Dna Replication

Front 1

Where does DNA replication begin?

Back 1

At the origin of replication, each bacteria only has one but eukaryotes have many

Front 2

Which direction does DNA synthesis proceed?

Back 2

Proceeds 5' -> 3' bidirectionally

Front 3

What important DNA sequences are in the oriC?

Back 3

1. AT rich regions
2. and DnaA boxes

Front 4

Why is the A-T rich region at the OriC such a good starting spot?

Back 4

b/c there is only 2 h-bonds b/e A=T; so the strand is weaker and easier to pull apart in these areas

Front 5

What initiates DNA replication? how does that work?

Back 5

Binding of DnaA proteins to the DnaA box. Binding of DnaA proteins to the DnaA box causes the region to wrap around the DnaA proteins and separates the strands at the A-T region

Front 6

What binds to the DNA sequence after DnaA protein? where does it bind?

Back 6

DnaB protein or "helicase"; which binds to the origin

Front 7

What does helicase do?

Back 7

Moves along the separated DNA strands bidirectionally to separate the strands

Front 8

What prevents the DNA strands from rejoining together after helicase separates them?

Back 8

Single-stranded binding protein

Front 9

How does Helicase separate the DNA strands?

Back 9

By breaking the hydrogen bonds b/e the base pairs, using ATP as an energy source

Front 10

What do the actions of helicase generate?

Back 10

Helicase generates supercoiling ahead of it

Front 11

What does DNA gyrase do?

Back 11

Removes supercoils from DNA

Front 12

What does single-stranded binding protein do?

Back 12

Keeps the DNA strands separated

Front 13

What does DNA primase do?

Back 13

creates short RNA primers which prepares the DNA strands for synthesis

Front 14

What molecule in DNA replication is a type II isomerase?

Back 14

DNA gyrase

Front 15

What molecule generates negative supercoiling? positive supercoiling?

Back 15

DNA gyrase generates negative supercoiling, DNA helicase generates positive supercoiling

Front 16

How can gyrase be inhibited? what assists these antibiotics?

Back 16

By competitive inhibition using aminocoumarins (antibiotics) by inhibiting ATPase activity at Gyrase's active site

Quinolones bind to these enzymes and prevent them from releasing from DNA

Front 17

How does DNA polymerase III work?

Back 17

Works by using a RNA PRIMER to covalently link two nucleotides together, so for example if there was no RNA primer polymerase wouldn't be able to function

Front 18

What DNA replication enzyme is self-correcting?

Back 18

DNA polymerase III

Front 19

What enzyme has separate catalytic sites that removes unpaired residues at a terminus?

Back 19

DNA polymerase III

Front 20

Which direction does DNA polymerase III replicate DNA? proofread DNA?

Back 20

DNA polymerase III replicates DNA 5'->3', but it proofreads 3'->5'

Front 21

What site does DNA polymerase III move a mismatched nucleotide to if the nucleotide is wrong?

Back 21

The "E" or error site

Front 22

What is the name of the discontinuous pieces of DNA copied on the lagging strand?

Back 22

Okazaki fragments

Front 23

What removes the RNA primers on DNA?

Back 23

Another DNA polymerase

Front 24

What does DNA ligase do?

Back 24

Seals in the gaps left in the sugar-phosphate backbone by removal of the RNA primers

Front 25

What are "nicks"? What are gaps?

Back 25

Nicks = Single strand breaks in double stranded DNA, basically a disruption in the phosphodiester backbone of DNA

Gaps = At least one nucleotide is missing

Front 26

What strand will always have a RNA primer at the end?

Back 26

The lagging strand

Front 27

What does telomerase do?

Back 27

Adds telomerase to the ends of DNA which are tandem repeats of the sequence TTGGG

Front 28

How does telomerase work?

Back 28

By binding to the 3' end of the parental strand and extending it using RNA-templated DNA synthesis, the extension allows DNA polymerase to complete replication of the lagging strand