week 8

Question 1

Nitrogenous base linked by

Answer 1

phosphodiester bond

Question 2

GC forms __ H bonds -Slightly ___ base pairing

AT forms __ H bonds

Answer 2

3
stronger
2

Question 3

Always read nucleotides

Answer 3

from 5’ to 3’

Question 4

minor grooves are ___ together

Major grooves ___ apart -Enough space for a ___ to get access to ___

Answer 4

minor grooves are closer together
Major grooves further apart
Enough space for a protein to get access to nucleotide

Question 5

most bacterial chromosomes are

Answer 5

circular

Question 6

Bacteria doesn’t have ____ to wrap dna, uses ____ instead

Answer 6

Bacteria doesn’t have histones to wrap dna, uses supercoiling instead

Question 7

DNA gyrase (2)

Answer 7

topoisomerase

makes supercoiled DNA

Question 8

supercoiling needs what and why

Answer 8

Requires E from atp

Makes it essentially impossible to pull apart

Question 9

In most bacteria DNA is _____ supercoiled

Coiled to the ____ direction of helical shape

Answer 9

In most bacteria DNA is negatively supercoiled (under-wound)

Coiled to the opposite direction of helical shape

Question 10

Back reaction

does it need E

Answer 10

releases supercoiled (requires no extra E)

Question 11

each strand serves as a ____ for the new daughter strand
Each strand is the reverse ____ of the other
____ replication

Answer 11

each strand serves as a template for the new daughter strand
Each strand is the reverse complement of the other
Semiconservative replication

Question 12

DNA polymerase

Answer 12

catalyze synthesis of complementary strand of DNA

Question 13

dna synthesized in what direction and forms what bonds

Answer 13

Synthesized in 5’-3’ direction only forming phosphodiester bonds

Question 14

Enzymes require (3)

Answer 14

Template - direct synthesis of complementary strand
Primer. DNA or RNA
dNTP (dATP, dTTP, dCTP, dGTP) - deoxynucleotide triphosphates

Question 15

Why does DNA polymerase need a primer

Answer 15

Can elongate nucleic acid but not form it from nowhere

Question 16

Replication fork

____ replication from single ori

Answer 16

is where DNA is unwound and strands are separated

Bidirectional replication from single ori

Question 17

DnaA binds to ___

causes what?

Answer 17

bind to oriC (origin of repl) causing bending and separation of strands

Question 18

DnaB does what?

does it need E

Answer 18

helicases like DnaB separate strands
Form the replication fork
Requires atp

Question 19

Single stranded binding proteins bind

Answer 19

ssDNA to prevent strands from annealing/coming together

Question 20

primase synthesizes

Answer 20

RNA primer

Question 21

Lagging and leading strand is synthesized by

Answer 21

DNA polymerase III

Question 22

Okazaki fragments

does it need new primers for every sequence

Answer 22

are short pieces of DNA synthesizes on the lagging strand

yes

Question 23

e.coli has how many polymerase

which one plays more role in rep

Answer 23

e.coli has 5 DNA polymerase with polymerase III playing the major role in replication

Question 24

DNA polymerase holoenzyme

Answer 24

complex of 10 proteins

Contains proofreading function

Question 25

dnaQ (3)

Answer 25

proofreading

subunit of DNA polymerase III

Removal of mismatched base from 3’ end of growing strand by exonuclease activity of enzyme

Question 26

is proofreading 100% effective?

Answer 26

Activity isn’t 100% effective
Mutation rates are 10^-8 to 10^-11
Depends on rate of cell replication or type of cell

Question 27

one reason why mutations occur

Answer 27

nucleotides have other/rare forms

Question 28

DNA polymerase I

Answer 28

removes RNA primers, fill gaps with DNA

Question 29

Okazaki fragments are joined by

Answer 29

DNA ligase

Question 30

dna ligase forms a _____ bond between 3’-___ of the ____ strand with the 5’-____ of an Okazaki fragment

Answer 30

dna ligase forms a phosphodiester bond between 3’-OH of the growing strand with the 5’-phosphate of an Okazaki fragment

Question 31

____ proteins binds ___ sequence and prevents further replication

Answer 31

tus proteins binds ter sequence and prevents further replication

Question 32

Topoisomerases

Answer 32

liberate chromosomes

Cleave DNA, thread strand through, relegate DNA