Jenny has red hair and freckles. We know that non-red hair (R) is dominant to red hair (r), and that freckles (F) are dominant to plain skin (f). She tells you that her mom has brown hair and freckles, and that her dad has red hair and plain skin. Furthermore, she says that her maternal grandmother (her mom’s mom) had red hair and plain skin. What is Jenny’s genotype?

In this question, we’re talking about two traits, which means that we will represent their genotypes with four letters ( two letters for each trait, since one trait is present in two chromosomes -pair-, one from the mother, and one from the father, revise if you don't get it, or just ask me).

First, let’s make everything clear:

Capital letters are for dominant traits (if one dominant trait is present in the genotype, it will be shown as the phenotype of a person)

Small letters are for recessive traits (if both chromosomes have the recessive trait, it will be shown as the phenotype)

( one letter = one allele )

R : not-red hair r : red hair

F : freckles f : plain skin

Second, let's write down every possible genotype for each person:

Let's start with Jenny, she has a recessive trait (red hair) and a dominant trait (freckles). As I mentioned before, we will represent recessive traits in two small letters ( rr for Jenny's red hair ). And in the case of our dominant trait ( freckles), we MUST have at least one capital letter (for this trait: F ). That means we have two possible genotypes for freckles: either Ff or FF.

Now as easy as it sounds, we should write Jenny's possible genotypes like this:

Either rrFf or rrFF

Jenny's mother has brown hair and freckles (two dominant traits), again, as I mentioned before, dominant traits MUST be represented by at least one capital letter.

Possible genotypes for brown hair:

either RR or Rr

Possible genotypes for freckles:

either FF or Ff

Here, we have the phenotype of one parent of Jenny's mother's parents. Lucky for us, Jenny's grandmother has two recessive traits that can only be presented as rrff.

Why are we lucky? Because Jenny's mother must have inherited one allele of her grandmother, since both of Jenny's grandmother's alleles are the same, we know that Jenny's mother has one r allele and one f allele. We can write down Jenny's mother's genotype like this: RrFf.

Now I ask you to stop reading and try to figure out Jenny's father's genotype.

It is rrff, just like her grandmother.

Finally, let's make a Punnett square for Jenny's genotype:

mother: father:

RrFf x rrff

( I'm not gonna show you how to make a Punnett square because that's gonna be a tooooooo long explanation, watch this video: https://youtu.be/qIGXTJLrLf8 )

possible genotypes for Jenny and her siblings:

RrFf (phenotype: non-red hair & freckles)

or Rrff (phenotype: non-red h & plain skin)

or rrFf (phenotype: red h & freckles)

or rrff (phenotype: red h & plain face)

If Jenny has red hair and freckles, she MUST have a genotype of rrFf. If not, her mother is cheating XD (or a genetic mutation had happened).

I know I took too long explaining and answering but I hope I helped you,

keep it up!!

Histrionicus Histrionicus · Answer 2 · 2021-09-09T13:14:38+02:00

The correct genotype Jenny would be - rrFf .

The information we have in this question is:

non-red hair (R) is dominant to red hair (r),
freckles (F) are dominant to plain skin (f).
dad has red hair and plain skin
mom has brown hair and freckles,
Jenny has red hair and freckles
maternal grandmother had red hair and plain skin

Let find the genome of her maternal grandmother:

Her maternal grandmother had red hair skin which is a recessive trait and plain skin which is also a recessive trait that means she must have both recessive alleles for each trait as recessive allele express itself in the absence of dominant allele

The genotype of maternal grandmother: rrff

Let find the genome of the mother:

Mother has brown hair and freckles and brown hair is only present in heterozygous conditions if R allele is present with r allele however, Freckles can be in two conditions FF or Ff. The mother of jenny's mother has rrff then she must carry one f allele which concludes that Jenny mother has Ff.

The genotype of mother: RrFf

Let find the genome of her father:

Her father has red hair and plain skin and as we explained that both are recessive traits then the genotype of her father would be - rrff

Finally, the genotype of jenny can find out by the cross between the genotype of her parents:

(see image for cross)

The genotype of Jenny would be rrFf as red skin is a recessive trait that is only possible with two recessive alleles and for the freckles, there are two possible conditions, Ff and FF that can find out by crossing given in the image.

Thus, the genotype of Jenny is - rrFf

Learn more about alleles:

https://brainly.com/question/14104138