1. Structure & Replication
Basics of DNA
Structure & Replication

2. DNA (Deoxyribonucleic Acid)
Polymer made of smaller monomers
nucleotides
Described as having a double helix
Twisted ladder
Outside = sugar phosphate backbone
Inside = base pairs

3. Nucleotides Repeating monomer Made of 3 smaller molecules Sugar
Deoxyribose
Phosphate
Base (4 Types)
Adenine
Thymine
Cytosine
Guanine

4. Base Pair Rule Adenine with Thymine Guanine with Cytosine
Joined together by hydrogen bonds
Pairs are in equal amounts
Form the steps in the DNA ladder

6. DNA Replication 3 Main Stages
Each strand acts as a template for the synthesis of a new strand
Reaction carried out by enzymes
3 Main Stages
Initiation – replication begins at an origin point
Elongation – new strands of DNA are synthesized
Follows the base pair rule
Termination – new strand of DNA is complete

7. Initiation: The strands separate
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8. Elongation: Each strand builds up its partner by adding the appropriate nucleotides
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The nucleotides are present in the nucleoplasm. The nuclear equivalent of cytoplasm
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Termination: 2 new and identical strands are complete.

9. Semi-Conservative Model

10. Chromosomes Found in nucleus
Chromosomes are tightly wound forms of DNA

11. Chromosomes & Genes Different chromosomes have different genes
Gene is a sequence of bases in a DNA molecule

12. Homologous Chromosomes
Chromosomes arranged in pairs = homologous chromosomes
One from mom and one from dad
Have the same genes in the same order
Slightly different DNA sequences

13. Humans have 23 pairs (46 Total)
Homologous Pairs
Humans have 23 pairs (46 Total)
Autosomes
Sex Chromosomes