Math  /  Algebra

Question10. A fruit fly is an F1F_{1} offspring of two true-breeding parents for body color and wing length (GGLL ×\times ggll). The F1F_{1} fly is a heterozygote for both gray body and long wings (GgLI). The heterozygous fly mates with a beautiful female that is stunningly homozygous recessive for body color (black) but homozygous dominant for wing length (long). What are the phenotypes and genotypic ratio of the F2\mathrm{F}_{2} offspring from this mating? Remember that the genes for body color and wing length are linked! F2F_{2} phenotypes: \qquad \qquad F2F_{2} genotypic ratio: \qquad

Studdy Solution

STEP 1

What is this asking? We need to figure out what kinds of offspring (F2F_{2}) and in what ratios, a gray-bodied, long-winged fly (GgLlGgLl) and a black-bodied, long-winged fly (ggLLggLL) can produce, knowing that the genes for body color and wing length are linked. Watch out! Linked genes don't follow the typical Mendelian inheritance patterns, so be careful!
We can't just do a simple Punnett square here.

STEP 2

1. Determine the possible gametes.
2. Set up the Punnett square.
3. Determine the phenotypes and genotypic ratio.

STEP 3

Since the genes are linked, they're inherited together!
Our first fly (GgLlGgLl) can produce two types of gametes: GLGL and glgl.

STEP 4

Our stunning second fly (ggLLggLL) can also produce two types of gametes: gLgL and gLgL.
Notice it produces the same gamete twice since it's homozygous for both traits.

STEP 5

Let's **draw** our Punnett square.
We'll put the first fly's gametes (GLGL and glgl) along the top and the second fly's gametes (gLgL and gLgL) down the side.
gLgLGLGgLLGgLLglggLlggLl\begin{array}{cc} & gL & gL \\ GL & GgLL & GgLL \\ gl & ggLl & ggLl \\ \end{array}

STEP 6

Let's look at the **genotypes** in our Punnett square.
We have two GgLLGgLL and two ggLlggLl.
This simplifies to a **1:1 genotypic ratio**.

STEP 7

Now, let's figure out the **phenotypes**. GgLLGgLL means gray body and long wings. ggLlggLl means black body and long wings.

STEP 8

So, we have two gray-bodied, long-winged flies and two black-bodied, long-winged flies.
This gives us a **1:1 phenotypic ratio**.

STEP 9

F2F_{2} phenotypes: Gray body, long wings and Black body, long wings
F2F_{2} genotypic ratio: 1 GgLLGgLL : 1 ggLlggLl

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