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Chapter 16
The Molecular Basis of Inheritance
Scientists like Mendel and Morgan showed us how genes behave…
Chapter 16
The Molecular Basis of Inheritance
Scientists like Mendel and Morgan showed us how genes behave but no one knew what genes were made of, until…
Chapter 16
The Molecular Basis of Inheritance
Avery (1928)
Chapter 16
The Molecular Basis of Inheritance
Avery (1928)
Two strains of pneumonia bacteria:
S (smooth) = deadly
R (rough) = harmless.
Chapter 16
The Molecular Basis of Inheritance
Avery (1928)
S bacteria can transform R bacteria, making them S
Chapter 16
The Molecular Basis of Inheritance
Avery (1928)
S bacteria can transform R bacteria, making them S.
Even heat-killed S bacteria can transform R bacteria.
Chapter 16
The Molecular Basis of Inheritance
Hershey & Chase (1952)
Chapter 16
The Molecular Basis of Inheritance
Hershey & Chase (1952)
Grew phage viruses with radioactive sulfur or phosphorus
Chapter 16
The Molecular Basis of Inheritance
Hershey & Chase (1952)
Grew phage viruses with radioactive sulfur or phosphorus.
Allowed viruses to infect cells.
Chapter 16
The Molecular Basis of Inheritance
Hershey & Chase (1952)
Separated infected cells from empty virus husks
Chapter 16
The Molecular Basis of Inheritance
Hershey & Chase (1952)
Separated infected cells from empty virus husks.
Sulfur stayed with husks,
phosphorus entered cells.
Chapter 16
The Molecular Basis of Inheritance
Watson, Crick, & Franklin (1953)
Chapter 16
The Molecular Basis of Inheritance
Watson, Crick, & Franklin (1953)
Worked out the double helix structure.
Chapter 16
The Molecular Basis of Inheritance
Meselson-Stahl (1950’s)
Chapter 16
The Molecular Basis of Inheritance
Meselson-Stahl (1950’s)
Cultured DNA with heavy nitrogen, then centrifuged it to find its density.
Chapter 16
The Molecular Basis of Inheritance
Meselson-Stahl (1950’s)
conservative
Chapter 16
The Molecular Basis of Inheritance
Meselson-Stahl (1950’s)
conservative
Chapter 16
The Molecular Basis of Inheritance
Meselson-Stahl (1950’s)
conservative
Chapter 16
The Molecular Basis of Inheritance
Meselson-Stahl (1950’s)
semi-conservative
Chapter 16
The Molecular Basis of Inheritance
Meselson-Stahl (1950’s)
semi-conservative
Chapter 16
The Molecular Basis of Inheritance
Meselson-Stahl (1950’s)
semi-conservative
Chapter 16
The Molecular Basis of Inheritance
Meselson-Stahl (1950’s)
dispersive
Chapter 16
The Molecular Basis of Inheritance
Meselson-Stahl (1950’s)
dispersive
Chapter 16
The Molecular Basis of Inheritance
Meselson-Stahl (1950’s)
dispersive
Chapter 16
The Molecular Basis of Inheritance
Meselson-Stahl (1950’s)
conservative
Chapter 16
The Molecular Basis of Inheritance
Meselson-Stahl (1950’s)
conservative
Chapter 16
The Molecular Basis of Inheritance
Meselson-Stahl (1950’s)
conservative
Chapter 16
The Molecular Basis of Inheritance
Meselson-Stahl (1950’s)
conservative
Chapter 16
The Molecular Basis of Inheritance
Meselson-Stahl (1950’s)
conservative
Chapter 16
The Molecular Basis of Inheritance
Meselson-Stahl (1950’s)
conservative
Chapter 16
The Molecular Basis of Inheritance
Meselson-Stahl (1950’s)
semi-conservative
Chapter 16
The Molecular Basis of Inheritance
Meselson-Stahl (1950’s)
semi-conservative
Chapter 16
The Molecular Basis of Inheritance
Meselson-Stahl (1950’s)
semi-conservative
Chapter 16
The Molecular Basis of Inheritance
Meselson-Stahl (1950’s)
semi-conservative
Chapter 16
The Molecular Basis of Inheritance
Meselson-Stahl (1950’s)
semi-conservative
Chapter 16
The Molecular Basis of Inheritance
Meselson-Stahl (1950’s)
dispersive
Chapter 16
The Molecular Basis of Inheritance
Meselson-Stahl (1950’s)
dispersive
Chapter 16
The Molecular Basis of Inheritance
Meselson-Stahl (1950’s)
dispersive
Chapter 16
The Molecular Basis of Inheritance
Meselson-Stahl (1950’s)
dispersive
Chapter 16
The Molecular Basis of Inheritance
Meselson-Stahl (1950’s)
dispersive
Chapter 16
The Molecular Basis of Inheritance
Meselson-Stahl (1950’s)
So what really happened?
Chapter 16
The Molecular Basis of Inheritance
Meselson-Stahl (1950’s)
So what really happened?
Chapter 16
The Molecular Basis of Inheritance
1st replication
→
Meselson-Stahl (1950’s)
So what really happened?
Chapter 16
The Molecular Basis of Inheritance
1st replication
→
Meselson-Stahl (1950’s)
So what really happened?
Chapter 16
The Molecular Basis of Inheritance
1st replication
→
2nd replication
→
Meselson-Stahl (1950’s)
So what really happened?
Chapter 16
The Molecular Basis of Inheritance
1st replication
→
2nd replication
→
A large team of enzymes carries out DNA replication
Chapter 16
The Molecular Basis of Inheritance
A large team of enzymes carries out DNA replication
1. Replication begins at origins of replication.
Chapter 16
The Molecular Basis of Inheritance
A large team of enzymes carries out DNA replication
2. A primer (short strand of RNA) is attached to DNA.
Chapter 16
The Molecular Basis of Inheritance
A large team of enzymes carries out DNA replication
3. Y-shaped replication forks form at opposite ends of a replication bubble.
Chapter 16
The Molecular Basis of Inheritance
A large team of enzymes carries out DNA replication
4. DNA polymerases work in the 5’ → 3’ direction.
Chapter 16
The Molecular Basis of Inheritance
A large team of enzymes carries out DNA replication
5. Synthesis produces a continuous leading strand and Okazaki fragments on the lagging strand.
Chapter 16
The Molecular Basis of Inheritance
A large team of enzymes carries out DNA replication
6. Okazaki fragments are joined together by DNA ligase.
Chapter 16
The Molecular Basis of Inheritance
A large team of enzymes carries out DNA replication
7. DNA polymerase proofreads new DNA and corrects errors in pairing.
Chapter 16
The Molecular Basis of Inheritance
A large team of enzymes carries out DNA replication
8. In excision repair, enzymes can cut out and replace damaged DNA.
Chapter 16
The Molecular Basis of Inheritance
A large team of enzymes carries out DNA replication
9. Telomeres (ends of DNA) get shorter with each replication.
Chapter 16
The Molecular Basis of Inheritance
A large team of enzymes carries out DNA replication
10. Telomerase can extend the ends.
.
Chapter 16
The Molecular Basis of Inheritance
