Fill in the blanks: We have _____ pairs of chromosomes, but for the purposes of

Question

Fill in the blanks:

We have _____ pairs of chromosomes, but for the purposes of studying meiosis, we will only look at two pairs in a cell. We’ll say that one of these pairs is long, the other is quite short.   One chromosome of each pair comes from the Dad, and the other comes from the Mom. These are __________chromosomes. This cell would be 2N = 4 so we are starting with _____ chromosomes.

We can begin with a cell that has just been formed.    As we go through __________we see the previously loosely wound DNA become the two pairs of chromosomes.    During the ______phase of Interphase we have ____________ the DNA so we have two complete sets of DNA.   This looks identical to ___________ at this point, but it is just about to change.

What happens next is that during _________ the chromosomes undergo what is called _________. The chromosome one from Mom and chromosome one from Dad are coming together and they are ______________each other really tightly and they are __________ parts of their chromosomes. In other words, the chromosomes are pretty well identical except for the changes in the genes. So they undergo what is called ____________. Segments of chromosomes from mom are switching with parts of the chromosomes from Dad. What this does is give us ___________.   The two chromosomes that we got from our two parents are combining to provide what we will deliver to our child.

At Metaphase I, we have four different ways that the chromosomes could __________ themselves. This will again provide ___________. In fact considering all 23 pairs of chromosomes, there are over eight million different possibilities.

At the end of meiosis II, there are four haploid cells formed. These cells are called __________ that may go through _____________ to become a ___________.

The reason you are special is because of the following three processes:

1. __________________________

2. __________________________

3. __________________________

Explanation / Answer

We have 23 pairs of chromosomes.

One chromosome of each pair comes from dad, and the other comes from mom. These are called homologous chromosomes. This cell would be 2N=4 so we are starting with two chromosomes.

As we go through interphase we see the preciously loosely wound DNA become the two pair of chromosomes.During S phase of interphase we have a complete copy of the DNA so we have two complete sets of DNA.

This looks identical to X shaped structure at this point but this is about to change. What happens next is that during prophase 1 the chromosomes undergo what is called homologous recombination.

The chromosomes one from mom and one from dad are coming together and they are held to each other really tightly and they are paired and replicated parts of their chromosome.

So they undergo what is called chromosomal crossover.

Segments of chromosomes from mom are switchinh with parts of the chromosomes from Dad. What this does is give us bivalents-two chromosomes and four chromatids, one chromosome from from each parent.

At Metaphase 1, we have four different ways that the chromosomes could align themselves. This will again provide haploid chromosomes(23)

These cells are called daughter cells that may go through cytokinesis(cell division) to become a polar body and an egg cell or sperm cell.

The reason you are special is because og the following three processes:-

1. Meiosis

2.Crossing over

3. Independent assortment

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