DNA Replication

Question 0

endonuclease

Answer 0

nucleases that cleave the nucleotide chain at positions in the interior of the chain

Question 1

What are the properties of DNA?

Answer 1

3’-5’ phosphodiester bonds
double stranded
double helix

Question 2

exonuclease

Answer 2

Cleave the chain by removing individual nucleotides from one of the two ends

Question 3

semiconservative replication

Answer 3

parent strand + daughter strand

Question 4

origin of replication

Answer 4

a single, unique nucleotide sequence where DNA replication begins (prokaryotes)

Question 5

consensus sequence

Answer 5

short sequences of AT base pairs where replication begins. There are many of these (eukaryotes; prokaryotes have origin of replication)

Question 6

replication fork

Answer 6

when strands separate, v shape is formed where active synthesis occurs

Question 7

bidirectional

Answer 7

replication forks move in both directions away from the origin

Question 8

prepriming complex

Answer 8

proteins responsible for maintaining the separation of the parental strands and for unwinding the double helix ahead of the replication fork

Question 9

DnaA protein

Answer 9

Causes DNA to melt. Bind at origin of replication rich in AT base pairs . Requires ATP.

Question 10

SSB proteins

Answer 10

keep proteins separated in the area of replication origin, also protect the single stranded DNA from nucleases

Question 11

cooperative binding

Answer 11

binding of one SSB protein makes it easier for subsequent binding of SSB proteins

Question 12

DNA helicase

Answer 12

bind to SS dNA near the replication fork, forcing the double stranded parts nearby apart, unwinding the double helix. Require ATP

Question 13

positive supercoils

Answer 13

cord is twisted in the direction of tightening the coils

Question 14

negative supercoils

Answer 14

twisted in the direction of loosening the coils

Question 15

DNA topoisomerase

Answer 15

responsible for removing supercoils

Question 16

Type I DNA topoisomerase ( swivelase )

Answer 16

cut a single strand. have nuclease and ligase activities. do not require ATP, relaxes negative supercoils

Question 17

Type II DNA topoisomerase ( gyrase )

Answer 17

transient breaks in both strands. Can relieve both positive and negative supercoils. Requires ATP

Question 18

labile cell

Answer 18

continuously dividing, have a continuous cell cycle

Question 19

stable /quiescent cell

Answer 19

divide when needed

Question 20

permanent cell

Answer 20

does not divide

Question 21

mitosis

Answer 21

produces diploid cells

occurs in stable and labile cells

Question 22

meiosis

Answer 22

haploid cells
occurs in gametes
genetic variation

Question 23

prometaphase

Answer 23

ruptures nuclear membrane, aster formation

Question 24

gene expression

Answer 24

choosing which gene in the DNA will be used to convert into protein

Question 25

chromatin

Answer 25

unraveled DNA for transcription

Question 26

chromatid

Answer 26

1/2 of the chromosome

Question 27

chromosome

Answer 27

condensed DNA needed for mitosis

Question 28

histones

Answer 28

arginine and lysine | 5 classes: H2A, H2B, H3, H4, H1. all 2 molecules except H1

Question 29

heterochromatin

Answer 29

densely packed, transcriptionally inactive

Question 30

constitutive action of heterochromatin

Answer 30

always condensed and inactive (telomeres, centromeres)

Question 31

facultative action of heterochromatin

Answer 31

sometimes transcribed, sometimes not

Question 32

polynucleosome

Answer 32

nucleosomes that are packed more tightly

Question 33

exons

Answer 33

coding regions

Question 34

introns

Answer 34

noncoding intervening sequences

Question 35

microsatellite repeat sequences

Answer 35

2-3 repeating base pairs

Question 36

primase

Answer 36

synthesizes RNA primers, short stretches of RNA

Question 37

RNA primers

Answer 37

marks where replication will start. temporary RNA strands that will be removed eventually

Question 38

primosome complex

Answer 38

helicase + primase

Question 39

DNA polymerase III

Answer 39

catalyze chain elongation in 5' to 3' direction. (read template is 3' to 5')

Question 40

DNA polymerase I

Answer 40

removes RNA primers and fills space with corresponding base pairs in 5' to 3' direction. also proofreads

Question 41

Hayflick limit

Answer 41

number of times a cell divides before it stops

Question 42

senescence

Answer 42

with metabolic activity but does not divide anymore