chapter 3

Question 1

semiconservative replication

Answer 1

each parental strand is a template, new molecules have one old and one new.

Question 2

conservative replication

Answer 2

original model serves as a template only, no intermediate DNA.

Question 3

dispersive replication

Answer 3

DNA fragments are templates old and new pieces are formed into molecules.

Question 4

meselson-stahl experiment

Answer 4

-overview: e.coli grown in N15 (heavy), then transferred to N14
-semiconservative: DNA in 1st gen are intermediate and 2nd gen were two discrete bond
-conservative result: no intermediate DNA, one band of N15-N15 and another of N14-N14
-dispersive result: 1st gen intermediate with the single intermediate band becoming lighter

Question 5

ORC

Answer 5

origin of recognition complex, protein
-made in G1 phase, binds to ARS sequence
-in G1 phase going to S
-DNA-A, helicase

Question 6

DNA-A

Answer 6

part of ORC: protein, binds to DNA
-forms kink by breaking H bonds
-allows helicase to enter

Question 7

helicase

Answer 7

part of ORC, separates DNA by breaking H bonds, energy from hydrolysis of ATP

Question 8

ARS

Answer 8

autonomously replicating region
-100 bp regions that are replicated often over the genome.

Question 9

single stranded binding proteins

Answer 9

bind to each single-stranded DNA, stabilizing and preventing them from reforming a double-stranded DNA by complementary base pairing.

Question 10

enzyme: DNA Polymerase

Answer 10

adds nucleotides 5’-3’. 12 types

Question 11

primase: RNA Polymerase

Answer 11

only sticks to single-stranded DNA, doesn’t stick to double-stranded DNA.

Question 12

lagging strand moves ______ from replication fork

Answer 12

away

Question 13

okazaki fragments

Answer 13

fragments of discontinuous replication

Question 14

DNA ligase

Answer 14

seals nick between gaps, forms a P bond and OH

Question 15

what is the problem with DNA after replication?

Answer 15

can’t degrade gene coding regions, leaves single strand hanging

Question 16

telomeres

Answer 16

protect ends of chromosomes: TTAGGG, repeats about 200 times

Question 17

telomerase

Answer 17

protein enzyme that carries RNA fragments, matches telomere
-needed for stem cells
-replicate and need more
-if a normal cell turns on gene for telomerase= creates cancerous

Question 18

senescence:

Answer 18

non-dividing
-aging process includes cells that do not replicate
-avoids cancer

Question 19

describe the big picture between cells and telomeres

Answer 19

-most cells do not lengthen
-they allow themselves and telomere to shorten
-once they shorten too much proteins cant stick and sends sends a cell signal for senescence
-as telomers shorten, cells accumulate=possible mutations

Question 20

DNA replication is

Answer 20

semidiscontinious

Question 21

DNA Pol 1:

Answer 21

removes primers on okazaki fragments and replaces it with DNA

Question 22

DNA ligase

Answer 22

seals nicks between gaps after DNA poly 1 removes primers. P bond and OH

Question 23

telomeres

Answer 23

protect the ends of chromosomes: TTAGGG
repeated about 200 times.

Question 24

telomerase

Answer 24

protein enzyme that carries RNA fragment that matches telomere.
-once its longer, primer comes in , DNA polymerase adds and makes a new strand, ligase seals.
-needed for stem cells.