A

T

A T

KEY:

C

G

C G

- Phosphate

- Sugar

- Adenine

- Thymine

- Cytosine

- Guanine

A T

A T

C G

C G

C G

T A

T A

This single DNA molecule is ready to be brokenby DNA Helicase at the bottom, at the AT bond.

5’

3’5’

3’

A

T

A T

KEY:

C

G

C G

- Phosphate

- Sugar

- Adenine

- Thymine

- Cytosine

- Guanine

A T

A T

C G

C G

C G

T A

T A

DNA Helicase begins splitting the DNA at the origin of replication, which is atan AT bond. AT bonds are only doublebonds, whereas CG bonds are triple bonds. Helicase breaks a double bondeasier, so it looks for an AT bond.

5’

3’

3’

5’

A

T

A T

KEY:

C

G

C G

- Phosphate

- Sugar

- Adenine

- Thymine

- Cytosine

- Guanine

A T

A T

C G

C G

C G

T A

T A

5’

5’3’

3’

A

T

A T

KEY:

C

G

C G

- Phosphate

- Sugar

- Adenine

- Thymine

- Cytosine

- Guanine

A T

A T

C G

C G

C G

T A

T A

5’

5’3’

3’

A

T

A T

KEY:

C

G

C G

- Phosphate

- Sugar

- Adenine

- Thymine

- Cytosine

- Guanine

A T

A T

C G

C G

C G

T A

T A

5’

5’3’

3’ Helicase has finished unwinding the DNA molecule, leaving to strands forreplication.

A

T

A

KEY:

C

G

C

- Phosphate

- Sugar

- Adenine

- Thymine

- Cytosine

- Guanine

A

A

C

C

C

T

T

5’

3’

DNA replication occurs in a 5’ to 3’ pattern,so the left strand becomes the first to geta new strand attached.

T

A

T

A

KEY:

C

G

C

- Phosphate

- Sugar

- Adenine

- Thymine

- Cytosine

- Guanine

A

A

C

C

C

T

T

5’

3’

DNA replication occurs in a 5’ to 3’ pattern,so the left strand becomes the first to geta new strand attached.

T

G

T

A

T

A

KEY:

C

G

C

- Phosphate

- Sugar

- Adenine

- Thymine

- Cytosine

- Guanine

A

A

C

C

C

T

T

5’

3’

DNA replication occurs in a 5’ to 3’ pattern,so the left strand becomes the first to geta new strand attached.

T

G

T

T

G

G

A

A

T

A

KEY:

C

G

C

- Phosphate

- Sugar

- Adenine

- Thymine

- Cytosine

- Guanine

A

A

C

C

C

T

T

5’

3’

The leading strand (left strand) finishes replication and becomes a new DNA molecule.

T

G

T

T

G

G

A

G

AA

3’

5’

A

T

T

KEY:

C

G

G

- Phosphate

- Sugar

- Adenine

- Thymine

- Cytosine

- Guanine

T

T

G

G

G

T A

A 5’

3’ Since DNA replication happens in a 3’to 5’ pattern, the right strand, or the lagging strand, replicates a new strand after the leading strand. However, DNAcan’t replicate this way, so DNA Primaseis added to temporarily make it a 5’ to3’ strand.

A

C

A

A

T

T

KEY:

C

G

G

- Phosphate

- Sugar

- Adenine

- Thymine

- Cytosine

- Guanine

T

T

G

G

G

T A

A 5’

3’ Since DNA replication happens in a 3’to 5’ pattern, the right strand, or the lagging strand, replicates a new strand after the leading strand. However, DNAcan’t replicate this way, so DNA Primaseis added to temporarily make it a 5’ to3’ strand.

A

C

A

A

C

A

T

T

KEY:

C

G

G

- Phosphate

- Sugar

- Adenine

- Thymine

- Cytosine

- Guanine

T

T

G

G

G

T A

A 5’

3’ Since DNA replication happens in a 3’to 5’ pattern, the right strand, or the lagging strand, replicates a new strand after the leading strand. However, DNAcan’t replicate this way, so DNA Primaseis added to temporarily make it a 5’ to3’ strand.

A

C

A

A

C

C

C