DNA ReplicationBy: Hannah Duminske

DNA stands for Deoxyribonucleic Acid. This is a molecule that contains genetic instructions used for development and functioning in organisms.

G

G

G

ATC

G = Guanine

= Cytosine

= Thymine

= Adenine

= Phosphate

= Sugar

A

A

A

A

A

T

T

T

T

T

C

C

C

GC

Sugar Phosphate Backbone

Nitrogenous Base

5

5

3

3

G

G

G

A

A

A

A

A

T

T

T

T

T

C

C

C

GC

= Helicase

Helicase; Helicase is what unwides the double Stranded dna at the place where DNA replication is taking place. It does this by breaking the hydrogen bonds that hold together the complementary bonds.

G

G

G

A

A

A

A

A

T

T

T

T

T

C

C

C

GC

= Helicase “unzipping” the strands

Primase; it’s an enzyme involved in DNAreplication. It creates RNA primer. Is alsoUsed for DNA stabilization.

G

G

G

T

T

T

T

T

G

A

A

A

A

A

C

C

C

C

After the helicase unzips the DNA Strands it will begin replication.

A

A

A

A

A

C

C

C G

G

G

T

T

T

T

T

GC

T

G

= DNA Polymerase: this will add the nucleotides continuously onto the firststrand.

A

A

A

A

A

C

C

C G

G

G

T

T

T

T

T

GC

T

T

G

A

A

A

A

A

C

C

C G

G

G

T

T

T

T

T

GC

G

T

T

G

This is the leading strand: It replicates continously

A

A

A

A

A

C

C

C

C

G

T

T

T

G

G

G

G

T

T

T

T

T

G

A

A

C

A

A

A

A

A

C

C

C

C

G

G

T

T

T

G

G

G

G

T

T

T

T

T

G

A

A

C

This is the lagging strand, it replicates discontinuously in fragments. These are called Okazakifragments.

Okazaki Fragment

A

A

A

A

A

C

C

C

C

G

G

T

T

T

T

G

G

G

G

T

T

T

T

T

G

A

A

C

A

C

C

A

A

A

A

A

C

C

C

C

G

G

G

T

T

T

T

G

G

G

G

T

T

T

T

T

G

A

A

C

A

C

C

A

A

A

A

A

C

C

C

C

G

G

G

T

T

T

T

T

G

G

G

G

T

T

T

T

T

G

A

A

C

A

C

C

A

A

A

A

A

C

C

C

C

G

G

G

T

T

T

T

T

G

G

G

G

T

T

T

T

T

G

A

A

C

A

C

C

A

A

A

A

A

C

C

C

C

G

G

G

T

T

T

T

T

G

G

G

G

A

A

A

A

A

T

T

T

T

T

C

C

C

GC

5

3 5

3 5

3

3

5

RECAPDNA replication happens in the S phase which is before prophase. First you start off with one double stranded DNA molecule. This is deoxyribonucleic acid, DNA for short. DNA is made up of a sugar phosphate backbone and complementary base pairs. A goes with T and C goes with G which are held together by hydrogen bonds.

Then helicase comes into the picture. Helicase is an enzyme which “unzips” the two strands, splitting them. Then they begin replicating. The leading strand will start. The leading strand is the strand that continuously elongates up. While the lagging strand replicates in a discontinuous fashion by forming in okazaki fragments. After this, the replication is finished.

PurposeThe purpose of DNA replication is to

make sure that the genetic material which is found in the coding on the DNA can be passed from original cell to the next. This will also lead to the transferring of traits.

MutationWhat is a mutation? In genetics a

mutation is a change in the nucleotide sequence. Examples of things mutations can cause would be Huntington’s disease, cancers, cystic fibrosis, and sickle cell anemia. A mutation can be spontaneous or caused by things such as radiation and certain chemicals.