DNA

2

DNA Functions

• Stores genetic information to build and maintain a living organism

• Copies itself

3

James Watson & Francis Creek 1953

• Determined the three-dimensional structure of DNA

• One of the greatest discoveries in the history of science

• Nobel prize in 1962

4

• Made of repeating units called nucleotides

• Each nucleotide made of a sugar named deoxyribose, a phosphate and a base

5

DNA Nucleotide

Deoxyribose

Phosphate

Base =

6

Nucleotides Form a Double Strand

Deoxyribose

Phosphate

Base

7

DNA Molecule is Double Stranded

8

Base Pairing Rule

• Adenine pairs with Thymine

• Guanine pairs with Cytosine

9

DNA• Total length of DNA in each

cell is about 6 feet

• Wraps around proteins called histones

• Over 3 billion nucleotide pairs in human DNA!

10

DNA ReplicationDNA strands separate

DNA nucleotides attach to

each strand

11

Each new DNA

molecule will

be an exact copy of the

original

12

First, DNA strands separate

13

Second, an RNA attaches to DNA strand

DNA cannot start replication on its own

14

Third, DNA nucleotides are attached to DNA

strand

15

Fourth and final, the RNA is removed

16

DNA Errors• Replication is not 100% accurate

–Errors occur when copying DNA• DNA damaged

–Ultraviolet light–X-rays–Cigarette smoke–Nitrates (smoked meat)–Pesticides & Herbicides

17 The End