DNA, Transcription, Translation

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DNA
Structure

• Chapter 8

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• http//youtu.be/zwibgNGe4aY
• Be ready to write down 3 things you remember from
  the video!

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DNA Stands for

• DNA Deoxyribonucleic acid
• Very large biomolecule made up of nucleotides
• Called the blueprints of life because it
  contains genetic information for the construction
  of proteins.

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• Floats freely in the cytoplasm of prokaryotes
• Protected in the nucleus of eukaryotes

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• Nucleotide DNA subunit (monomer) made up of 3
  parts
• Deoxyribose sugar
• Phosphate group
• Nitrogenous base

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DNA Structure

• Made of 2 nucleotide chains that wrap around each
  other to form a double helix (looks like a spiral
  staircase)
• The sides Alternating Sugar, phosphate, sugar,
  phosphate
• The middle Nitrogen bases paired together.

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Scientists Involved in Discovery of DNA

• James Watson Francis Crick
• developed double helix model of DNA
• other scientists working on finding the
  structure
• Rosalind Franklin
• Maurice Wilkins
• Linus Pauling

Wilkins
Pauling
Franklin
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1953 article in Nature
Watson and Crick
Watson
Crick
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Nitrogenous Bases

• There are 2 groups of nitrogenous bases purines
  and pyrimidines
• Purines Made up of two rings of carbon and
  nitrogen
• Adenine (A), Guanine (G)

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• Pyrimidines Bases that have one ring of carbon
  and nitrogen
• Thymine (T), Cytosine (C)

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Identifying the structure
Purine purine too wide
Pyrimidine pyrimidine too narrow
Purine pyrimidine width consistent with X-ray
data
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Conclusion Purine (A, G) pair with Pyrimidine
(C, T)
Adenine (A)
Thymine (T)
Cytosine (C)
Guanine (G)
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Chargaffs Base Pairing Rules

• DNA composition Chargaffs rules
• varies from species to species
• all 4 bases not in equal quantity
• bases present in characteristic ratio
• humans
• A 30.9
• T 29.4
• G 19.9
• C 19.8

1947
Thats interesting!What do you notice?
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Chargaffs Base Pairing Rules

• A pairs with T
• Always Together

• G pairs with C
• Get Closer

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Summary

• Summarize what we just talked about by
• Come up with 3 alternate titles for our notes
• OR Drawing a picture to remember base pairing
• OR Writing about how DNA structure is like a
  staircase