EXAM 3 P2

Question 1

central dogma

Answer 1

all DNA in cells is double stranded (dsDNA)
the two strands are antiparallel
held together by base pairing (CGAT)

Question 2

purines

Answer 2

A and G

Question 3

pyrimidines

Answer 3

T and C

Question 4

single stranded DNA

Answer 4

only found in viruses

Question 5

DNA structure of bacteria

Answer 5

singular circular chromosome
single origin of replication
no histones

Question 6

DNA structure of archaea

Answer 6

single circular chromosome
1-3 origins of replication
contains histones

Question 7

DNA structure of eukarya

Answer 7

multiple linear chromosomes
man origins of replication on each chromosome
contains histones

Question 8

DNA polymerase

Answer 8

carries out DNA replication & repairs damaged DNA
requires an RNA primer to initiate synthesis
binds to the template strand and needs some form of nucleic acid (DNA/RNA) with a 3 prime end. bases are added to the 3’ end. synthesis is 5’ to 3’

Question 9

proofreading ability

Answer 9

used by DNA polymerase to ensure fidelity of DNA replication.
first method to make sure no mistakes are made
exonuclease activity

Question 10

explain the process of DNA replication

Answer 10

starts at the origin of replication. DNA poly starts moving around the circle in both directions (saves time)
point of movement around the circle is the replication fork, where the 2 strands are spread apart. once they meet at the bottom 2 identical progeny are produced
aka theta-form replication

Question 11

DnaA

Answer 11

protein that recognizes the origin of replication and recruits other proteins to start the process
determines when and where we start

Question 12

lagging strand

Answer 12

synthesis is discontinuous

made in a series of short pieces

Question 13

leading strand

Answer 13

synthesis is continuous

Question 14

helicase

Answer 14

replication protein that unwinds the two strands of the original molecule

Question 15

primase

Answer 15

protein that synthesizes an RNA primer

Question 16

single-stranded binding proteins

Answer 16

bind to a small amount of single stranded DNA to protect it damage and prevents reannealing to dsDNA

Question 17

okazaki fragments

Answer 17

series of short DNA pieces made in lagging strand synthesis, about 2000 bases long

Question 18

tau

Answer 18

holds everything together during replication

Question 19

DNA polymerase 3

Answer 19

does about 99% of chromosome replication in bacteria

really fast

Question 20

filling the gaps between okazaki fragments

Answer 20

DNA poly 3 synthesizes fragments and stops if no template strand is present, creating a gap in the DNA
DNA poly 1 uses exonuclease activity to remove RNA bases and fill in the gaps
the nicks are sealed by connecting the 3’ and 5’ ends
the two fragments are now one strand

Question 21

operons

Answer 21

has one promoter, multiple genes, and a terminator
polycistronic DNA, mRNA produced from the operon is also polycistronic
one promoter activates all the genes

Question 22

RNA polymerase

Answer 22

bacterial RNAP has 1 core enzyme made of 4 essential subunits, plus a sigma
eukaryotic has many subunits
core enzyme binds to sigma. sigma recognizes the promoter from a recognizable sequence of bases

Question 23

core enzymes

Answer 23

can bind to single strands but they aren’t smart
if mixed with DNA, it will start at random spots
doesn’t know where to stop

Question 24

-10 and -35 regions

Answer 24

areas of recognition for the sigma subunit

-10 is also the pribnow box

Question 25

+1

Answer 25

first base in the RNA product

place where transcription starts when RNA binds to the promoter

Question 26

consensus sequence for sigma A

Answer 26

the best sequence for sigma A to recognize promoters

TTGACA