What is DNA? Instructions for making proteins ‘Blueprint’ for who we are Where is it found? Found in the nucleus What does ‘DNA’ stand for? Deoxyribonucleic Acid

The Structure of DNA Double helix Structure of DNA: Twisted Ladder

Who Discovered DNA’s Structure? SCANDAL! Read all about it! Rosalind Franklin, James Watson, Francis Crick, & Maurice Wilkins discovered the shape (double helix) of DNA is 1953.

DNA is a polymer of Nucleotides. What are the 3 parts of a nucleotide? Review DNA is a polymer of Nucleotides. What are the 3 parts of a nucleotide?

DNA Subunit 3 components a sugar a phosphate group a nitrogen base Nucleotides DNA Subunit 3 components a sugar a phosphate group a nitrogen base

Nitrogen Bases 4 Types: Adenine Thymine Guanine Cytosine REMEMBER: At The Golf Course

Complementary Base Pairs Nitrogen bases always pair with the same partner Hydrogen bonds hold the bases together. A--T (At--The) G--C (Golf--Course)

What would the complementary strand be? A-T-C-C-G-T-T-T-A-C-A-G-G-A THINK! What would the complementary strand be? A-T-C-C-G-T-T-T-A-C-A-G-G-A T-A-G-G-C-A-A-A-T-G-T-C-C-T

Nucleotides join to form a long chain (polymer) Sides of the ladder: How DNA Strands Form Nucleotides join to form a long chain (polymer) Sides of the ladder: Sugar + Phosphate Rungs of ladder: Nitrogen bases bond together (with H-bond)

How is DNA Organized? Histone proteins act like spools that wind up DNA to keep it organized.

During Interphase… How does DNA exist? Unwound! (Chromatin)

Why Chromatin? What happens during Interphase? DNA Replicates! DNA is uncoiled so that enzymes can unzip it. When it is unzipped, DNA can be duplicated.

DNA Replication Process where DNA is copied Occurs before mitosis and meiosis (during interphase!)

DNA Replication During replication, each strand of the double helix serves as a template for the formation of the new strand of nucleotides.

Important enzymes DNA helicase- breaks the weak hydrogen bonds between nitrogen bases to unzip DNA . DNA polymerase- links nucleotides together to form DNA strands. Ligase- “Glues” Okazaki fragments back together to form a complete strand.

How DNA Duplication Occurs Step 1: Enzymes (Helicase) unzip the DNA strand T A G C ENZYME

Step 2: Free nucleotides bind to the complementary bases Step 2: Free nucleotides bind to the complementary bases. (DNA Polymerase) T A G C

Result: 2 Complete Strands! Old T A G C New New Old

DNA Replication (5’-3’) It happens all over the strand!

Semiconservative Replication: one of the original strands is present in each new strand of DNA.

Makin’ Copies for Mitosis: Growth, Repair, and Reproduction!

The Central Dogma of Genetics DNA RNA Proteins