Exercise about meiosis and mitosis

[NicolasL]

Homework Statement

A cell with 16 chromosomes undergoes meiosis. One of the then formed cells (at the end of meiosis 2) gets fertilized by an unknown gamete. The zygote formed from this fertilization undergoes mitosis 3 times. How much DNA-strands will there be at the end, only taking into account the fertilized cell (so not the three other cells formed in meiosis) ?

The Attempt at a Solution

1. The cell with 16 chromosomes undergoes meiosis, so there are 4 cells with 8 chromosomes in the end.
2. One of them is fertilized by an unknown gamete, so nowe have 16 chromosomes again.
3. The formed zygote undergoes mitosis 3 times, meaning at the end there will be 2^3 cells with 16 chromosomes each.
My answer: in the end there will be 8x16 or 128 dna strands.
This seemed pretty easy to me, almost too easy, so I would like to know if I did it right. Thanks !

 

[Buzz Bloom]

Hi Nicolas:

I am not an expert, but since you have not attracted any responses yet, I thought I would offer my encouragement.

Your analysis seems right on to me.

Regards,
Buzz

 

[SciencewithDrJ]

Homework Statement

A cell with 16 chromosomes undergoes meiosis. One of the then formed cells (at the end of meiosis 2) gets fertilized by an unknown gamete. The zygote formed from this fertilization undergoes mitosis 3 times. How much DNA-strands will there be at the end, only taking into account the fertilized cell (so not the three other cells formed in meiosis) ?

The Attempt at a Solution

1. The cell with 16 chromosomes undergoes meiosis, so there are 4 cells with 8 chromosomes in the end.
2. One of them is fertilized by an unknown gamete, so nowe have 16 chromosomes again.
3. The formed zygote undergoes mitosis 3 times, meaning at the end there will be 2^3 cells with 16 chromosomes each.
My answer: in the end there will be 8x16 or 128 dna strands.
This seemed pretty easy to me, almost too easy, so I would like to know if I did it right. Thanks !

I hope this is not too late, answering after two months, because I just joined this Forum.

The question you asked is how STRANDS of DNA there are. You must be careful here. A DNA molecule has two strands (because it is a double helix, remember?). This means that there should be 2 x 8 x 16 strands of DNA. Your answer says 128 (8 x 16), but that is the number of DNA molecules, but because each molecule has TWO strands, then the answer should be 2 x 128.