MG Ch. 24

Question 1

How do we know that cancer development requires more than one mutation?

Answer 1

The progressive, time- and age-dependent development of tumorigenesis, coupled with a relatively low cancer rate compared to the mutation rate, argue for a multistep mutational model for cancer.

Question 2

There is much _____ DNA methylation in cancer cells than in normal cells.

Answer 2

less

Question 3

In cancer cells promoters of some genes are

Answer 3

hypermethylated

Question 4

What are the major regulatory points in the cell cycle?

Answer 4

late G1 phase (G1/S checkpoint)
late G2 phase (G2/M checkpoint)
M phase (M checkpoint)

Question 5

Given that TP53 is a recessive gene and is not located on the X chromosome, why would people who inherit just one mutant copy of a recessive tumor-suppressor gene be at higher risk of developing cancer than those without the recessive gene?

Answer 5

Individuals with two copies of the gene would need to experience separate mutations in both copies to develop cancer, whereas individuals with one functional copy would only need a single mutation.

Question 6

What happens in cases where the ras gene is mutated?

Answer 6

It continually signals cell division.

Question 7

Distinguish between oncogenes and proto-oncogenes.

Answer 7

Oncogenes are genes that induce or maintain uncontrolled cellular proliferation associated with cancer. They are mutant forms of proto-oncogenes, which normally function to regulate cell division.

Question 8

______ mutations are those that confer a growth advantage to a cancer cell.

Answer 8

Driver

Question 9

_________ mutations increase in cancer cells over time, possibly due to the genomic instability of cancer cells.

Answer 9

Passenger

Question 10

How might hypermethylation of the TP53 gene promoter influence tumorigenesis?

Answer 10

The concentration of p53 will be decreased, the process of tumorigenesis will be stimulated.

Question 11

How can mutations in noncoding segments of DNA contribute to the development of cancers?

Answer 11

Mutations in noncoding regulatory sequences (such as promoters, enhancers, and transcription binding sites) of genes such as proto-oncogenes, tumor-suppressor genes, or cell cycle genes could alter the timing or level of their expression leading to cancer.

Question 12

Any agent that causes damage to DNA is a potential ____

Answer 12

carcinogen