DNA Function, Structure, & Replication

DNA stands for

Deoxyribonucleic acid

Functions of DNA

1. Store & use info to direct activities of cell
2. Copy itself for new cells that are made

DNA made up of

2 long strands (helices)

Monomer of DNA

Nucleotides

DNA nucleotide has

1. 5-carbon sugar - deoxyribose
2. Phosphate group
3. Nitrogenous base

Nucleotides bond together in

Long strands

Sugar phosphate backbone

Makes up sides of double helix

4 nitrogenous bases

Adenine, guanine, thymine, cytosine

Nitrogenous base in RNA

Euracil

Purines

Adenine, guanine

Pyrimidines

Cytosine, thymine

Chargaff’s rule

A with T, C with G

Hydrogen bonds

Hold together 2 strands of DNA

Complementary strands

Nitrogen bases along 1 strand are an exact complement to an adjacent strand

2 rings

Purines

3 rings

Pyrimidines

Steps of DNA replication

1. Strand unzips
2. Complementary bases pair
3. Checks for errors & bonds S-P backbone

Job of helicase

Does the unzipping

Job of DNA polymerase

Adds complementary base pairs, checks for errors, & bonds S-P backbone

Semi-conservative replication

Each new strand = 1 new + 1 old

3’ strand

Leading

5’ strand

Lagging

How complementary strands run

Anti-parallel

How DNA polymerase can only travel

From 3’ → 5’

Okazaki fragments

What the lagging/ 5’ strand uses to replicate

Replication bubble

Where DNA replication occurs

Replication fork

Two strands that surround the replication bubble