DNA

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DNA Structure
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• Where do we get our DNA from?

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Structure of DNA

• Discovered in 1950s by Rosalind Franklin using
  X-ray diffraction.
• Double Helix term coined by Watson and Crick in
  the 1950s as well.

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• DNA is arranged into a ladder-like structure
  called a Double Helix.

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DNA Structure

• A molecule of DNA is made up of millions of tiny
  subunits called Nucleotides.
• Each nucleotide consists of
• Phosphate group
• Pentose sugar
• Nitrogenous base

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Nucleotides
Phosphate
Nitrogenous Base
Pentose Sugar
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Nucleotides

• The phosphate and sugar form the backbone of the
  DNA molecule, whereas the bases form the rungs.
• There are four types of nitrogenous bases.

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Nucleotides (Practice)
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Nucleotides

• Each base will only bond with one other specific
  base.
• Adenine (A)
• Thymine (T)
• Cytosine (C)
• Guanine (G)

Form a base pair.
Form a base pair.
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DNA Structure

• Because of this complementary base pairing,
• the order of the bases in one strand determines
• the order of the bases in the other strand.
• BASE PAIRING IS ALWAYS EQUAL!!!!
• (Ex 25 A25 T)

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What do these have in common?
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• ALL organisms have the SAME components that make
  up their DNA!
• Think about the Alphabet...

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DNA Structure

• A gene is a section of DNA that codes for a
  protein.
• Each unique gene has a unique sequence of bases.
• This unique sequence of bases will code for the
  production of a unique protein.
• It is these proteins and combination of proteins
  that give us a unique phenotype.

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DNA
Gene
Protein
Trait
The purpose of DNA is to help the ribosomes make
PROTEIN!!!!
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Write this down..

• How are our traits carried on our DNA?

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• DNA is copied during a process called
  replication!
• What phase of the cell cycle does DNA replication
  occur?
• Replication resultsone new strand one original
  strand

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• http//www.youtube.com/watch?v5_vzY7H9GYkfeature
  related