Question

If we ignore the effect of crossing over how many different haploid cells arise in meiosis in a diploid cell having 2n=12?

A)16

B)8

C)32

D)64

I need the explanation too:)

Answer 1

Let us start answering your question by taking a condition where a cell have 2n=4 i.e. 2 pair of chromosome. For simplicity let us call the chromosomes as A-A' and B-B', where A and A' are homologous chromosome and so are B and B'. Now if this cells undergo meiosis, then the chromosome would segregate into four different cells. Each cell would have one of the either homologous chromosome i.e one from the A pair and one from B pair.

So the different way they could be seen in cell is A-B, A-B', A'-B and A'-B'.
Similarly if there was three pair of chromosome then 8 different types could be seen.
So for n=2, types of haploid cells resulting from meiosis = 2^n

And hence for n=6 (or 2n=12) the type of different cells without crossing over =2^6=64 kinds