Chapter 28 DNA-Life’s Code

Chapter 28DNA-Life’s Code

•Learn the parts of DNA•Understand DNA replication•Understand how DNA mutates•Biotechnology

Bacterial Transformation Experiment

• Fred Griffith

• 1928

• Injected mice with bacteria

• Smooth:pneumonia bacteria

• Rough: harmless bacteria

Transforming Principle

• Chemical that causes harmless bacteria to transform into pneumonia

• Transforming principle = DNA

DNA

• Chemical of heredity

• Deoxyribonucleic Acid

1. Sugar (Deoxyribose)

2. Phosphate

3. Nitrogen Base

Nucleotide

• 3 parts combined into one subunit

• Join together to form an entire DNA

4 Nitrogen Bases

1. A: adenine

2. G: guanine

3. T: Thymine

4. C: Cytosine

Base Pairing

• Only certain bases can bond with one another

1. A bonds T

2. G bond C

DNA Structure

• Double Helix = twisted ladder

• 2 chains: nucleotides joined together

• Rungs: base – hydrogen bond – base

• Sides: sugar and acid

Replication of DNA

• Copies of DNA chain made during Interphase

http://www.pbs.org/wgbh/aso/tryit/dna/#

Steps to Replication

1. An enzyme “unzips” the double helix

2. Unzips by breaking Hydrogen bonds

3. A new enzyme moves along the parent chain placing new nucleotides

4. Match base pairs; A-T; G-C

5. DNA molecule is a parent chain bonded to a new chain