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If you unwrap all the DNA you have in all your

cells, you could reach the moon!

6000 times!!!

Deoxyribonucleic Acid (DNA)

Primary Function = to store and transmit the genetic information that tells cells which proteins to make and when to make them.

an ORGANIC compound made up of repeating

subunits called NUCLEOTIDES composed of TWO long chains

of nucleotides

3 PARTS:

1. Sugar Molecule – deoxyribose

2. Phosphate Group – phosphorous(P) and oxygen (O)

3. Nitrogen Base – adenine(A), cytosine(C), guanine(G), and thymine(T)

Diagram of a Nucleotide

1. Adenine 2. Guanine

Purines have two

rings

And come in two types:

Nitrogen bases come in two types:

2. Thymine1. Cytosine

Pyrimidines

have ONE ring

And come in two types:

Nitrogen bases come in two types:

Complimentary Base Pairing

Describes the pairing behavior of the bases.

TWO rules:1. Cytosine

bonds with Guanine

2. Adenine bondswith Thymine

In 1953, JAMES WATSON & FRANCIS CRICK suggested a model for the structure of

DNA.

Two nucleotide strands wrap around each other to form a double spiral (spiral staircase)

The Double Helix

Image of the Double Helix

= The process of copying DNA.

Overall: Two nucleotide chains separate and serve as TEMPLATE for a new nucleotide chain.

1. Helicase enzymes untwist and unzip the DNA helix. (A replication fork is now formed.)

2. DNA primase enzyme adds a primer to each side of the open strand.

3. DNA polymerase adds the new nucleotides one at a time.

4. Lastly, DNA ligase enzyme “glues” nucleotides together on the lagging strand.

***You are left with 2 exactly identical strands of DNA

double helix.***

Original strands of

DNA

Original

Original

O ON NNew New