Question

A sperm cell of Equus caballus (horse) contains 32 chromosomes in its nucleus. a. How many DNA molecules would you expect in the daughter cells that result from a mitotic division of an epithelial cell of the same organism? b. How many DNA molecules does an epithelial cell of a horse contain in each one of the following phases? i. Start of interphase ii. End of interphase iii. Start of M phase iv. Metaphase c. What is the total weight of the genome of a horse epithelial cell culture that consists of 106 cells that are all in the metaphase, given that the genome of one haploid cell weighs 35ngr? d. If the length of the genome of a horse epithelial cell during metaphase is 4 x 109 base pairs, determine the length of the genome in a haploid cell of the same organism. e. How many pairs of homologous chromosomes are there in the nucleus of a somatic cell that was isolated from a male horse?

Answer 1

Answer:- a) A sperm cell of Equus cabaluus contain 32 chromosomes in it's nucleus. A daughter cell that results from the mitotic division of an epithilial cell of same organism would have 32 molecules of DNA because at the end of mitosis the two daughters cell formed are exact copies of the original organism.

b) Answer--- I) At the starting of interphase the epithilial cell of the horse will contain 32 molecules as the starting phase of interphase is G1 phase where DNA molecules remain same because replication of DNA doesn't occur in G1 phase.

b .ii) Answer---At the end of interphase the epithilial cell of the horse will be double 64 molecules of DNA will be present in the horse epithilial cell because in S phase DNA replication occurs and DNA content become double.

b.iii) Answer:-- At the start of M phase which is known as prophase the DNA molecules remain same as the DNA amount in the end of interphase that is 64 DNA molecules or 64 chromosome.

b.iv) Answer: during metaphase DNA content will be 64 DNA molecules or chromosome.

c) Answer:- Total weight of genome of horse epithilial culture = weight of genome of one haploid cell× total no. of cell

= 35 ngr× 106

= 3710 ngr.

e) Answer:- There are 16 pairs of homologous chromosome in the nucleus of somatic cell that is isolated from male horse because there is 32 total no. of chromosome and homologous pair will be half of it.