Chromosomes and Mitosis

Question 1

What are chromosomes?

Answer 1

Coiled up lengths of DNA molecules.

Question 2

What does each chromosome carry?

Answer 2

A large number of genes.

Question 3

What do different genes control?

Answer 3

The development of different characteristics.

Question 4

What do body cells have regarding chromosomes?

Answer 4

They have two copies of each chromosome - one from the organism’s “mother”, and one from its “father”.

Question 5

What happens in the mitosis part of the cell cycle?

Answer 5

Body cells in multicellular organisms divide to produce new cells.

Question 6

What do multicellular organisms use mitosis for?

Answer 6

To grow or replace cells that have been damaged.

Question 7

What is the result at the end of the cell cycle?

Answer 7

Two new cells identical to the original cell, with the same number of chromosomes.

Question 8

What are the stages of the Growth and DNA Replication (first) part of the cell cycle?

Answer 8

1. In a cell that’s not dividing, the DNA is all spread out in long strings. 2. Before it divides, the cell has to grow and increase the amount of subcellular structures such as mitochondria and ribosomes. 3. It then duplicates its DNA - so there’s one copy for each new cell. The DNA is copied and forms X-shaped chromosomes. Each “arm” of the chromosome is an exact duplicate of the other. (Once its contents and DNA have been copied, the cell is ready for mitosis).

Question 9

What are the stages of Mitosis in the cell cycle?

Answer 9

4. The chromosomes line up at the centre of the cell and cell fibres pull them apart. The two arms of each chromosome go to opposite ends of the cell. 5. Membranes form around each of the sets of chromosomes. These become the nuclei of the two new cells - the nucleus has divided. 6. The cytoplasm and cell membrane divide.
   The cell has produced two new daughter cells. The daughter cells contain the same DNA - they’re identical. Their DNA is also identical to the parent cell.