DNA NOTES

1
DNA NOTES
2
DNAs Shape

• DNAs shape was discovered by 2 scientists in the
  1950s.
• Watson and Crick named the shape of DNA the
  Double Helix.
• DNA looks like a twisted ladder.

3
Building Blocks of DNA

• DNA is made of nucleotides.
• Nucleotides have 3 parts
• 5-carbon sugar called deoxyribose
• A phosphate group
• 1 of 4 nitrogenous bases
• Adenine (A), Guanine (G), Cytosine (C),
  Thymine (T)

4
Purines vs. Pyrimidines

• Two of the nitrogenous bases belong to a group of
  compounds known as Purines these are Adenine
  Guanine
• The other 2 nitrogenous bases belong to a group
  of compounds known as Pyrimidines these are
  Cytosine Thymine
• Purines have 2 rings in their structures and
  pyrmidines only have 1 ring
• Purines cant bond to other purines and
  pyrimidines cant bond to other pyrimidines

5
Base Pairing

• The nitrogenous bases only make complementary
  bonds.
• Complementary means two things that fit or go
  together
• Example salt pepper, PB J
• The bases pair up complementary also A-T G-C

6
Makeup of DNA

• Sides of DNA ladder are made up of Sugar
  phosphate group
• The sides are held together by strong covalent
  bonds
• Middle (rungs) of DNA ladder are made up of
  Nitrogenous bases
• The middle is held together by weak bonds called
  Hydrogen bonds

7
Sample DNA Strand
Sides Made of Sugar Phosphate Bonds Strong,
COVALENT
Rungs (Middle) Made of Nitrogenous
bases Bonds Weak, HYDROGEN
8
DNA Strand

• Note that the sides of the DNA strand run in
  opposite directions of each other (one side is
  right side up and the other is upside down)
• Draw

5
3
3
5
9
Complementary Strands
10
DNA Simulation

• Make sure Biological Simulations CD is in the
  drive or use the website below to review DNA

http//learn.genetics.utah.edu/content/begin/dna/
Click on What is DNA