Telomeres and Telomerases

Question 1

Telomeres

Answer 1

repeat sequences (6-16 bp long) that are important for stabilizing the ends of linear chromosomes; eukaryotic chromosomes have 3’ overhangs after replication because ends of lagging strands can not be fully copies

Question 2

End replication problem

Answer 2

telomeres are shorted on both daughter strands after each round of DNA replication; there are 3’ overhangs on daughter strands because there is no primer for DNA pol to fill in the gap

Question 3

Cell senescence

Answer 3

cells stop dividing and die when telomeres get too short; naturally occurring in all tissues and organs

Question 4

Stem cells

Answer 4

Use telomerase to prevent telomere shortening/cell senescence; immortal

Question 5

Telomerase

Answer 5

Extends 3’ overhang by synthesizing additional repeats by using RNA as a template; composed of telomerase RNA and telomerase reverse transcriptase

Question 6

Steps to lengthen telomeres after DNA replication

Answer 6

1) telomerase extends 3’ overhang using telomerase RNA as template
2) Primase makes new RNA primer on DNA made by telomerase
3) DNA pol makes new DNA strand