Lecture 7b

Question 0

When do somatic cells stop losing telomere length?

Answer 0

Senescence

Question 1

What protein complex protects telomeres from damage?

Answer 1

Shelterin

Question 2

How can oncogenically active cells bypass senescence?

Answer 2

Loss of p53 check point

Question 3

How is the telomere lasso formed?

Answer 3

Annealing the the G-rich strand to the small region of C-rich strand

Question 4

Where is telomerase constitutively expressed?

Answer 4

Germ line cells

Question 5

Oncogenically transformed cells that have bypassed the p53 checkpoint can survive crisis if they express what?

Answer 5

Telomerase

Question 6

What percentage of cancer cells express telomerase?

Answer 6

85%

Question 7

How does telomerase help cancer cells surpass the Hayflick Limit and achieve biological immortality?

Answer 7

Increased telomerase activity allows for indefinite proliferation

Question 8

After how many divisions do normal cells enter crisis?

Answer 8

About 20

Question 9

Why does lagging strand synthesis stall at chromosome ends?

Answer 9

No place to lay down a new RNA primer

Question 10

What kind of enzyme is telomerase?

Answer 10

Reverse transcriptase

Question 11

What does telomerase add, and to which end of which strand?

Answer 11

Telomere repeats to the 3’ end of the lagging strand

Question 12

What are the two essential subunits of telomerase?

Answer 12

hTR and hTERT

Question 14

What does hTERT stand for?

Answer 14

Human telomerase reverse transcriptase

Question 15

What is hTERT composed of?

Answer 15

The protein catalytic subunit

Question 16

What does hTR stand for?

Answer 16

Human telomerase RNA

Question 17

Where does hTERT bind on the DNA?

Answer 17

3’ end of G-rich strand overhang

Question 18

What is hTR?

Answer 18

The RNA template for telomerase

Question 19

What protein regulates telomerase?

Answer 19

Shelterin

Question 20

What do long telomeres form?

Answer 20

Closed loop that inhibits telomerase activity and DNA repair

Question 21

What do short telomeres form?

Answer 21

Open formation that induces telomerase or p53 depending on cell

Question 22

In addition to protecting the ends of chromosomes, what other function do telomeres perform?

Answer 22

Act as a sensor to overall DNA damage in a cell

Question 23

How do the 15% of cancers that don’t express telomerase achieve immortality?

Answer 23

Via Alternative Lengthening of Telomeres (ALT)

Question 24

Which proteins can alternatively lengthen telomeres?

Answer 24

RAD 51-52

Question 25

Increasingly unstable genomes within a tumor leads to what?

Answer 25

Intratumor heterogeneity

Question 26

Where are telomeres the longest?

Answer 26

Muscle, brain, and gametes

Question 27

Where are telomeres shorter?

Answer 27

Stomach, blood cells, liver, and kidney

Question 28

Mutations in the protein or RNA components of telomerase can cause what disease?

Answer 28

Dyskeratosis Congenital (DKC)

Question 29

In what age does DKC develop, and what do its symptoms resemble?

Answer 29

5-15 year olds, resembles premature aging

Question 30

What is the function of GRN163L?

Answer 30

Inhibits telomerase growth, telomere synthesis, and cell growth

Question 31

What is glycosylation?

Answer 31

Normal enzymatic process in which sugars are added to proteins or lipids

Question 32

What is glycation?

Answer 32

Non-enzymatic attachment of sugars to proteins or lipids

Question 33

What causes glycation?

Answer 33

High blood glucose levels

Question 34

What are advanced glycation end products (AGEP) associated with?

Answer 34

Premature and excess wrinkling and aging; damage to blood vessels, skin, kidneys, brain

Question 35

hTERT extends the G-rich strand by how many nucleotides?

Answer 35

6