Cell cycle regulation topic 1.6

Question 1

Cell Cycle Checkpoints

Answer 1

A cell cycle contains numerous checkpoints that ensure
the fidelity and viability of continued cell divisions

Question 2

G1 checkpoint

Answer 2

• Monitors potential growth conditions (nutrients, etc.)
• Assesses level of DNA damage (from UV, etc.)

Question 3

G2 checkpoint

Answer 3

• Monitors state of pre-mitotic cell (suitable size, etc.)
• Identifies and repairs any DNA replication errors

Question 4

Metaphase checkpoint

Answer 4

• Ensures proper alignment (prevents aneuploidy)

Question 5

Cyclins

Answer 5

proteins that control progression of the cell cycle

Question 6

Cancer

Answer 6

Cancers are diseases caused by uncontrolled cell division

Question 7

Tumors

Answer 7

Tumor cells may remain in their original location (benign)
or spread and invade neighboring tissues (malignant)

Question 8

Cancers can be caused by many different factors:

Answer 8

1. Mutagens
2. Genetics

Question 9

Mutagens

Answer 9

Mutagens are agents that change the genetic material of cells
* These agents may be either physical (e.g. UV), chemical
(e.g. arsenic) or biological in origin (e.g. certain viruses)
* Mutagens that cause cancer are classified as carcinogens

Question 10

Genetics

Answer 10

Most cancers are caused by mutations to two classes of genes:
* Proto-oncogenes stimulate cell growth and proliferation
* Tumor suppressor genes repress cell cycle progression

Question 11

The death of a cell may occur by one of two mechanisms:

Answer 11

1. Necrosis (uncontrolled ‘cell homicide’)
2. Apoptosis (programmed ‘cell suicide’)

Question 12

Necrosis

Answer 12

• The cell loses functional control due to injury, toxins, etc.
• There is a destabilization of the membranes, leading to swelling
• The cell bursts and releases its contents (causing inflammation)

Question 13

Apoptosis

Answer 13

• It is a controlled event triggered by mitochondrial proteins
• Cell contents are packaged in membranous protrusions (blebs)
• The cell fragments into apoptotic bodies which are recycled

Question 14

Smoking

Answer 14

There is a strong positive correlation between the
frequency of smoking and the incidence of cancer
* Cigarette smoke contains >60 known carcinogens