1. Chapter 13 packet: DNA and Protein Synthesis Part I

2. Genes – the instructions for inherited traits
Genes are made of DNA, short for Deoxyribonucleic acid

3. Discovery of the structure of DNA
DNA is in the shape of a double helix – discovered by Franklin & Wilkins through X-ray diffraction of DNA (a)
Watson & Crick used above information to construct 1st model of DNA (b)

4. Structure of DNA DNA is a made of nucleotides
Nucleotides are composed of:
Phosphate
5-carbon sugar (deoxyribose)
1 of 4 nitrogen-containing bases - adenine (A), thymine (T), guanine (G), or cytosine (C)

5. Hydrogen bonds – holds 2 strands of nucleotides together
Shape: double helix (Two strands twist around each other)
Base pairing:
A & T
C & G (complementary base pairs)

6. DNA Replication
Purpose: makes an exact copy of DNA before the cell divides; ensures that each new cell gets a complete copy of the DNA
DNA
DNA
DNA
Replication
Cell Division
DNA

7. Steps:
Unwinding and separating DNA strands
Adding complementary bases
If parent strand has A  T is added
If parent strand has T  a is added
If parent strand has C  G is added
If parent strand has G  C is added
Formation of two identical DNA molecules

8. Overview of DNA replication

9. Ladder configuration and DNA replication

10. Website showing animation:
Each old strand (parent strand) of nucleotides serves as a template for each new strand (daughter strand).
Proofreading and repair limits error rate to less than 1 per billion nucleotides.
Website showing animation:
Video clip from class:

11. Enzymes involved in replication:
DNA Helicase – breaks the hydrogen bonds between base pairs during replication
DNA polymerase – adds new nucleotides to parent strand of DNA