Chapter 16

Question 1

Because they act to _______ tumorigenesis, the miR-15a and miR-16 miRNAs can be thought of as _________.

Answer 1

inhibit, tumor suppressors

Question 2

When oxygen is plentiful, ___________.
A) lactic acid is secreted into the tumor’s microenvironment
B) tumor growth may be promoted by lactic acid
C) tumor cells still continue to generate much of their ATP by glycolysis
D) all of these answers are correct

Answer 2

all of these answers are correct

Question 3

Oncogenes act _______; one copy of the gene ________, regardless of whether or not there is a normal, unactivated copy of the gene on the homologous chromosome.

Answer 3

dominantly, makes the cell express the altered phenotype

Question 4

Which of the following types of gene product are encoded by tumor-suppressor genes?
A) transcription factors
B) components that regulate G proteins
C) all of these answers are correct
D) a protein that regulates protein degradation

Answer 4

all of these answers are correct

Question 5

What is unusual about the inheritance of retinoblastoma, given that it appears to be inherited as a dominant trait?

Answer 5

Not all children who inherited the RB deletion developed retinoblastoma.

Question 6

What happens if one cultures cells from a tumor lacking a functional RB gene after reintroducing a wild-type copy of the gene into those cells?

Answer 6

The cancer phenotype disappears.

Question 7

Which of the following treatments would cause an increase in p53 protein levels in a G1 cell?
A) exposure to chemical carcinogens
B) injection of a cell with DNA containing broken strands
C) exposure to ultraviolet light
D) all of these are correct answers

Answer 7

all of these are correct answers

Question 8

Why would mutated APC genes be likely to lead to abnormal chromosome segregation and aneuploidy?

Answer 8

The APC gene may play a role in microtubule attachment to the kinetochores of mitotic chromosomes; thus a mutated APC gene would cause chromosomes to segregate abnormally.

Question 9

The BCL-2 oncogene is the oncogene most closely linked to _________; it encodes a membrane-bound ____________.

Answer 9

apoptosis, protein that normally acts to inhibit apoptosis

Question 10

What are the consequences for tumors that metastasize?
A) They can invade surrounding healthy tissu
B) All of these answers are correct.
C) They are harder to treat.
D) They are more deadly.

Answer 10

All of these answers are correct.

Question 11

Cancer is a genetic disease in that it can be traced to alterations within specific genes, but, in most cases, it is not an inherited disease. Why is that the case?

Answer 11

The genetic alterations in most cancers arise mostly in the DNA of somatic cells during the lifetime of the affected individual.

Question 12

Cancer is characterized by _____________.
A) the invasion of surrounding healthy tissues
B) formation of malignant tumors
C) uncontrollable cell proliferation
D) all of these answers are correct

Answer 12

all of these answers are correct

Question 13

Which statement below is a correct statement about the abilities of normal cells and cancer cells to grow and divide when cultured under conditions favorable for cell proliferation?

Answer 13

Malignant and normal cells grow and divide at similar rates.

Question 14

What enzyme possessed by cancer cells, but lacking in normal cells, is thought to contribute to the ability of cancer cells to divide indefinitely and to exhibit a seeming immortality?

Answer 14

telomerase

Question 15

What appears to be the cause of aneuploidy in cancer cells?

Answer 15

defects in the mitotic checkpoint

Question 16

All of the following are considered causes of cancer EXCEPT \_\_\_\_\_\_\_\_.
A) Environmental agents 
B) DNA and RNA tumor viruses 
C) Ionizing radiation 
D) Microwave radiation

Answer 16

Microwave radiation

Question 17

____________ is a rare childhood cancer of the eye’s retina.

Answer 17

Retinoblastoma

Question 18

What is the oncogene that is most often mutated in human tumors and what does it encode?

Answer 18

the RAS gene, a GTP-binding protein that serves as an on-off switch for a key cell signaling pathway that controls cell proliferation

Question 19

Because they act to _______ tumorigenesis, the miR-15a and miR-16 miRNAs can be thought of as _________.

Answer 19

inhibit, tumor suppressors

Question 20

What part of the cell cycle does the pRB protein help to regulate?

Answer 20

the G1 - S transition