module 11

Question 1

important requirements of cell division

Answer 1

after cell division, 2 daughter cells that result must each receive all the genetic amterial found in the single parent cell

parent cell needs to be big enough to divide in 2 so each daughter cell receives adequate cytoplasmic components

Question 2

prokaryotic and eukaryotic cells divide by:

Answer 2

p: binary fission

e: mitosis & cytokinesis

Question 3

binary fission

Answer 3

cell division in prokaryotes

circular DNA molecule

increase in cell size

division into 2 daughter cells -> each daughter cell receives one copy of replicated DNA

Question 4

explain the process of binary fission

Answer 4

proteins bind circular genome to inner surface of plasma membrane

dna replication starts at a certain spot on the molecule and travels around the circle in opposite directions

2 dna molecules are produced both of which are affixed to the cell membrane

2 dna attachment sites separate as cell elongates during binary fission

constriction forms at the midpoint of cell when it is about 2x its og size and dna molecules are well-separated

Question 5

eukaryotic vs prokaryotic cell division

Answer 5

eukary:
genome - large and linear
dna - nucleus
nuclear membrane must be broken down and then restored for complete DNA distribution into each daughter cell

prokary:
genome - small and circular
dna - cytoplasm
dna is attached to cell membrane and cell growth allows for separation into daughter cells

Question 5

what happens at the location of constriction in binary fission

Answer 5

new membrane is created

new cell wall is created

produces 2 daughter cells that are identical to parent cell

Question 5

the genome in eukaryotes are _______ and _______

Answer 5

large and linear

cell nucleus of eukaryote, the genetic material is isolated from the other components of cell

Question 5

2 distinct stages of cell cycle

Answer 5

M phase -> parent cell divides into 2 daughter cells

interphase -> time between 2 successive M phases

Question 5

M phase

Answer 5

parent cell divides into 2 daughter cells and consists of:

mitosis - separation of replicated chromosomes

cytokinesis - division of cytoplasm into 2 daughter cells

Question 6

interphase

Answer 6

occurs between 2 successive M phases, 10-14 hours

cell makes many preps for division including:

dna replication in nucleus

increase size of the cell

Question 6

stages of interphase

Answer 6

1. G1 phase
2. S phase
3. G2 phase
4. G0 phase

Question 7

G1 phase

Answer 7

first stage of interphase

increase in cell size and protein content

first gap phase

preparing cell for S phase

synthesis and activation of regulatory proteins

Question 8

S phase

Answer 8

second stage of interphase

synthesis phase -> replication of DNA

Question 9

G2 phase

Answer 9

third stage of interphase

second gap phase

cell prepares for M phase

Question 10

G0 phase

Answer 10

fourth stage of interphase

separate from G1 phase no active preparation for cell division

occurs in cells that do not actively divide

Question 11

dna replication is

Answer 11

semiconservative

2 stands of parental DNA unwind, each servig as a template strand

Question 11

at the end of DNA replication, each new DNA molecule consists of:

Answer 11

1 strand -> old parental
1 strand -> newly synthesized

semi-conservative!

Question 12

helicase

Answer 12

unwinds parental double helix at the replication fork

allows a single strand of DNA to be available for complementary base-pairs to be added by DNA polymerase

Question 13

single strand binding protein

Answer 13

binds to single stranded regions of parental strands

prevents the parental strands from coming back together

Question 14

enzymes needed to replicate DNA

Answer 14

DNA polymerase - extends RNA prmer

helicase - unwinds parental DNA strands

topoisomerase ii - relieves the stress of unwinding

single strand binding protein - stabilizes single strands of DNA (prevents parental from binding back together)

Question 15

DNA polymerase

Answer 15

adds basses to the nucleotide strand

requires 4 deoxyribonucleotides - dATP, dCTP, dGTP, dTTP

requires DNA template and RNA primer strand with a 3’-OH terminus

synthesize in 5’ - 3’ direction (transcription)

most can correct mistakes that may happen during replication

Question 16

topoisomerase

Answer 16

works upstream of replication fork

changes the supercoiled state of DNA - caused by unwinding of double helix at the replication fork

Question 17

what direction does DNA polymerase synthesize

Answer 17

5’ - 3’

Question 18

RNA primase

Answer 18

synthesizes a short piece of RNA that is complementary to a sequence of DNA parental strand

needed so DNA polymerase can add DNA bases to the growing chain

Question 19

leading strand

Answer 19

one strand grows toward replication fork and synthesized continuously 3' end pointing tward replication fork synthesized as one long continuous polymer as parental strand is unwound

Question 20

lagging strand

Answer 20

other strand grows away from replication strand and synthesized discont as fragments 3' end point away from replication fork synthesized in short discontinous strands called okazaki fragments new short piece of lagging strand is initiated at intervals as parental DNA strand is unwound at replication fork need to: add RNA primer DNA polymerase extend RNA primer replace rna primer with DNA bases

Question 21

newly synthesized DNA can only be elongated from ____ end

Answer 21

3' 2 daughter strands use diff replication mechanisms

Question 22

okazaki fragments

Answer 22

lagging strand os synthesized in small, discontinuous pieces necessary as synthesis only occurs in 5' - 3' direction

Question 23

RNA primase

Answer 23

add short RNA primers

Question 24

RNA primers

Answer 24

syhtesizes short piece of RNA complementary to DNA once primer has been synthesized, DNA polymerase takes over and elongates primer adding DNA nucleotides until it hits fragment in front diff DNA polymerase removes primer and replaces with DNA

Question 25

DNA ligase

Answer 25

when replacement of RNA primer wth new DNA is complete, fragments are joined together with DNA ligase completes sugar phosphate backbone of new DNA

Question 26

trombone model

Answer 26

leading and lagging strands can be synthesized at the same time by looping one of the strands of DNA as each new primer for an okazaki fragment is synthesized, lagging strand forms a loop that persists until the new lagging strand encounters the prev okazaki fragment

Question 27

how do DNA polymerases correct their own error

Answer 27

thru proofreading H bonds temporarily hold new nucleotide and base across way in template strand to check for errors activates cleavage function by removing incorrect base, then inserting the correct one

Question 28

special features of replication of circular chromosomes

Answer 28

1. single origin of replication 2. replication proceeds in both directions until forks meet and fuse on opposite side, completing 1 round of replication

Question 29

eukaryotic replication

Answer 29

linear dna multiple origins of replication -> multiple rep forks each rep fork proceeds bidirectionally

Question 30

lagging DNA needs __________________ to begin next okazaki fragment

Answer 30

enough single-stranded template DNA final primer is added abt 100 nucleotides from 3' end of template when primer is removed, a section of template DNA remains unreplicated