chapter 7

Question 1

3 key properties of genetic material

Answer 1

• information content (encode proteins and DNA)
• faithful replication
• infrequent mutations

Question 2

when watson and crick collabed they found out

Answer 2

• genes encode specific traits and proteins
• genes are carried on chromosome
• DNA is the genetic material

Question 3

griffith experiment

Answer 3

experimented with mice, DNA is the transforming principle

Question 4

avery, macleod, mccarty

Answer 4

more dead mice, but used enzymes to break down other things like lipids and polysachs to make SURE dna was that girl

Question 5

hershey-chase

Answer 5

T2 phage injects bad DNA (not proteins as originally thought) into victim (e.coli) so it reproduces it.

Question 6

4 nucleotides

Answer 6

A, T, G, C or in fancy words dAMP, dTMP, dGMP, dCMP

Question 7

chagraffs rule

Answer 7

total pyrimidines = total purines

Question 8

pyrimidine bases are

Answer 8

T and C

Question 9

purine bases are

Answer 9

A and G

Question 10

what is the visual difference between pyrimidines and purines

Answer 10

pyrimidine is single ring and purine is double ring

Question 11

What are the nucleotide pairs

Answer 11

AT
GC

Question 12

double helix structure

Answer 12

looks like spiral staircase, each strand is a nucleotide chain held together by sugar phosphate backbone

Question 13

phosphodiester bonds

Answer 13

bridge between 2 oxygens and 2 adjacent sugar residues
5’ to 3’

Question 14

polarity

Answer 14

strands are assembled in a directional manner (5’ to 3’)

Question 15

how many hydrogen bonds hold together A and T

Answer 15

2

Question 16

how many hydrogen bonds hold together G and C

Answer 16

3

Question 17

semiconservative

Answer 17

one old strand (template) and one new strand

Question 18

other options (conservative and dispersive)

Answer 18

conservative: olds together and news together
dispersive: chunks are swapped

Question 19

DNA strands bind where they are ______

Answer 19

isodense (have similar density)

Question 20

DNA polymerase III

Answer 20

synthesizes DNA (only in 5’ to 3’ direction)

Question 21

DNA polymerase III can only add nucleotides to the ___ end of the existing strand

Answer 21

3’

Question 22

leading strand

Answer 22

synthesized continuously (end is 3’ so it can just go down the line)

Question 23

lagging strand

Answer 23

synthesized discontinuously (end is 5’ so it has to do it in chunks using RNA primers)

Question 24

primase

Answer 24

synthesizes RNA primers so DNA polymerase III has somewhere to attach

Question 25

where are RNA primers?

Answer 25

along the lagging strand and at the beginning of the leading strand

Question 26

polymerase I

Answer 26

degrades RNA primer and fills gaps (okazaki fragments) with DNA

Question 27

what direction does polymerase I add nucleotides in

Answer 27

5' to 3' direction

Question 28

ligase

Answer 28

repairs the nick and seals the strand

Question 29

replisome

Answer 29

complex of proteins for DNA replication

Question 30

helicases

Answer 30

melt duplex (breaks hydrogen bonds to split the strand)

Question 31

single strand binding proteins

Answer 31

prevent reformation of duplex

Question 32

topoisomerase

Answer 32

relax supercoiling

Question 33

proofreading

Answer 33

polymerase I and III use 3' to 5' exonuclease activity to excise mismatches base pairs

Question 34

origin of replication

Answer 34

fixed place where replication starts (common in e.coli, replication then branches out in both directions)

Question 35

replication bubble

Answer 35

chunk that is being replicated (where template is unwound and strands are apart)

Question 36

replication fork

Answer 36

where DNA is unwound

Question 37

telomeres

Answer 37

repetitive buffer at the end of DNA strand (100s of nonsense nucleotides so info isn't lost)

Question 38

telomorase

Answer 38

ribonucleoprotein that puts telomeres

Question 39

elongation

Answer 39

extends the 3' end with telomeres after each replication

Question 40

translocation

Answer 40

shifts telomere down