8.3 Controlling cell division

Question 1

What is the purpose of cell cycle checkpoints?

Answer 1

To ensure things are correct before moving to the next stage.

Question 2

What are the 3 cell cycle checkpoints?

Answer 2

• G1
• G2
• Metaphase (M)

Question 3

What is the purpose of the checkpoint at the end of G1?

Answer 3

To ensure that:

• There are enough resources to divide
• The cell is big enough
• The DNA is undamaged

Question 4

What is the purpose of the checkpoint at the end of G2 (similar to G1)?

Answer 4

To ensure that:

• There are enough resources to divide
• The cell is big enough
• The DNA is undamaged
• To check that the chromosomes have been correctly replicated

Question 5

What is the purpose of the checkpoint at the end of metaphase?

Answer 5

To ensure that:

• The spindle fibres have connected to the sister chromatids and centromeres
• The chromosomes are lined up in the middle

Question 6

What are the 2 types of cell death?

Answer 6

• Apoptosis

- Necrosis

Question 7

What is apoptosis (programmed cell death)?

Answer 7

A series of events which result in the dismantling of the internal contents of a cell.

Question 8

What is apoptosis triggered by?

Answer 8

1. Death signals

2. Withdrawal of survival factors

Question 9

What is necrosis?

Answer 9

The sudden violent death ‘explosion’ of a cell if it is physically damaged or starved of oxygen.

Question 10

Name the 3 genetic factors of why cancer occurs?

Answer 10

• Proto-oncogenes
• Tumor-suppressor genes
• Inherited genes

Question 11

What are proto-oncogenes?

Answer 11

Cells involved in controlling the cell cycle that if mutated, continually divides.

Question 12

What are tumour-suppressor genes?

Answer 12

A group of proteins that tell the cell to slow down cell division, that if mutated, is unable to stop cell division.

Question 13

What are inherited genes?

Answer 13

Genes that increase the risks of a particular type of cancer.

Question 14

Name the 3 environmental factors of why cancer occurs?

Answer 14

• Chemicals
• Physical damage
• Biological damage

Question 15

Give examples of chemicals that can cause cancer:

Answer 15

• Compounds in tobacco
• Some pesticides
• Industrial chemicals
• Asbestos

Question 16

Give examples of physical damage that can cause cancer:

Answer 16

• X-rays which can cause mutations of DNA

- UV light from the sun or tanning beds can cause skin cancer

Question 17

Give examples of biological damage that can cause cancer:

Answer 17

-Viruses can cause certain types of leukaemia

Question 18

What causes neoplasms (tumours)?

Answer 18

Uncontrolled cell division in adults.

Question 19

Name the 2 main types of neoplasms (tumours):

Answer 19

• Benign
• Potentially malignant
• Malignant

Question 20

What are benign neoplasms?

Answer 20

Local mass of cells but do not turn into cancer

Question 21

What are malignant neoplasms?

Answer 21

Masses that migrate to other locations causing cancer and organ disruption.

Question 22

What can happen if apoptosis fails?

Answer 22

It can result in cancers and autoimmune diseases.

Question 23

What can happen when there is too much apoptosis?

Answer 23

It can cause a large number of nerve cells to be lost, which may lead to conditions such as Alzheimer disease.

Question 24

What can happen if the telomeres of a chromosome become too short?

Answer 24

The cell no longer divides or it goes into apoptosis.

Question 25

What are potentially malignant neoplasms?

Answer 25

Tumours that will turn into cancer and move to invade other tissues if left

Question 26

Explain the process of apoptosis:

Answer 26

- Normal cell - Formation of blebbing - The cell breaks apart - No inflammation

Question 27

Explain the process of necrosis:

Answer 27

- Normal cell - Cell swells - Plasma membrane ruptures. - The cell inflames