Mod. 2 cell division (cell cycle and mitosis)

Question 1

What happens during normal cell cycle interphase?

Answer 1

Normal cell metabolic processes
DNA is replicated and checked for errors
Protein synthesis in cytoplasm
Mitochondria grow and divide
Chloroplasts grow and divide in plants and algae

Question 2

What are the three stages of cell cycle interphase (cell division)?

Answer 2

G1 - growth phase 1
S - synthesis phase
G2 - growth phase 2

Question 3

What happens in the cell cycle G1 phase?

Answer 3

Growth phase 1. All the organelle proteins are synthesised and the organelles replicate. The cell increases in size.

Question 4

What happens in the cell cycle S phase?

Answer 4

Synthesis phase. DNA is replicated in the nucleus.

Question 5

What happens in the cell cycle G2 phase?

Answer 5

Growth phase 2. Cell continues to increase in size. Energy stores are increased. DNA checked for errors.

Question 6

What are the two stages of the cell cycle mitotic phase?

Answer 6

mitosis

cytokinesis

Question 7

What happens in the cell cycle mitosis phase?

Answer 7

The nucleus divides.

Question 8

What happens in the cell cycle cytokinesis phase?

Answer 8

the cytoplasm divides and two cells are produced.

Question 9

What happens in the cell cycle G0 phase?

Answer 9

The cell leaves the cell cycle because of differenciation, damaged DNA or aging. Some cells can be stimulated to go back.

Question 10

What are the checkpoints during mitosis?

Answer 10

G1 checkpoint - at the end of growth phase just before the DNA is replicated. If failed, it enters G0 phase.
G2 checkpoint - end of second growth phase. DNA is checked for errors. If passed, mitosis is activated.
Spindle assembly (metaphase) checkpoint - Spindle fibres must be aligned. Mitosis proceeds.

Question 11

Chromosome

Answer 11

A molecule of DNA, one or two chromatids can make up a chromosome

Question 12

Chromatid

Answer 12

DNA molecule, but when the DNA is replicated, there are two chromatids attached at the centromere

Question 13

Centromere

Answer 13

Region where two chromatids are joined together. It allows DNA to be organised easily by keeping identical chromatids together.

Question 14

What are the stages of mitosis?

Answer 14

prophase
metaphase
anaphase
telophase

Question 15

What happens in prophase?

Answer 15

1st stage of mitosis.
Chromatin fibres (DNA and RNA) coil and condense into visible chromosomes. Nucleolus disappears. Nuclear membrane begins to break down.
Protein microtubules form spindle fibres at poles of the cell. In animals, centrioles move with them.
Spindle fibres attach to specific points of centriole and begin to organise chromosomes.

Question 16

What happens in metaphase?

Answer 16

2nd stage of mitosis

chromosomes are moved by spindle fibres to line up on the metaphase plate.

Question 17

What happens in anaphase?

Answer 17

3rd stage of mitosis

Centromeres divide, the chromatids are separated and pulled to opposite poles of the cell.

Question 18

What happens in telophase?

Answer 18

4th stage of mitosis

Chromatids at the poles, now called chromosomes. Nuclear envelope reforms around them. Chromosomes start to uncoil.

Question 19

What happens in cytokinesis in animal cells?

Answer 19

5th stage of mitosis

Cleavage furrow forms in middle of the cell. Cytoskeleton pulls the csm inwards until they are close enough to fuse.

Question 20

What happens in cytokinesis in plants?

Answer 20

5th stage of mitosis

Vesicles from Golgi apparatus assemble and begin to fuse at location of metaphase plate.