Th cell cycle

Question 1

State the stages of the cell cycle in order

Answer 1

• Interphase
• Mitosis
• Cytokinesis

Question 2

What’s the longest stage called

Answer 2

Interphase

Question 3

Describe what happens during interphase

Answer 3

To prepare for division:
- The cell grows as the volume of the cytoplasm increases
- The cell replicates it’s DNA
- The cell replicates the organelles and increases ATP synthesis

Question 4

Describe the process of mitosis

Answer 4

• During Prophase, the nuclear envelope breaks down, chromosome condense, centrioles move to opposite poles and produce spindle fibres
• During Metaphase, Chromosomes move to the middle of the cell and spindle fibres attach to the centromere of each chromosome
• During anaphase, Chromosomes move to opposite sides of the cell, when the centromeres divide and the spindle fibres contract, with the energy provided by ATP
• During Telophase, Spindle fibres break down, and the nuclear envelope reforms.

Question 5

Describe the process of cytokinesis

Answer 5

The cytoplasm divides, and the cell membrane reforms to produce 2 identical daughter cells

Question 6

In which stage do new cell membranes form

Answer 6

Interphase

Question 7

In which stages can you see the nucleus

Answer 7

Interphase and Cytokinesis

Question 8

Why can’t you see the nucleus in mitosis

Answer 8

The nucleus breaks down in prophase

Question 9

In which stages can you see the Chromosomes. Explain why

Answer 9

• Mitosis
• They condense

Question 10

In which stage do DNA helicase and DNA polymerase act. Explain why

Answer 10

• Interphase
• They catalyse DNA replication, which happens during interphase

Question 11

Describe what is meant by cancer and how it is caused

Answer 11

• Cancer is uncontrollable cell division
• Caused by DNA mutations, which affect the genes that regulate the cell cycle, causing the cell cycle to occur more quickly, and so cells divide uncontrollably

Question 12

Define tumour

Answer 12

Masses of rapidly dividing cells

Question 13

Describe how tumours cause harm

Answer 13

They exert pressure on organs, and create blockages

Question 14

What are the 2 types of tumours, and describe the difference between them

Answer 14

• Malignant and benign
• Malignant can spread, whereas benign cannot

Question 15

What are the 2 genes that regulate the cell cycle called

Answer 15

• Protooncogenes
• Tumour suppressor genes

Question 16

Describe the difference between the 2 genes that regulate the cell cycle

Answer 16

Protooncogenes stimulate the cell cycle, whereas tumour suppressors prevent the continuation of the cell cycle

Question 17

Describe how Protooncogenes stimulate cell division

Answer 17

When a growth factor binds to a receptor on the cell membrane, the protooncogene is switched on, and the cell divides

Question 18

What do we call a protooncogene when it mutates

Answer 18

Oncogene

Question 19

Describe the properties and function of Oncogenes

Answer 19

• Oncogenes are permanently switched on
• The rate of cell division increases uncontrollably as the cell divides even when growth factors are absent

Question 20

Describe the function of tumour suppressor genes

Answer 20

• Tumour suppressor genes produce proteins, which either repair damaged DNA, or cause cells with damaged DNA to self destruct (apoptosis)

Question 21

Describe what happens when the tumour suppressor genes mutate

Answer 21

• They no longer function correctly
• Cells with damaged DNA continue to divide, which can lead to cancer

Question 22

What do cancer drugs aim to do

Answer 22

• Prevent DNA replication
• Prevent spindle fibre formation

Question 23

Why is it difficult to treat cancer

Answer 23

• It’s difficult to treat cancer without harming healthy cells, and so cancer treatments often have many side effects
• This is why quickly replicating cells, such as hair cells and immune cells are particularly affected

Question 24

What are the 3 stages of interphase

Answer 24

G1 (growth)
S (synthesis)
G3 (growth)