Mating between a male donkey (2 n =62) and a female horse (2 n =64) produces ste
ID: 215728 • Letter: M
Question
Mating between a male donkey (2n=62) and a female horse (2n=64) produces sterile mules. Recently, however, a very rare event occurred-a female mule gave birth to an offspring by mating with a horse.
QUESTION #1: Determine how many chromosomes are in the mule karyotype. Express your answer as an integer. Can you please show the work, on how to do it.
QUESTION #2: How many chromosomes does the mule-horse offspring carry? See image below for this question.
A) 64 B) 63 or 64 C) 62 or 63 D) 62 or 64 E) 63 F) 62 G) 62, 63, and 64 are all possible.Explanation / Answer
1. For female Horse, 2n= 64. Hence, n=64/2 = 32
For male donkey 2n=62. Hence n=62/2= 31.
So, the mule will be fusion of two gametes containing 31 and 32 chromosomes respectively. So total chromosomes of a mule will be 2n= 31+32 =63.
2. Now, the mule has 63 chromosomes as 2n number. It is not possible that during gamete formation one chromosome will split into halves and form a pair of broken chromosomes. So here the situation is little bit different. Mule will produce two types of gamete. One will have 31 and another one will have 32 chromosomes (31 +32 = 63). It is due to unequal distribution of chromosomes during meiosis. So by this, each of the daughter cell i.e., that gamete formed by mule will have different number of chromosomes.
Now the male horse carries 64 chromosomes as 2n number. The gamete formed from horse body will have 32 chromosomes (n number).
This 32 chromosome containing gamete of horse can bind to either of those previous two gametes formed by female mule.
So the offspring will have either 31(mule gamete)+32(horse gamete) = 63
or
32(mule gamete)+32(horse gamete)=64 chromosomes. So option B is correct.