 comments:

harsh dev sharma said...

explain the topic more deeply...
plz.

Unknown said...

it makes no sense...
any other way of explaining it please??

Unknown said...

this website has helped me through exams, thankyou for the easy and short notes. good for revising on the go.

aniket singh said...

very good site :) but not explanation :( properly

Anonymous said...

Hey, if you guys explain some of the terminology you used here a little further visitors will be able to better understand what you are explaining :) explain as if you are teaching someone at a beginner level

Anonymous said...

it helps me, but I feel like I need a deeper meaning between these two crosses.

Matthew Johnson said...

Simplified for some ... The monohybrid F1 is bred from 2 true breeding (homozygotes) parental lines. This results in a more uniform line of offspring, breeding the next generation will show multiple phenotypes as they can grab traits (alelles) from recessive genes from grand-parents. Selective breeding more gens will bottleneck genetics limiting phenos until make new IBL (inbred line) that breeds true for selected traits, hybrids are also referred to as heterozygotes. However using parents that aren't true breeding (heterozygote) will result in a dihybrid, these usually have multiple phenotypes due to more random gene mixing. The dihybrids are also referred to as poly-hybrids, breeding further wil result in even more phenos (traits). Hope that helps a little for those wanting further explination.

smalleagle.com said...

Please explain more deeply and use simple terms. Thank you.

Anonymous said...

useful

Anonymous said...

OK i will try make it easier to understand (Matthew hit nail on head so will simply expand on and simplify his a little), first lets run through basic terms. Homozygotes are heirloom/landrace very inbred lines : Heterozygotes are any hybrid and will not be true breeding : allele is a certain characteristic (our eye colour is an allele) Phenotype is the outward expression (looks) and is made up of 50% genetics (genotype) and 50% growing environment. Breeding together 2 inbred (heirloom) cultivars will result in a monohybrid (should be fairly uniform with 3:1 ratio according to Mendels law of inheritance). How ever taking 2 different single crosses (another term for monohybrid) then hybridizing them (crossing with each other) will result in a double cross (laymens term for dihybrid) and again referring to Mendels law of inheritance will result in phenotype ratio of 9:3:3:1. Also Mendel is considered on of the grandfathers in plant breeding (Gregor Mendel) whom was an Augustinian monk who spent years experimenting with peas in the 19th centurary

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