Kandpal- Replication and Telomeres

Question 1

what is the difference in number of replication origins between bacteria and mamallian cells?

Answer 1

bacteria have a single origin of replication and mammalian cells have multiple origins of replication

Question 2

which ploymerase is has primase activity?

Answer 2

alpha polymerase

Question 3

which polymerase has repair activity?

Answer 3

beta polymerase

Question 4

which polymerase is used for mitochondrial replication?

Answer 4

gamma polymerase

Question 5

which polymersae is needed for nuclear replication?

Answer 5

delta polymerase and gamma polymerase

Question 6

are okazaki fragments bigger in mammalian cells than they are in bacteria cells?

Answer 6

no. they are smaller (0.1-0.2 Kb) and bacteria are bigger (1.0-2.0 Kb)

Question 7

what is RNaseH needed for?

Answer 7

to degrade the RNA part of the RNA-DNA hybrid

Question 8

what is the shape of a bacteria (e.Coli) genome and the shape of a mammalian genome?

Answer 8

bacteria is circular and mammalian is linear

Question 9

at the end of replication, what happens after the RNA primer is removed from the 5’ end?

Answer 9

it is not filled up, because there is no polymerase availabe with 3’–> 5’ activity

Question 10

what eventually happens to the 5’ end?

Answer 10

they will continue to shorten after each replication cycle which can lead to consequences like eventual coding loss

Question 11

what do chromosome replication and stable propagation require?

Answer 11

origins of replication

Question 12

what helps to attach chromosomes to the nuclear envelope?

Answer 12

telomeres

Question 13

why is it important that telomeres help to seal the ends of chromosomes?

Answer 13

to avoid undesirable fusion an avoid aberrant recombination

Question 14

what kind of repeats do telomeres have and how are they synthesized?

Answer 14

hexameric repeats that are synthesized by telomerase

Question 15

what makes up a telomerase?

Answer 15

Ribonucleoprotein (protein+RNA)

Question 16

what subunit of telomerase is responsible for reverse transcriptase activity?

Answer 16

Protein subunit

Question 17

which subunit of the telomerase helps to serve as a template?

Answer 17

RNA (150 nucleotide long)

Question 18

what does C-A strand degradation in telomeres lead too?

Answer 18

generation of G-tail

Question 19

what is the proposed model that describes how telomeres protect chromosome ends?

Answer 19

G-quadruplex or G-Quartet Structure.

4 G bases on the same strand stack-up by base pairing

Question 20

what type of cells in humans are known to have telomerase activity?

Answer 20

germ cells, isolated fibroblasts (mainly in elderly individuals)

Question 21

telomeres are referred to as the mitotic clock. why?

Answer 21

because the shorter they become in length, the more likely replicative senescense or apoptosis will occur

Question 22

how does telomerase activity relate to human cancer?

Answer 22

normal tissues will not have telomerase (except germ cell) but tumors have telomerase activity

Question 23

what would a scientist target in order to intervene in antitumor activity?

Answer 23

telomerase activity and telomere structure

Question 24

what is the function of the telomerase inhibitor GRN163L (oligonucleotide)?

Answer 24

it is a competitive inhibitor that binds to the active site of the enzyme (13-mer oligonucleotide)

Question 25

what are the effects of the G-qudruplex stabilizing agent RHPS4 (G-quadruplex ligand)?

Answer 25

stabilizes G-quadruplex and prevents attachment of telomerase.

Question 26

what is pentacylic acridinium methosulfate?

Answer 26

RHPS4 (G-quadruplex ligand)

Question 27

what is considered to be an obligatory intracellular parasite?

Answer 27

virus (completely dependent on host)

Question 28

what is the name for an inert virus and what is the outer protective layer called?

Answer 28

virion. the nucleic acid is wrapped in a capsid

Question 29

can viruses have envelopes?

Answer 29

technically yes, if they acquire them from the host cell membrane

Question 30

is virus DNA single or double stranded?

Answer 30

both

Question 31

is virus RNA single of double stranded?

Answer 31

both

Question 32

how are viral nucleic acids replicated?

Answer 32

only replicated in host cells using host cell machinery

Question 33

how does a viral genome replicate?

Answer 33

requires reverse transcriptase so that RNA can be converted to DNA for replication

Question 34

why do viruses require integrase enzyme?

Answer 34

in order for cDNA to be integrated into the host genome

Question 35

how does reverse transcription work during HIV replication?

Answer 35

utilizes lysyl tRNA as a template

Question 36

what would be a target to inhibit HIV replication?

Answer 36

replication integrase protease

Question 37

what is targeted to prevent HIV infection?

Answer 37

fusion, reverse transcriptase, pretease and integrase

Question 38

what is a common nucleotide analogue drug that is used for treatment of HIV?

Answer 38

zidovudine (ZDV, AZT) which is an analouge of deoxythymidine

Question 39

how does zidovudine work?

Answer 39

prevents DNA chain elongation by reverse transcriptase (absence of 3’ OH)

Question 40

antibiotics use inhibitors of what enzyme to prevent DNA replication?

Answer 40

inhibitors of bacterial gyrase

Question 41

chemotherapy uses inhibitors of what enzyme to prevent DNA replication?

Answer 41

inhibitor of human topoisomerases

Question 42

what 4 things would you want to inhibit the synthesis of in order to limit the supply of substrates?

Answer 42

dATP, dCTP, dGTP, dTTP

Question 43

what is the role of 5-Fluorouracil in cancer chemotherapy?

Answer 43

inhibits DNA synthesis by inhibiting thymidylate synthase (an enzyme for TMP synthesis)

Question 44

what drug is enzymatically converted to fluorouracil in the body if it is orally-adminstered?

Answer 44

capecitabine (Xeloda)