Question

In another set of mating experiments, a pink rabbit was mated to a pink rabbit and the progeny tested for RFLPs A and B and for coat color. Since both parents are heterozygous at A, B, and W, each progeny is the result of two meiosis events in which recombination COULD have occurred. a. How many meiosis events are represented in the 22 progeny shown in the table shown below? 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 Probe A 10kb 5kb TIL IIT II "MI Probe B 11kb 7 kb color pink white red pink red pink pink white pink white red pink red white pink pink red pink white pink red pink As you can see, each animal (numbers in top row) has been “phenotyped" with probe A (looking for EcoRI fragment pattern), with probe B (looking for EcoRI fragment pattern) and for color. b. Below each column (1>22), indicate that individual rabbit's GENOTYPE for gene W.

Answer 1

ANSWER A :-

1. From the above mentioned data, it can be stated that presence of two bands of a single sized probe indicates the process of crossing over as the presence of a single allele of one gene may combine with both the alleles from the other genes. In case of chromosome 2, it can be seen that there is a single band representing 5kb (A⁵) but there are two allele of B genes including (B¹¹) and (B⁷). The parental combinations would be (A¹⁰B⁷) and (A⁵B¹¹) which in this case forms the genotype namely (A⁵B⁷) which indicates crossing over has occurred. Other individual progeny includes 3, 4, 9, 10, 17,18 and 21.
2. So, in total there are 8 recombination events of Meiosis that have occurred in all the 22 individuals. Although, if the question intends to identify the number of meiotic events occurring in total, it should be double of the progeny (22 x 2 = 44) which accounts to around 44 meiotic divisions.

ANSWER B :-

1. It can be seen that the allele for red color is dominant and the allele for white color is recessive. The pink color is an output of incomplete dominance. If this is the case, it can be stated that the red color will be dominant and the white color will be recessive. Or in other way round, the white color seems to be dominant in rabbits and hence red color can be considered as recessive.

1

2

3

4

5

6

7

8

9

10

11

12

13

14

15

16

17

18

19

20

21

22

color

pink

white

red

pink

red

pink

pink

white

pink

white

red

pink

red

white

pink

pink

red

pink

white

pink

red

pink

genotype 1

Ww

WW

ww

Ww

ww

Ww

Ww

WW

Ww

WW

ww

Ww

ww

WW

Ww

Ww

ww

Ww

WW

Ww

ww

Ww

genotype 2

Ww

ww

WW

Ww

WW

Ww

Ww

ww

Ww

ww

WW

Ww

WW

ww

Ww

Ww

WW

Ww

ww

Ww

WW

Ww

There are two genotypes mentioned depending upon two different aspects of dominant and recessive alleles. For any doubts, please prefer communicating through the comment section.