Lecture 29

Question 1

initiation

Answer 1

where the DNA gyrase uncoils the chromosome; SSBP creates a gap; helicase unzips strands; usually starts at an AT rich area because it is easier to break apart

Question 2

elongation

Answer 2

the addition of nucleotides to the 3’ end of a growing RNA chain during transcription

Question 3

termination

Answer 3

site located roughly opposite oriC on circular chromosome

Question 4

DNA gyrase

Answer 4

uncoils chromosome at a specific location called OriC (initiation site) also unlink final daughter molecules

Question 5

helicase

Answer 5

unzips the 2 DNA strands by breaking H bonds between base pairs, creates a forked DNA molecule (replication fork

Question 6

SSBP

Answer 6

single stranded binding proteins; bind to DNA at OriC and creates a gap between the strands

Question 7

primase

Answer 7

must add RNA primer to each DNA strand

Question 8

DNa polymerase III

Answer 8

slides down the strand adding complementary nucleotides

Question 9

clamp

Answer 9

attaches DNA polymerase to the strand of primer

Question 10

Clamp loader

Answer 10

loads protein clamp onto strand

Question 11

DNA polymerase I

Answer 11

reads original NDA in 5’ to 3’ direction, removing primers on lagging strand
- can only add new nucleotides to pre-existing 3’ OH groups while moving towards the fork

Question 12

DNA ligase

Answer 12

makes a reaction between 5’ OH and top O of a PO4 group, after ligase binds the two, it removes the ‘break” in the DNA strand

Question 13

E. coli

Answer 13

prokaryotic cell with floating DNA (no nucleus); replicates through binary fission

Question 14

oriC

Answer 14

initiation site; DNA gyrase uncoils the chromosome at this site

Question 15

supercoiling

Answer 15

DNA inside the cell twists up like rubber band so it will fit

Question 16

initiator proteins

Answer 16

proteins that recognize specific DNA sequence within the origin of replication, this is where helicase attaches to the template strand and starts to unwind the DNA into two strands

Question 17

replication fork

Answer 17

helicase unzips DNA strands by breaking the H bonds between base pairs and creating a forked DNA molecule

Question 18

primer

Answer 18

synthesizes short stretches of RNA base pairs that function as primers for DNA polymerase

Question 19

antiparallel

Answer 19

polarity runs opposite 5’ to 3’ attached to 3’ to 5’

Question 20

discontinuous

Answer 20

synthesis occurs in short segments called Okazaki fragments

Question 21

leading strand

Answer 21

continuous synthesis

Question 22

DNA ligase

Answer 22

connects Okazaki fragments

Question 23

lagging strand

Answer 23

discontinuous synthesis

Question 24

okazaki fragments

Answer 24

short segments in which synthesis on the lagging strand occurs

Question 25

nucleotides

Answer 25

ATCG; complementary to template, form phosphodiester bonds, and bond with bases on template

Question 26

phosphodiester bond

Answer 26

occurs when two of the hydorxyl groups react with hydroxyl groups on other molecules to form two ester bonds, linkage between 3 carbon atom of one sugar and 5 carbon atom of another

Question 27

replisome

Answer 27

enzymes involved in DNA replication; the entire enzyme is composed of DNA ligase, polymerase I and III, helicase and primase