Mitosis

Question 1

What is Cell Division

Answer 1

The process by which a parent cell divides into 2 or more daughter cells.

Question 2

What is a chromosome?

Answer 2

It is a single coiled DNA molecule containing many genes.

Question 3

What are genes?

Answer 3

Genes are sections of DNA that encode genetic instructions.

Question 4

How many chromosomes are there per cell?

Answer 4

A normal body cell will contain 46 (23 pairs) of chromosomes. This number is the diploid (2n) number of chromosomes. A gamete (sex cell) will contain only 23 chromosomes. This number is the haploid (n) number of chromosomes.

Question 5

What happens during interphase?

Answer 5

1. Cell grows, stores energy and duplicates organelles.
2. The DNA replicates and the DNA content of the cell doubles. The chromosome number still remains 2n.
3. The 2 identical chromatin threads are joined together at the centromere. They are called sister chromatids.
4. The chromatin threads are in the dispersed state.

Question 6

What happens during prophase?

Answer 6

1. The chromatin condenses to form chromosomes, which are visible under the light microscope.
2. The nuclear envelope and nucleolus disappears.
3. Asters, which are structures made of microtubules, form around the centrioles.
4. The 2 centrioles move apart to opposite sides of the cell.
5. Spindle fibres extend from one pole of the cell to the other.

Question 7

What happens during metaphase?

Answer 7

1. The chromosomes line up along the metaphase plate, which is equidistant from the 2 poles.
2. The centromere of each chromosome is attached on both sides to a spindle fibre.

Question 8

What happens during anaphase?

Answer 8

1. Each pair of sister chromatids split at the centromeres and are pulled to opposite ends of the cell as the spindle fibres shorten. Each chromatid is now called a daughter chromatid.
2. The opposite ends of the cell move further apart.
3. The 2 ends of the cell now have identical collections of chromosomes.

Question 9

What happens during telophase?

Answer 9

1. Spindle fibres break down.
2. Daughter nuclei begin to form at both ends of the cell - nuclear envelope and nucleolus reform.
3. Each daughter chromatid uncoils to form chromatin threads.

Question 10

What happens during cytokinesis?

Answer 10

1. The 2 daughter cells are pinched apart.
2. Each daughter cell is a copy of the parent cell.