DNA ReplicationBy: Lucas Burkett

T

T

A

A

TA

T

T

CG

CG

C G

C

A

A

G

-Phosphate

-Deoxyribose

A -Adenine

T -Thymine

G -Guanine

C -Cytosine

5’ 3’

3’ 5’

DNA Replication occurs to allow a DNA strand to make another identical matching strand.

T

T

A

A

TA

T

T

CG

CG

C G

C

A

A

G

-Phosphate

-Deoxyribose

A -Adenine

T -Thymine

G -Guanine

C -Cytosine

Nucleotide5’ 3’

3’ 5’

T

T

A

A

TA

T

T

CG

CG

C G

C

A

A

G

-Phosphate

-Deoxyribose

A -Adenine

T -Thymine

G -Guanine

C -Cytosine

5’ 3’

3’ 5’

DNA Replication occurs during the S phase (synthesis) of mitosis - which is part of the interphase.

-Phosphate

-Deoxyribose

A -Adenine

T -Thymine

G -Guanine

C -Cytosine

T

T

A

A

A

T

T

CG

CG

C G

C

A

A

G

T

Hel

icas

e

5’ 3’

3’ 5’

DNA Helicase unwinds the double-stranded DNA at the origin of replication by breaking the hydrogen bonds between the strands. Helicase starts at an Adenine-Thymine bond because it has a double bond where a Guanine-Cytosine has a triple bond.

-Phosphate

-Deoxyribose

A -Adenine

T -Thymine

G -Guanine

C -Cytosine

T

T

A

A

A

T

T

CG

CG

C G

C

A

A

G

T

Hel

icas

e

5’ 3’

3’ 5’

When DNA is unzipping, single stranded binding proteins bind to the DNA for stabilization.

-Phosphate

-Deoxyribose

A -Adenine

T -Thymine

G -Guanine

C -Cytosine

T

T

A

A

A

T

T

CG

G

C G

C

A

A

G

T

C

Hel

icas

e

5’ 3’

3’ 5’

As DNA Helicase is splitting the DNA strand, DNA Polymerase III adds the matching nucleotides to the left side of the DNA strand since it has the 3’ on the bottom of the strand. This happens in a continuous fashion.

-Phosphate

-Deoxyribose

A -Adenine

T -Thymine

G -Guanine

C -Cytosine

T

T

A

A

A

T

T

CG

G

C G

C

A

A

G

T

C

Hel

icas

e

5’ 3’

3’ 5’

Since the right side as the 5’ end on the bottom, DNA Primase has to add an RNA primer. This marks a starting point for DNA Polymerase II to add the matching nucleotides on. As the DNA strand continues to get split, more RNA primers are added. The space between each RNA primer is called okazaki fragments. This process happens discontinuously.

-Phosphate

-Deoxyribose

A -Adenine

T -Thymine

G -Guanine

C -Cytosine

TA

A

A

T

T

CG

G

C G

C

A

A

G

T

C

T

Hel

icas

e

5’ 3’

3’ 5’

DNA Polymerase I removes the RNA primer from the previous lagging strand and replaces it with DNA.

-Phosphate

-Deoxyribose

A -Adenine

T -Thymine

G -Guanine

C -Cytosine

TA

A

A

T

T

CG

G

G

C

A

A

G

T

C

T

CH

elic

ase

5’ 3’

3’ 5’

DNA Ligase forms a phophodiester bond between the 3’ end of the growing strand and the 5’ phosphate end in front of it. This finalizes the connection of okazaki fragments.

-Phosphate

-Deoxyribose

A -Adenine

T -Thymine

G -Guanine

C -Cytosine

TA

A

A

T

T

CG

G

G

C

A

A

G

T

C

T

C

Hel

icas

e

5’ 3’

3’ 5’

-Phosphate

-Deoxyribose

A -Adenine

T -Thymine

G -Guanine

C -Cytosine

TA

A

A

T

T

G

G

G

C

A

A

G

T

C

T

C

C

Hel

icas

e

5’ 3’

3’ 5’

-Phosphate

-Deoxyribose

A -Adenine

T -Thymine

G -Guanine

C -Cytosine

A

A

A

T

T

G

G

G

C

A

A

G

T

C

T

C

C

T

Hel

icas

e

5’ 3’

3’ 5’

-Phosphate

-Deoxyribose

A -Adenine

T -Thymine

G -Guanine

C -Cytosine

A

A

A

T

T

G

G

G

C

A

A

G

T

C

T

C

C

T

-Phosphate

-Deoxyribose

A -Adenine

T -Thymine

G -Guanine

C -Cytosine

A

A

A

T

T

G

G

C

C G

A

A

G

T

C

T

C

T

-Phosphate

-Deoxyribose

A -Adenine

T -Thymine

G -Guanine

C -Cytosine

A

A

A

T

T

G

G

G

C

A

A

G

T

C

T

C

C

T

-Phosphate

-Deoxyribose

A -Adenine

T -Thymine

G -Guanine

C -Cytosine

A

A

A

T

T

G

G

C

C G

A

A

G

T

C

T

C

T

-Phosphate

-Deoxyribose

A -Adenine

T -Thymine

G -Guanine

C -Cytosine

A

A

A

T

T

G

G

G

C

A

A

G

T

C

T

C

C

T

-Phosphate

-Deoxyribose

A -Adenine

T -Thymine

G -Guanine

C -Cytosine

A

A

A

T

T

G

G

G

C

A

A

G

T

C

T

C

C

TT AA mutation can occur from errors in the process of replication or from unrepaired damage to DNA. A mutation is a change of the nucleotide sequence of an organism.

