The Cell Cycle

Question 1

What is mitosis?

Answer 1

Division into 2 genetically identical daughter cells and the parent cell

Question 2

What is mieosis?

Answer 2

Division into 4 unique daughter cells with 1/2 the parent cells chromosomes

Question 3

What happens in Gap 0 phase?

Answer 3

• Cells may go through apoptosis (cell death), differentiation of senescence
• Some cells may stay in this stage for a long time like neurones

Question 4

What happens in Gap 1 phase?

Answer 4

• Cells grow and increase in size
• Transcriptions of genes and to make RNA occurs
• Organelles duplicate
• Biosynthesis, protein synthesis, including making the enzymes needed for DNA replication in S phase

Question 5

What happens in S phase?

Answer 5

• When a cell reaches this point it is committed to the cell cycle
• DNA replicate
• When all chromosomes have been duplicated, each one consists of a pair of identical sister of chromatids

Question 6

What happens in Gap 2 phase?

Answer 6

Cells grow and DNA mistakes are cheked for

Question 7

What happens in M phase?

Answer 7

• Cell growth stops
• Nuclear division starts : PMAT
• Cytokinesis

Question 8

Why is S phase rapid?

Answer 8

Because the exposed DNA base pairs are more susceptible to mutagenic agents, so its speed reduces the chances of spontaneous mutations happening

Question 9

What happens in the checkpoint in M phase?

Answer 9

A chemical triggers the condensation stage in metaphase to ensure the cell is ready to complete mitosis

Question 10

What happens in the checkpoint in Gap 1 ?

Answer 10

The p53 a gene for suppressing tumours and helps control G1

Question 11

What happens in the checkpoint in Gap 2 ?

Answer 11

Special chemicals ensure the cell is ready for mitosis by stimulating proteins that will be involved in making chromosomes condense and in formation of the spindle.

Question 12

What happens in prophase?

Answer 12

• The chromosomes condenses into chromatids
• The nuclear envelope and nucleolus disappear
• The centrioles go to different poles of the cell
• The centrioles use tubulin to grow spindle fibres to connect to the centromeres

Question 13

What happens in metaphase?

Answer 13

The spindle fibres connect to the centromeres on the chromosomes and they go into the middle of the cell

Question 14

What happens in anaphase?

Answer 14

• The spindle fibres breaks up the chromatids into chromosomes
• Motor proteins shorten and pull the chromosomes towards the opposing poles

Question 15

What happens in telophase?

Answer 15

A nuclear envelope forms around the chromosomes at the 2 poles

Question 16

What happens in cytokinesis in an animal cell?

Answer 16

The cell membrane pinches in and the cytoplasm pushes it and breaks into it

Question 17

What happens in cytokinesis in a plant cell?

Answer 17

An end plate is formed from where the equator of the spindle was, and new plasma membrane and cellulose cell wall are laid down on either side along the end plate