Deck 3: Tumor Viruses

Question 1

A gene found in a normal cell's genome that can be picked up and altered by a virus to drive cellular transformation is known as

A)An oncogene
B)A proto-oncogene
C)A transgene
D)A protogene
E)None of the above

Answer 1

A proto-oncogene

Question 2

Scientists may map the insertion sites of viruses in DNA isolated from tumors that formed following retroviral infection in order to

A)Identify the viral genes responsible for transformation.
B)Discover new proto-oncogenes.
C)Determine how viruses suppress tumorigenesis.
D)Understand how viruses infect cells.
E)All of the above.

Answer 2

Discover new proto-oncogenes.

Question 3

Which of the following is true of c-src?

A)It is present only in vertebrate cells containing integrated viral DNA.
B)It results in cellular transformation.
C)It is an example of a proto-oncogene.
D)It is highly conserved among vertebrate species.
E)C and D.

Answer 3

C and D.

Question 4

The ability of cells suspended in soft semi-solid)agar medium to form colonies is a good predictor that

A)These cells will form tumors if injected subcutaneously into immunocompromised mice.
B)These cells have stopped proliferating and will die.
C)These cells would fail to grow in normal medium.
D)These cells have an increased requirement for growth factors.
E)None of the above.

Question 5

Which of the following enzymes are encoded by retroviral DNA?

A)Integrase.
B)Reverse transcriptase.
C)RNA polymerase II.
D)A and B.
E)None of these enzymes are encoded by retroviral DNA.

Question 6

Which of the following is true of retroviruses?

A)They are DNA viruses.
B)Their replication cycle requires DNA to be transcribed to RNA.
C)The DNA versions of their viral genomes are called proviruses.
D)B and C.
E)None of the above.

Question 7

Which of the following is a property of transformed cells?

A)Rounded shape
B)Reduced requirement for mitogenic growth factors
C)Loss of contact inhibition
D)Increased transport of glucose
E)All of the above

Question 8

Some retroviruses are able to transform cells through

A)Inserting themselves near a proto-oncogene in the host genome.
B)Acquiring oncogenes within their own genome.
C)Possessing genes that specify proteins that activate cellular genes involved in proliferation.
D)A,B,and C.
E)None of the above.

Question 9

Which of the following is considered to be a tumor virus?

A)Hepatitis B virus HBV)
B)Human papillomavirus HPV)
C)Shope fibroma virus
D)Human adenovirus 5
E)All of the above

Question 10

Once a cell has been infected with a virus,how might viral genes be transmitted from mother to daughter cells?

A)Viral DNA carries its own replication machinery,replicating its own genome independently of host enzymes.
B)Viral DNA may be integrated into the host cell's chromosomes,so that it is replicated along with host DNA prior to cell division.
C)Viral DNA may be linked to host DNA through protein bridges,allowing it to tag along with host chromosomal DNA during cell division.
D)B and C.
E)All of the above.

Question 11

Experiments using temperature-sensitive mutants of RSV to infect chicken embryo fibroblasts demonstrated that

A)Infection with RSV is necessary to initiate transformation of these cells,but the RSV genome is not needed to maintain the transformed state.
B)The RSV transforming gene is necessary for both the initiation and maintenance of transformation in these cells.
C)Infection with RSV alone is unable to transform these cells.
D)Cells infected with RSV continue to exhibit normal cellular morphology.
E)None of the above.

Question 12

Dulbecco and Rubin discovered that they could infect chicken embryo fibroblasts with RSV in culture.Which of the following was NOT a characteristic exhibited by these cells after they were infected?

A)Virus particles were produced by these cells for many weeks.
B)Cells formed clusters,or foci,after infection.
C)The cells seemed to demonstrate uninhibited proliferation.
D)The cells exhibited flattened morphology.
E)The cells exhibited metabolic properties similar to those observed in tumor cells.