Exam 2 Chapter 7

Question 1

Double helix held together by:

Answer 1

Phosphodiester bond

Question 2

Proteins break open helix for synthesis:

Answer 2

Replication fork

Question 3

• 2 strands in double helix run in opposite direction

- Double helix held together by noncovalent interactions

Answer 3

Antiparallel

Question 4

• Hydrogen bonds

- Hydrophobic interactions

Answer 4

Non-covalent interactions

Question 5

Phosphodiester bond

Answer 5

• Links nucleotide bases together

- Hydroxyl group on 1 base binds w/ phosphate on adjacent base

Question 6

Semidiscontinuous process

Answer 6

• New DNA always synthesized in 5’—3’

- Parental strand read 3’—5’

Question 7

Leading strand of the Semidiscontinuous process

Answer 7

Continuously synthesized from 5’—3’

Question 8

Lagging strand of the Semidiscontinuous process

Answer 8

Synthesized from 5’—3’ but discontinuous = okazaki fragments

Question 9

Each daughter cell contains 1 parent strand + 1 new strand

Answer 9

Semiconservative

Question 10

• starts at several points

- Replication ‘bubble’ is formed

Answer 10

Bidirectional w/ multiple origins

Question 11

DNA helicases

Answer 11

• Unwind parental DNA double helix

- Require ATP to form the replication fork

Question 12

• Begin RNA synthesis for ‘priming’ DNA synthesis

Answer 12

DNA primases

Question 13

Single-stranded DNA binding proteins

Answer 13

Prevents premature binding & winding of DNA

Question 14

DNA ligase

Answer 14

• JOins nucleotides in fragments by forming phosphodiester bonds
• Requires ATP

Question 15

Facilitates unwinding of double helix during replication & transcription to release torsional stress

Answer 15

Topoisomerases

Question 16

Topoisomerases 1

Answer 16

breaks 1 DNA strand & then rejoins

Question 17

Topoisomerases 2

Answer 17

Breaks both strand & the rejoins

Question 18

• Internal, spontaneous

- due to errors in DNA replication

Answer 18

Endogenous mutations

Question 19

Exogenous mutations

Answer 19

• Environmental

- ionizing raditation, polyaromatic hydrocarbons, nitrosamines, free radicals, chemotherapy

Question 20

• Most common genetic variation
• Commonly found in DNA b/t genes
• Can influence disease

Answer 20

Single Nucleotide Polymorphisms

Question 21

Removes mutations formed by UVlight & environmental chemicals

Answer 21

Nucleotide excision repair