Chpt 28b

Question 1

Semiconservative synthesis

Answer 1

each parental strand serves as template for synthesis of a new complementary strand

Question 2

DNA synthesis: Leading and Lagging strand

Answer 2

DNA is synthesize in the 5’ to 3’ direction

Leading strand- continuous synthesis
-goes into the replication fork

Lagging strand- discontinuous synthesis
-results in Okazaki fragments

Question 3

DNA ligaase

Answer 3

Seals nicks

• synthesizes phosphodiester bond between the 3’ hydroxyl group at the end of one change and the 5’ phosphate group at the of the other strand of the dsDNA
• requires ATP for archaea and eukarya
• requires NAD+ for bacteria

Question 4

Process of initiation of replication

Answer 4

1) DnaA protein binds
2) ssDNA exposed to prepriming complex
- helicase, SSB, Primase
3) Polymerase homoenzyme assembles

Question 5

Trombone model of lagging strand synthesis

Answer 5

DNA poly III synthesizes about 1000 nucleotides per okazaki fragment
-as nucleotides are added the slide lengthens

Question 6

Telomerase

Answer 6

Specialized eukaryotic reverse transcriptase

• synthesizes the linear ends of chromosomes (telomere)
• carries own RNA template

Question 7

Telomere

Answer 7

Linear ends of chromosomes

• Humans have repeated seq AGGTTT repeat
• protect ends from nuclease digestion
• senesence aging

Question 8

In vivo telomere structure

Answer 8

ss region of DNA invades and H bonds to telomere repeat sequence
-stabilized by telomere binding proteins

Question 9

Telomerase Model

Answer 9

Elizabeth blackburn and Carol Greidor model

• Elongation
• Translocation

Question 10

Reverse transcriptase

Answer 10

Retrovirus- Human immunodeficiency virus (HIV)

-RNA genome converts RNA into viral DNA which integrate into human genome

Question 11

Reverse transcriptase inhibitors

Answer 11

Nucleoside analogues-chain terminators
-Zidovudine (AZT)
-2',3' dideoxyinosine (ddI) *didanosine
Nonnucleotide analgoues
Protease Inhbiitors

Question 12

DNA repair

Answer 12

repair is done due to damage that occurs from various sources