-Phosphate

-Deoxyribose

A -Adenine

T -Thymine

G -Guanine

C -Cytosine

A

A

A

T

T

G

G

G

C

A

A

G

T

C

T

C

C

TT A

C

T A

G

Mutations can cause different diseases and observable characteristics. They play a part in both normal and abnormal biological processes including evolution, cancer, and the development of the immune system.

-Phosphate

-Deoxyribose

A -Adenine

T -Thymine

G -Guanine

C -Cytosine

A

A

A

T

T

G

G

G

C

A

A

G

T

C

T

C

C

TT A

C

T A

G

A T

-Phosphate

-Deoxyribose

A -Adenine

T -Thymine

G -Guanine

C -Cytosine

A

A

A

T

T

G

G

G

C

A

A

G

T

C

T

C

C

TT A

C

T A

G

A T

G C

-Phosphate

-Deoxyribose

A -Adenine

T -Thymine

G -Guanine

C -Cytosine

A

A

A

T

T

G

G

G

C

A

A

G

T

C

T

C

C

TT A

C

T A

G

A T

G C

T A

-Phosphate

-Deoxyribose

A -Adenine

T -Thymine

G -Guanine

C -Cytosine

A

A

A

T

T

G

G

G

C

A

A

G

T

C

T

C

C

TT A

C

T A

G

A T

G C

T A

A T

-Phosphate

-Deoxyribose

A -Adenine

T -Thymine

G -Guanine

C -Cytosine

A

A

A

T

T

G

G

G

C

A

A

G

T

C

T

C

C

TT A

C

T A

G

A T

G C

T A

A T

C G

-Phosphate

-Deoxyribose

A -Adenine

T -Thymine

G -Guanine

C -Cytosine

A

A

A

T

T

G

G

G

C

A

A

G

T

C

T

C

C

TT A

C

T A

G

A T

G C

T A

A T

C G

G C

-Phosphate

-Deoxyribose

A -Adenine

T -Thymine

G -Guanine

C -Cytosine

A

A

A

T

T

G

G

G

C

A

A

G

T

C

T

C

C

TT A

C

T A

G

A T

G C

T A

A T

C G

G C

T A

-Phosphate

-Deoxyribose

A -Adenine

T -Thymine

G -Guanine

C -Cytosine

A

A

A

T

T

G

G

G

C

A

A

G

T

C

T

C

C

T A

A

A

T

T

G

G

G

C

A

A

G

T

C

T

C

C

T

-Phosphate

-Deoxyribose

A -Adenine

T -Thymine

G -Guanine

C -Cytosine

TA

A

A

T

T

G

G

G

C

A

A

G

T

C

T

C

C

TA

A

A

T

T

G

G

G

C

A

A

G

T

C

T

C

C

-Phosphate

-Deoxyribose

A -Adenine

T -Thymine

G -Guanine

C -Cytosine

TA

A

A

T

T

CG

G

G

C

A

A

G

T

C

T

C

TA

A

A

T

T

CG

G

G

C

A

A

G

T

C

T

C

-Phosphate

-Deoxyribose

A -Adenine

T -Thymine

G -Guanine

C -Cytosine

TA

A

A

T

T

CG

G

G

C

A

A

G

T

C

T

C

TA

A

A

T

T

CG

G

G

C

A

A

G

T

C

T

C

-Phosphate

-Deoxyribose

A -Adenine

T -Thymine

G -Guanine

C -Cytosine

TA

A

A

T

T

CG

G

C G

C

A

A

G

T

C

T

TA

A

A

T

T

CG

G

C G

C

A

A

G

T

C

T

-Phosphate

-Deoxyribose

A -Adenine

T -Thymine

G -Guanine

C -Cytosine

T

T

A

A

A

T

T

CG

G

C G

C

A

A

G

T

C

T

T

A

A

A

T

T

CG

G

C G

C

A

A

G

T

C

-Phosphate

-Deoxyribose

A -Adenine

T -Thymine

G -Guanine

C -Cytosine

T

T

A

A

A

T

T

CG

G

C G

C

A

A

G

T

C

T

T

A

A

A

T

T

CG

G

C G

C

A

A

G

T

C

-Phosphate

-Deoxyribose

A -Adenine

T -Thymine

G -Guanine

C -Cytosine

T

T

A

A

A

T

T

CG

CG

C G

C

A

A

G

T

T

T

A

A

A

T

T

CG

CG

C G

C

A

A

G

T

-Phosphate

-Deoxyribose

A -Adenine

T -Thymine

G -Guanine

C -Cytosine

T

T

A

A

A

T

T

CG

CG

C G

C

A

A

G

T

T

T

A

A

A

T

T

CG

CG

C G

C

A

A

G

T

-Phosphate

-Deoxyribose

A -Adenine

T -Thymine

G -Guanine

C -Cytosine

T

T

A

A

TA

T

T

CG

CG

C G

C

A

A

G

T

T

A

A

TA

T

T

CG

CG

C G

C

A

A

G

5’ 3’

3’ 5’

5’ 3’

3’ 5’

After all of the steps of DNA Replication, you have two identical strands of DNA. DNA Replication can then happen again and again.