how the expression of recessive allele appeares in the phenotype?

Question

anonymous · Answer

Lower Case . E.g. b in Bb 
Bb means B dominating recessive b

anonymous · Answer

B itself is allele and b itself is another allele , they are two different allele whereby B dominates b which is recessive. This is also known as a Heterozygous pair. If it is bb, then both alleles are recessive and form a homozygous recessive pair. http://en.wikipedia.org/wiki/File:Punnett_square_mendel_flowers.svg

shrutipande9 · Answer

expression of recessive allele in normal type occurs only when it is present in bb recessive homozygous condition. the expression of that allele depends on what it is coding for. for eg r codes for white flowers....

rina.r · Answer

The offspring would have to have be homozygous for the recessive allele. Like... rr. (r being the recessive allele and R being the dominant allele)

The parents would have to be:
Rr x Rr (there would be a 25% chance of having a child homozygous for the recessive allele, rr)
Rr x rr (there would be a 50% chance of having a child homozygous for the recessive allele, rr)
rr x rr (there would be a 100% chance of having a child homozygous for the recessive allele, rr)

Well, this is assuming that the recessive allele is being passed on autosomes. If it's a sex linked (X-linked) trait, it would have a higher probability of being passed on to males, since for sex chromosomes, males only get one X chromosome and one Y chromosome, while females get two X chromosomes.

So if a trait is X-linked, it would only take one X chromosome with the recessive allele for the male to display the recessive phenotype. Females, however, would need to have two X chromosomes with the recessive allele in order to display the recessive phenotype. If she just had one X chromosome with the recessive allele, however, she would just be a carrier for the phenotype (she would not display symptoms).

For example!
XY (normal - X = normal, not having the recessive allele)
RY (This guy would have the recessive phenotype since his X carries the recessive allele - is not normal (the R))
XX (normal female)
XR (carrier female - she has only one X with the recessive allele)
RR (female who is affected - she has two X's with the recessive allele)