Science Dna Replication

Front 1

What are the two major steps of DNA replication?

Back 1

1. DNA is locally denatured(or unwound) to separate the two template strands in order to prepare them for base pairing.

2. New nucleotides are attached by covalent bonding to each growing strand. The sequence of the new strand is determined by the original strand.

Front 2

What are the two ends to our DNA molecule?

Back 2

3'-ends in -OH
5'-ends in a phosphate

Front 3

Origin of replication

Back 3

a sequence of nucleotides that the replication complex can attach to in order to start replication. (mostly A and T because it's easier to break the double bonds)

Front 4

Replication complex

Back 4

contains molecules that aid in DNA replication such as:DNA helicase, single strand binding proteins, DNA polymerase, DNA ligase.

Front 5

DNA helicase

Back 5

splits open the DNA by separating the nitrogen-containing bases by using hydrolysis which eliminates the hydrogen bonds.

Front 6

Single Strand binding proteins

Back 6

bind to the individual strands and prevent them from twisting/recoiling

Front 7

Difference between the leading and lagging strand

Back 7

the nucleotide strands are anti-parallel
-during replication we read the template 3' --> 5'
-we created the new strand 5' --> 3'

Front 8

lagging strand

Back 8

the strand where replication occurs in fragments and replication moves opposite direction of helicase

Front 9

leading strand

Back 9

replication occurs continuously in the same direction the helicase moves.

Front 10

Step One (replication) on leading

Back 10

Primase attaches to the 3' end of the template and creates a primer.

Front 11

What is primase?

Back 11

a sequence of RNA nucleotides typically about 10-15 nucleotides long.

Front 12

Step two of replication (leading)

Back 12

DNA polymerase III can now jump on the leading strand at the primer and begins making the new DNA strands by adding nucleotides.

Front 13

Step 3 of replication (leading)

Back 13

When DNA polymerase III hits another primer or comes to the end of the DNA template it falls off.

Front 14

Step 4 of replication (leading)

Back 14

DNA polymerase I joins the primer, cuts it out, adds DNA in its place.

Front 15

Step 5 of replication (leading)

Back 15

DNA ligase travels down the strand sticking any fragments together.

Front 16

Replication step six (leading)

Back 16

Template and new strand coil together to form 1 new DNA molecule.

Front 17

Replication step one (lagging)

Back 17

primase adds primer to exposed template strand, polymerase III adds new DNA nucleotides

Front 18

Replication step two (lagging)

Back 18

-helicase continues to unwind exposing nucleotides in front of the primer
-now a new primase joins the template, adds another primer
-poly 3 joins the primer and adds new nucleotides
-poly 3 falls off when it hits primer

Front 19

Replication step three (lagging)

Back 19

These form okasaki fragments. primer, and DNA nucleotides on new strands
-polymerase I joins the DNA, cuts off the RNA and adds DNA nucleotides
-ligase glues the fragments together to get 1 continuous strand.

Front 20

Proofreading and repair

Back 20

all 3 DNA polymerases have the ability to proofread the DNA sequence and make repairs.

Front 21

How does it work?

Back 21

DNA polymerases will remove the error and replace with a new nucleotide. Ligase will glue it in place.

Front 22

Mismatch repair

Back 22

occurs when there are mismatched bases
DNA polymerase goes in, removes the wrong base and adds the correct one

Front 23

Excision repair

Back 23

occurs when enzymes discover that 1 or more of the nucleotides are damaged.
excise repair proteins cut out the damaged nucleotide and a few adjacent nucleotides.
polymerase (I+II) replace the gaps with nucleotides. Ligase glues it together.