1B

Question 1

nucleotide vs nucleoside

Answer 1

nucleoTide = base + sugar + phosphate
nucleoside = base + sugar

Question 2

dna backbone is made of

Answer 2

pentose sugar and phosphate group

Question 3

what are the pyrimidines? purines?

Answer 3

purine s= Adenine, thymine (1 ring)

pyrimidine = Cytosine, Uracil, Threonine (2 rings)

Question 4

how many hydrogen bonds between AT? GC

Answer 4

2 in AT

3 in GC

Question 5

which is stronger? GC or AT

Answer 5

GC

Question 6

define:
denaturation
reannealing
hybridization

Answer 6

denature - unwinds the 2 strands (ex. high temp)
reanneal - puts them back together
hybridizayion - a single strand will readily bind another single strand

Question 7

Dna gyrase is what class of topoisomerase? what does it do?

Answer 7

class 2 topoisomerase
uncolis DNA AHEAD of replication fork

Question 8

helicase

Answer 8

unwinds dna AT replication fork i.e. separates DNA

Question 9

Single-strand binding protein (SSB)

Answer 9

keeps DNA unwound by stopping reannealing

Question 10

SSBs stabilize ssDNA by

Answer 10

binding to it

Question 11

all biological dna synthesis occurs from what end to what end

Answer 11

5’ to 3’

Question 12

primase

Answer 12

lays down short RNA primer on unwound DNA

-the RNA primer is complimentary to DNA

Question 13

dna polymerase

Answer 13

makes DNA that’s complimentary to unwound dna

Question 14

synthesis that proceeds in direction of replication fork

Answer 14

leading strand

Question 15

synthesis that proceeds in opposite direction of replication fork

Answer 15

lagging strand

Question 16

which strand, leading or lagging, has okazaki fragments

Answer 16

lagging

Question 17

what stitches okazaki fragments together

Answer 17

dna ligase

Question 18

T/F: DNA synthesis is unidirectional

Answer 18

false - bidirectional, 2 replication forks form and work in opposite directions

Question 19

______ has proofreading activity that corrects mistakes

Answer 19

dna polymerase

Question 20

which DNA polymerase removes RNA primers

Answer 20

DNA polymerase 1

Question 21

how many times does replication happen in a cell generation? during what phase(s)

Answer 21

once

S phase

Question 22

is dna replication conservative, semi-conservative, or dispersive

Answer 22

semi-conservation bc there’s intermediate weights

Question 23

telomerase

Answer 23

catalyzes lengthening of telomeres

has molc of RNA that serves as a template for new telomere segments

Question 24

nuclease

Answer 24

cuts out unwanted or defective segments of nucleotides in DNA sequence

Question 25

enzyme that relieves the winding strain generated during unwinding of double helix by creating a single strand nick in the DNA

Answer 25

topoisomerase

Question 26

holds the replication fork of dna open so it can get ready for synthesis

Answer 26

single strand binding protein

Question 27

Prokaryotes or eukaryotes: | has multiple origins of replication

Answer 27

eukaryotes have multiple origins | prokaryotes have a single origin for their circular dna

Question 28

what enzyme has 3' to 5' exonuclease activity

Answer 28

DNA polymerase with it's proofreading activity bc it will backup and replace the incorrect nucleotide with the right one

Question 29

mismatch repair

Answer 29

enzyme recognizes incorrect pairing and cuts out the dna with the mismatch --> polymerase readds the right nucleotides

Question 30

how do repair enzumes during mismatch repair know which strand of DNA to cut

Answer 30

it cuts the DNA strand that does NOT have methylations bc it takes some type after replication for new strands to have methylation

Question 31

damaged base gets cut out --> base's sugar-phosphate backbone gets cut out --> more nucleotides next to base get cut out --> polymerase remakes the cut-out nucleotides

Answer 31

base-excision repair

Question 32

nucleotide-excision repair

Answer 32

damaged nucleotide gets cut out then polymerase replaces it

Question 33

nick translation

Answer 33

polymerase chews off bad nucleotides and replaces them with new nucleotides -I'm confused about difference to nucleotide exciison repair

Question 34

SOS response in E Coli when there's too much DNA damage

Answer 34

polymerase replicates over the damaged DNA like it's normal by using damaged dna as template

Question 35

caps on the ends of chromatids which protects DNA from deterioration

Answer 35

telomeres

Question 36

which strand of dna is synthesized in a discontinuous fashion

Answer 36

lagging strand

Question 37

pieces of newly synthesized dna on the lagging strand

Answer 37

okazaki fragments

Question 38

when is genetic material lost from telomeres

Answer 38

during the joining of okazaki fragments

Question 39

(EUk or Prokaryotes) have 60S and 40S ribosome subunit | (EUk or Prokaryotes) have 50S and 30S ribosome subunit

Answer 39

Euk - 60, 40 | Pro- 50, 30

Question 40

noncoding region of dna ____ | coding region of dna ___

Answer 40

``` noncoding = intron coding = exon ```

Question 41

reverse transcriptase

Answer 41

catalyzes the synthesis of DNA from RNA

Question 42

dna synthesis from polymerase and reverse transcriptase are in what direction

Answer 42

5' to 3' bc all dna synthesis is through this way

Question 43

what strcture: 1. site of cellular respiration 2. cell trashcans 3. site of translation from mRNA to protein 4. involves glycosylation

Answer 43

1. mitochondria 2. lysosomes 3. ribosomes 4. golgi apparatus

Question 44

cleave specific sequences of DNA

Answer 44

endonuclease

Question 45

how many codons? how many AAs?

Answer 45

64 codons 21 Amino acids so many diff codons may code for the same AA

Question 46

where does translation occur

Answer 46

ribosomes

Question 47

where does transcription occur

Answer 47

nucleus

Question 48

where are ribosomes abundant?

Answer 48

cytosol & rough endoplasmic reticulum

Question 49

tRNA binds to ____ to be used in ____

Answer 49

ribosomes to be used in translation

Question 50

translation occurs within the

Answer 50

cytosol

Question 51

amino acids are linked by what bonds

Answer 51

peptide bonds

Question 52

Covalently linked nucleotides constitute the ______ bonds in DNA.

Answer 52

phosphodiester