Chapter 13: Viruses - Cancer

Question 1

What is a tumor?

Answer 1

• abnormal growth of tissue

Question 2

What is a benign tumour?

Answer 2

does not spread

Question 3

What is a malignant tumour?

Answer 3

• metastasize and invade nearby tissues (cancer)

Question 4

What two genes control cell growth of cancer?

Answer 4

• proto-oncogenes
• tumor-supressor genes

Question 5

What are proto-oncogenes?

Answer 5

• genes that stimulate cell growth

Question 6

What are tumor-supressor genes?

Answer 6

• genes that inhibit cell growth

Question 7

What do mutations in proto-oncogenes and tumor-supressor genes cause?

Answer 7

• leads to uncontrolled cell growth, tumor formation, and cancer

Question 8

What are cancer causing viruses (oncogenic viruses)?

Answer 8

• carry oncogenes, which are genes that interfere with the cell’s control mechanisms
• most are DNA viruses

Question 9

Most oncogenic viruses are DNA viruses. What are DNA viruses? (2)

Answer 9

• integrate viral DNA into the host xme as a provirus
• oncogenes continue to be supressed (grow indefinitely)

Question 10

What is believed to be the cause of almost all cases of liver cancer?

Answer 10

Hep B and C

Question 11

What is Epstein-Barr virus?

Answer 11

• causes infectious mononucleosis
• may cause lymphoma (cancer of WBC) and some cancers of the nose and throat

Question 12

What is Human Papillomavirus (HPV)? (3)

Answer 12

• STD
• genital warts
• believed to cause almost all cases of cervical cancer (abnormal growth in reproductive system)

Question 13

In lecture, Hep C is an ___ RNA/DNA virus?

Answer 13

RNA

Question 14

In lecture, what is the most common STD

Answer 14

HPV

Question 15

What are two virus-like infectious particles?

Answer 15

• viroids
• prions

Question 16

What are viroids? (3)

Answer 16

• naked RNA
• No protein coat
• results in some diseases in plants, but not yet found in animals

Question 17

What are prions? (3)

Answer 17

• infectious protein particles
• No genetic material (RNA/DNA)
• linked to several human and animal diseases

Question 18

Give an example of disease caused by prions. (2)

Answer 18

Transmissible spongiform encephalopathies
- causes sponge-like holes in the brain

Question 19

What is the mode of infection for prions?

Answer 19

• transmitted through food

Question 20

What is the name of disease when these animals are infected by prions?
1) sheep
2) Cow
3) humans

Answer 20

sheep - scrapie
cow - mad cow disease
humans - variant creutzfeldt-Jakob disease

Question 21

How can prions be destroyed? (2)

Answer 21

• not usually destroyed by high temperatures
• can be destroyed by heat (480C) or a combination of autoclaving in a solution of sodium hydroxide (base

Question 22

How long does disease caused by prions last in humans? why?

Answer 22

• onset of disease in humans occurs several years after infection
• not clear why or how it accumulates in the brain

Question 23

Why are prions so dangerous to us? (2)

Answer 23

• always fatal
• no cure or treatment

Question 24

In lecture, why do prions occur?

Answer 24

• we all have forms of PrPc and the gene that codes forit causes a mutation
• instead of producing PrPc, the gene mutates and produces PrPsc