Download Ch12 DNA

DNA
The Discovery of DNA
The Discovery of DNA
Griffith and Transformation:
Transformation: One strain of bacteria (harmless)
had changed into disease-causing strain
Meant gene with info was transferred from heatkilled into live cells
The Discovery of DNA
Avery tried to break down the heat-killed
bacteria with enzyme that would usually break
up DNA, but it didn’t
Avery concluded that DNA is nucleic acid that
stores and transmits the genetic info from 1
generation to another
The Discovery of DNA
Hershey and Chase Experiment:
Don’t
Studied bacteriophages (viruses) “bacteria eaters”
copy
made of DNA/RNA and protein coat
Don’t
Bacteriophages inject DNA into bacteria, the viral
copy
genes act to produce many new bacteriophages and
burst of out cell
Conclusion: using radioactive markers, genetic
material of bacteriophage was DNA not protein
The Structure of DNA
DNA is molecule made of nucleotides
Nucleotides made of 3 parts:
5 Carbon sugar called Deoxyribose
Phosphate group
Nitrogenous Base
Point out nucleotides for DNA
activity on papers
The Structure of DNA
4 Nitrogenous Bases:
Purines (2 rings)
Adenine
Guanine
Pyrimidines (1 ring)
Cytosine
Thymine
The Double Helix
Watson and Crick’s model of DNA
was a double helix, where two
strands were wound around each
other
Remember:
Tits=Ass
Good=Candy
They discovered that hydrogen
bonds could form between certain
nitrogenous bases and provide
enough force to hold 2 strands
together
Base-pairing:
Andenine=Thymine
Guanine=Cytosine
DNA vs RNA
DNA (Deoxyribose Nucleic Acid)
Double Stranded
Nucleotides include:
Adenine, Guanine, Cytosine, Thymine
DNA is “read” to make RNA
RNA (RiboNucleic Acid)
Single Stranded
Nucleotides include:
Adenine, Guanine, Cytosine, Uracil
RNA is “read” to make proteins
Elements
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