B/11

Question 1

What is the role of the telomeres?

Answer 1

to protect the chromosomes, they get used up each cycle

Question 2

Which normal cells have telomerase enzyme?

Answer 2

germ cells have it

Question 3

What can happen to the telomeres / telomerases in neoplastic tissue?

Answer 3

• can lose all telomeres with free DNA edges

- can regain telomerase activity and have unlimited division

Question 4

What are cytogenic aberrations?

Answer 4

Genetic changes that are large enough to be seen in karyotypes

Question 5

Most common structural abnormalities (4) [telomeres]

Answer 5

• Balanced translocations
• Deletions
• Aneuploidy
• Gene amplification

Question 6

Example of tumor caused by balanced translocation?

Answer 6

Ewing’s sarcoma

Question 7

What is Ewing’s sarcoma a result of?

Answer 7

Fusion between chromosome 11 (FLI1 gene) and chromosome 22 (EWS gene).

Question 8

2 patterns of gene amplification

Answer 8

• double minute chromosomes

- homogenously staining regions

Question 9

What happens when there are short telomeres?

Answer 9

they are recognized by DNA repair systems and cause cell cycle arrest via p53 and RB

Question 10

How are telomeres replenished?

Answer 10

by telomerase reverse transcriptase

Question 11

How do neoplastic cells avoid massive mitotic catastrophe to continue growing?

Answer 11

by reactivating the telomerase enzyme and stopping the BFB cycle