DNA 2

Question 1

Specialized nucleotide sequences at ends of eukaryotic chromosomes

Answer 1

telomeres

Question 2

What is the end replication problem

Answer 2

Lagging strand template (3’ end) cannot be replicated in linear chromosomes
shortens it

Question 3

shelterin

Answer 3

Covered by proteins forming protective chromosome cap on telomere

Question 4

What does Telomerase

Answer 4

Recognizes telomere sequence and elongates it in 5’ → 3’ direction

Question 5

Replicative cell senescence

Answer 5

Phenomenon observed in cell cultures in which cell proliferation slows down and finally irreversibly stops

Question 6

Telomerase activity decreases as you age causing

Answer 6

Replicative cell senescence

Question 7

7 proteins involved in DNA replication

Answer 7

DNA polymerase III
DNA polymerase I
Primase
Helicase
DNA ligase
Topoisomerases (i.e., DNA gyrase)
Telomerase

Question 8

DNA polymerase III does what

Answer 8

Adds nt

is a complex of 10 proteins

Question 9

DNA polymerase I does what

Answer 9

Removes RNA primer; adds nt

Question 10

Primase does what

Answer 10

Adds RNA primer

Question 11

Helicase

Answer 11

Unwinds DNA

Question 12

DNA ligase

Answer 12

Joins DNA fragments
functions on both lagging strand (most active)
and leading strand (1 spot in ori)

Question 13

Topoisomerases (i.e., DNA gyrase)

Answer 13

Adds & removes supercoils

Question 14

Telomerase

Answer 14

Adds telomeres in eukaryotes

Question 15

Single-strand binding proteins

Answer 15

Stabilize ssDNA

Question 16

Origin binding protein (DnaA)

Answer 16

Opens origin of replication

initiates DNA replication

Question 17

3 types of telomerases

Answer 17

DNA gyrase, topoisomerase I, topoisomerase IV

Question 18

What is the general process involved in DNA replication?

Answer 18

Semiconservative replication
Use “old” strand as template for “new” strand
Resulting DNA contains ½ “old” and ½ “new” DNA

Question 19

what enzymes/proteins are involved in DNA replication?

Answer 19

DNA polymerase (I, III), including DNA primase,
DNA helicase,
DNA ligase,
topoisomerase.

Question 20

What is the general process of transcription?

Answer 20

Synthesis of mRNA from DNA template from

• DNA template (single strand)
• RNA polymerase
• Ribonucleoside triphosphates (A,G,C,U)

Question 21

What are some differences between prokaryotic and eukaryotic transcription?

Answer 21

Prokaryotic-RNAs are released/processed in cytoplasm
1 RNA polymerase
transcription/translation occurs simultaneously

Eukaryotic-RNAs are released/processed in the nucleus
3 RNA polymerase
transcription in nucleus then translation occurs separately in cytoplasm

Question 22

prokaryotic transcription?

Answer 22

RNAs are released/processed in cytoplasm
1 RNA polymerase
transcription/translation occurs simultaneously

Question 23

eukaryotic transcription?

Answer 23

RNAs are released/processed in the nucleus
3 RNA polymerase
transcription in nucleus then translation occurs separately in cytoplasm

Question 24

What are sigma factors?

Answer 24

• released after RNA polymerase binds promoter
• subunits of all bacterial RNA polymerases
• direct transcription initiation

Question 25

What are transcription factors,

Answer 25

- Eukarya and Archaea - Not part of RNA polymerase - Bind to promoter - proteins that transcribe DNA to RNA

Question 26

What are promoters?

Answer 26

- sequence of DNA needed to turn a gene on or off - initiates transcription - Recognized by a factor (Bacteria) or transcription factors (Archaea and Eukarya)