Genotype and phenotype?

Question

I need help with this very much. The problem is:Red eyes [R] are dominant to Green eyes [r]. Find all of the possible phenotypes, and genotypes. How do I do this??

Answer 1

Genotypes. Genotypes are the possible combinations of alleles:

RR

Rr (which is also rR)

rr

(these are all possible combinations of two traits where each is either R or r)

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Phenotypes. Phenotypes are the possible manifestations of these in an animal:

red eyes

green eyes

(these are the only two possibilities in the offspring as you have presented it)

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From http://dictionary.reference.com/browse/g...

gen·o·type - the genetic makeup of an organism or group of organisms with reference to a single trait, set of traits, or an entire complex of traits.

From http://dictionary.reference.com/browse/p...

phe·no·type - the observable constitution of an organism; the appearance of an organism resulting from the interaction of the genotype and the environment.

Answer 2

First you must make crosses. Example:

Cross RR (homozygous dominant) with rr (homozygous recessive). The genotype (allelic combination) possible is just Rr (heterozygous dominant). Therefore the only possible phenotype are red-eyed offsprings.

Another example:

   Rr with Rr = RR,Rr and rr....both phenotypes are possible