DNA and Protein Synthesis

1
DNA and Protein Synthesis
2
What is DNA?

• Contains the genetic information for making all
  the proteins in the cell

3
In the Beginning..

• The world of science debated on what the genetic
  material was
• Some thought it was protein
• Others believed it was DNA

4
Evidence for a Genetic Factor

• 1928 Frederick Griffiths Transforming Factor
  Experiment

• Conclusion Something from Heat-treated
  Strain 1 transformed Strain 2 to become deadly

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DNA is Proven to be that Genetic Factor

• 1944 Oswald Avery and colleagues focused on two
  of the genetic factor candidates protein and
  DNA
• Repeated Griffiths experiment, but with a
  modification

?
?
Proteases
Mouse dies
?
?
DNases
Mouse lives
Conclusion DNA is the transforming, thus
genetic material
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Avery Questioned In the Scientific Community
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Final Proof that DNA is the Genetic Material

• 1952 Hershey-Chase Experiment
• Virus DNA (inside) protein (outside)

Conclusion DNA was the genetic material due to
viruses passing on DNA for reproduction
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The DNA Twist

• DNA is a double helix
• Every 10 nucleotides there is a 360 degree
  rotation
• The structure of DNA is accredited to James
  Watson, Francis Crick and Rosalind Franklin

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Frame of Reference
Where is the DNA located in eukaryotes?
Prokaryotes?
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The Structure of DNA

• DNA deoxyribonucleic acid
• DNA is a polymer built up from monomers
• Monomers are called nucleotides

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The Structure of DNA Continued

• Phosphate Group provides the backbone of
  DNA? 5 end (5 prime end)
• Sugar called a deoxyribose also part of the
  DNA backbone? 3 end (3 prime end)
• Backbone of DNA called the sugar-phosphate
  backbone

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Nitrogenous Bases of DNA

• Nitrogenous bases of DNA
• Two Types
• Pyrimidines ? Thymine (T)
• ? Cytosine (C)
• Purines ? Adenine (A)
• ? Guanine (G)
• Purines are double ringed, pyrimidines are
  single ringed

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Pairing of Bases

• In DNA G hydrogen bonds with C
• T hydrogen bonds with A

G
C
C
A
T
G
T
A
C
G
T
A
T
C G G T A C A T G
C A T A
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Chargaffs Rule

• 1950 Erwin Chargaff discovered
• A approximately equals T
• G approximately equals C
• This is true for all species!
• In humans
• A 30.9 and T 29.4
• G 19.9 and C 19.8

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Lets Put the Structure Together

• Notice the following
• 5 and 3 ends
• AT and GC
• Hydrogen bond numbers
• Sugar-phosphate backbone
• Two strands are antiparallel