Questions of the Day• Is heredity info. Protein or DNA?
– Griffith & Avery • Transforming principle
– Hershey & Chase• Bacteriophage experiments
• What is the structure of DNA?– Watson & Crick – essential structure– Rosalind Franklin
• X-ray chrystallography
• How does it work?
Replication
• Making a copy (synthesizing new DNA)
– Always attach at 3’ end• Towards replication fork
• Away from fork in “chunks”
– each new cell made has an exact copy of the original DNA from the parent cell
No Mistakes allowed!!
• “Typo’s” or mutations occur
• Proofreading enzymes repair mutations
• Only 1 error/billion nucleotides allowed
Mutations & Genetic Traits
• Sequences of DNA codes make up genes
• Any change to the code changes the gene
• Any change to the gene changes what we see in our phenotype