Question

Merle is a marking pattern in canine coats that appears as a marbling of color in a solid coat. The merle gene displays incomplete dominance.
CSCS individuals display a solid coat
CMCS individuals are merle and show patches of fur with a lighter, mottled effect
CMCM individuals are "double merle" and show patches of fur with much more pronounced lightening
Another gene, FGF5, also influences coat phenotype and determines whether dogs display long or short coats, with short coats being dominant to long coats.
A. Determine the proportion of offspring phenotypes that would result when two merle dogs mate, if one dog is true-breeding for the long-coat trait and the other dog is true-breeding for the short-coat trait.
a. 0
b. 1/16
c. 1/8
d. 3/16
e. 1/4
f. 3/8
g. 1/2
h. 3/4
1. double merle with short coat:___.
2. double merle with long coat:___.
3. merle with short coat:___.
4. merle with long coat:___.
5. solid with short coat:___.
6. solid with long coat:____.
B. Determine the proportion of offspring phenotypes that would result when two merle dogs mate, if both dogs are heterozygous(Ll) for the gene that regulates coal length.
a. 0
b. 1/16
c. 1/8
d. 3/16
e. 1/4
f. 3/8
g. 1/2
h. 3/4
1. double merle with short coat:___.
2. double merle with long coat:___.
3. merle with short coat:___.
4. merle with long coat:___.
5. solid with short coat:___.
6. solid with long coat:____.

Answer 1

Answer:

A)

1. double merle with short coat: 1/4 (e).

2. double merle with long coat: 0 (a).

3. merle with short coat: 1/2 (g).

4. merle with long coat: 0 (a).

5. solid with short coat: 1/4 (e).

6. solid with long coat: 0 (a).

B)

1. double merle with short coat: 3/16 (d).

2. double merle with long coat: 1/16 (b)

3. merle with short coat: 3/8 (f).

4. merle with long coat: 1/8 (c).

5. solid with short coat: 3/16 (d).

6. solid with long coat:1/16 (b)

Explanation:

Available data:

• CSCS individuals display a solid coat
• CMCS individuals are merle and show patches of fur with a lighter, mottled effect
• CMCM individuals are "double merle" and show patches of fur with much more pronounced lightening
• short coats, L-,  being dominant to long coats, ll.
• Cross: merle long-coated dog x merle short-coated dog

Parentals) CMCS  ll      x       CMCS LL

Gametes) CMl, CSl, CMl, CSl

                 CML, CSL, CML, CSL

Punnett square)      CMl           CMl            CSl            CSl

             CML     CMCM Ll    CMCM Ll    CMCS Ll    CMCS Ll

             CML     CMCM Ll    CMCMLl     CMCS Ll    CMCS Ll

             CSL      CMCS Ll     CMCS Ll     CSCS Ll     CSCS Ll

             CSL      CMCS Ll     CMCS Ll     CSCS Ll     CSCS Ll

F1) 4/16 = 1/4 = 25% CMCM Ll, double merle short-coated individuals

    4/16 = 1/4 = 25% CSCS Ll, solid short-coated individuals

    8/16 = 1/2 = 50% CMCS Ll, merle chort-coated

• Cross: merle short-coated dog  x  merle short-coated dog

Parentals)   CMCS Ll      x       CMCS Ll

Gametes)  CML, CMl, CSL, CSl, CML, CMl, CSL, CSl

Punnett square)     CML           CMl             CSL           CSl

                CML    CMCM LL   CMCM Ll    CMCS LL   CMCS Ll

                CMl     CMCM Ll     CMCM ll     CMCS Ll    CMCS ll

                CSL     CMCS LL     CMCS Ll    CSCS LL    CSCS Ll

                CSl      CMCS Ll      CMCS ll      CSCS Ll     CSCS ll

F1) 1/16 CMCM LL, double merle short-coated individual

    2/16 CMCM Ll, double merle short-coated individual

    1/16 CMCM ll, double merle long-coated individual

    2/16 = 1/8 CMCS LL, merle short-coated individual

    4/16 = 2/8 CMCS Ll, merle short-coated individual  

    2/16 = 1/8 CMCS ll, merle long-coated individual

    1/16 CSCS LL, solid short-coated individual

    2/16 = 1/8 CSCS Ll, solid short-coated individual

    1/16 CSCS ll, solid long-coated individual