12-2 Chromosomes and DNA Replication

Pg. 295

A. DNA and Chromosomes

• 1. Prokaryotes have no nucleus; contain a single, circular strand of DNA.

A. DNA and Chromosomes• 2. Eukaryotes have 1000 times more DNA and

it is more complicated.

A. DNA and Chromosomes

• 3. DNA Length – E.Coli Bacteria (large intestine) 4,639,221 Nitrogen

Bases!! (1.6mm long)

A. DNA and Chromosomes

• 4. Chromosome Structure• a. Nucleus of a human cell contains 1 meter of

DNA!• b. Human DNA binds with protein called

histones to form chromatin.

B. DNA Replication

• 1. Replication is a copying process used by DNA to duplicate (copy) itself.

• 2. During DNA replication, the DNA molecule separates.

B. DNA Replication

• 3. Next, 2 new strands are made following the base pairing rules (A-T, C-G).

B. DNA Replication

• 4. Each original strand of the double helix serves as a template for the 2 new strands (Semi-Conservative).

B. DNA Replication

• 5. Many enzymes carry out replication (EX: Helicase unzips DNA) but the main enzyme is DNA Polymerase:– Joins nucleotides to make a DNA molecule– Proofreads DNA to correct mistakes

animation

Replicate this

DNA!!