The document summarizes several key concepts in genetics: 1) Gene maps can be constructed using recombination frequencies to determine the relative distances between genes. 2) Griffith's transformation experiment provided evidence that genetic material can be transferred between bacteria, supporting the idea that genetic information is carried by a transferable molecule. 3) The Hershey-Chase experiment used radioisotope labeling to show that viral DNA, not protein, enters the host cell, demonstrating that DNA carries the genetic information of viruses.

1. 11-20-09 Notes
Mendelian Genetics Continued . . .
Using recombination frequencies to construct a gene map
-Map unit => relative distance
Gene Maps
A-F 15%
D-F 5%
D-A 10%
F-C 8%
D-C 13%
**on exam**
Page 181 – Chapter 10
DNA as the Genetic Material
-The search for genetic material led to DNA
-Complimentary base pairing
Griffith Transformation Experiment
-Develop hypothesis that genetic information is carried on a transferable
molecule.
-Capsule in pneumonia virus molecule makes it dangerous, toxin causes
problems.
-Investigated whether pneumonia caused by live bacteria, or by related
toxin
-Heated live smooth strain bacteria break apart, internal molecules of DNA carry
capsule-making genes
Living smooth cells [control] -> mouse dies
Living rough cells [control] -> mouse healthy
Heat killed smooth cells [control] -> mouse healthy
Mixture of heat-killed smooth cells and living rough cells -> mouse dies
Live rough bacteria can transform into smooth strain bacteria by absorbing
genetic material.
Page 183
Virus: protein covering, DNA or RNA inside.
Attach selves to living host cell

2. -Viral DNA destroys host cell’s genes, and instructs it to copy virus cells and
proteins.
-Rhinovirus symptoms caused by damage of respiratory tract cells, causes
excess mucus production, headache, etc.
-Rearrangable polymer subunits. Information stored in sequence
-Proteins can be built to any length, 20 different types, can store various different
sequences of amino acids.
-Virus made of protein and DNA
-T2 Phages infecting bacterial cell
-Phage => Bacteria virus
-Virus injects DNA into host cell, DNA instructs cell to replicate
(virus replication)
-Phage parts accumulate and group together to form phages
-Cell ruptures, phages spill out and infect other cells
Hershey-Chase Experiment [1953]
-designed to determine which part of virus goes into host cell,
and which does not.
-Radio-labelled media – sulphur 35, phosphorous 32 –
radioactive isotopes.
-Labelled, locatable protein [sulphur]
-No sulphur in DNA, so DNA is not radio-labelled.
-Two parallel experiments.
-Phage protein was labelled, DNA was not
-Phage DNA labelled, outer coat was not
-Radio labelled phages were allowed to reproduce and
injected molecule into host cell, Hershey and Chase
blended cells and broke them open, and mixed cells.
-Sulphur 35 phages were found outside, radioactive
DNA found inside host cell.
-Proved DNA carried genetic information, as host cell behaved
differently when cell parts were mixed up.