3.8- THE CELL CYCLE

Question 1

Do all cells in multicellular organisms retain the ability to divide?

Answer 1

no

Question 2

What do the cells that do not divide continuously do?

Answer 2

undergo regular cycle of division separated by periods of cell growth

Question 3

What are the 3 stages of the cell cycle?

Answer 3

interphase
nuclear division
division of cytoplasm (cytokinesis)

Question 4

How long is interphase in the cell cycle?

Answer 4

occupies most of the cell cycle

Question 5

What is interphase sometimes known as?

Answer 5

resting phase

Question 6

Why is interphase sometimes known as resting phase?

Answer 6

no division takes place

Question 7

What is nuclear division?

Answer 7

when nucleus divides either into two (mitosis) or four (meiosis)

Question 8

What does cytokinesis follow?

Answer 8

nuclear division

Question 9

What is cytokinesis the process of?

Answer 9

cytoplasm divides to produce two new cells (mitosis) or four new cells (meiosis)

Question 10

Typically, how long does it take for the complete cell cycle in a mammalian cell?

Answer 10

takes about 24 hours

Question 11

What percentage of the cell cycle in mammalian cell cycle is interphase?

Answer 11

90%

Question 12

What is cancer?

Answer 12

group of diseases (around 200 in total) caused by a growth disorder of cells

Question 13

What is cancer result of?

Answer 13

damage to genes that regulate mitosis + cell cycle

Question 14

What does damage to genes that regulate mitosis + cell cycle cause?

Answer 14

uncontrolled growth + division of cells

Question 15

What does uncontrolled growth + division of cells form?

Answer 15

group of abnormal cells, called a tumour, develops + constantly expands in size

Question 16

Where can tumours develop?

Answer 16

in any organ of the body

Question 17

Where are tumours most commonly found? (8)

Answer 17

lungs 
prostate gland (male)
breast
ovaries (female)
large intestine
stomach
oesophagus 
pancreas

Question 18

How does a tumour become cancerous?

Answer 18

changes from being benign to malignant

Question 19

How do most cells divide?

Answer 19

by mitosis

Question 20

Why do most cells divide by mitosis? (2)

Answer 20

increase size of tissue during development (growth)

replace dead + worn out cells (repair)

Question 21

What can the rate of mitosis be affected by? (2)

Answer 21

environment of cell

growth factors

Question 22

What is mitosis controlled by?

Answer 22

two types of genes

Question 23

What can a mutation in one of the two types of genes controlling mitosis do?

Answer 23

results in uncontrolled mitosis

Question 24

In what ways can the cell be different be due to a mutation in a gene controlling mitosis?

Answer 24

structurally and functionally different from normal cells

Question 25

What happens to most mutated cells?

Answer 25

most mutated cells die

Question 26

What are mutated cells that survive able to do?

Answer 26

capable of dividing to form clones of themselves + forming tumours

Question 27

Description of malignant tumours (3)

Answer 27

grow rapidly
less compact
more likely to be life-threatening

Question 28

Description of benign tumours (3)

Answer 28

grow more slowly
more compact
less likely to be life-threatening

Question 29

What does the treatment of cancer often involve?

Answer 29

killing dividing cells by blocking a part of the cell cycle

Question 30

What happens as parts of the cell cycle is blocked in cancer treatment?

Answer 30

cell cycle disrupted + cell division + hence cancer growth ceases

Question 31

What is a drug treatment for cancer?

Answer 31

chemotherapy

Question 32

How do drugs used to treat cancer usually disrupt the cell cycle? (2)

Answer 32

preventing DNA from replicating

inhibiting metaphase stage of mitosis by interfering with spindle formation

Question 33

What is problem of drugs used to treat cancer?

Answer 33

also disrupt cell cycle of normal cells

Question 34

What are drugs used to treat cancer more effective against?

Answer 34

rapidly dividing cells

Question 35

To what extent are cancer cells damaged in comparison to normal cells by drugs for cancer treatment?

Answer 35

damaged to a greater degree than normal cell

Question 36

What is the rate of division for cancer cells?

Answer 36

fast rate of division

Question 37

What type of normal body cell is vulnerable to damage by drugs in cancer treatment?

Answer 37

hair-producing cells

Question 38

Why are hair-producing cells vulnerable to damage by drugs in cancer treatments?

Answer 38

they divide rapidly

Question 39

As hair-producing cells are vulnerable to damage from drugs in cancer treatment what does this explain?

Answer 39

hair loss frequently seen in patients undergoing cancer treatment