DNA History

1

• DNA History
• (In brief)

2

• Frederick Griffith (1928) worked with mice and
  pneumonia bacteria determined characteristics of
  one strain could be passed to another
  transformation

3

• Rosalind Franklin (early 1950s)
• - uses x-rays to determine structure
• - DNA is twisted
• - double stranded
• molecules within DNA were evenly spaced

4

• James Watson and Francis Crick (1953)
• given credit for determining the overall shape of
  DNA
• created models made of clay, wire, etc.
• 1962 Nobel Prize Winners

5

• What is DNA?
• DNA deoxyribonucleic acid
• genetic blue print molecule of heredity enables
  us to pass genes from one generation to the next
• found only in the nucleus of cells contains
  instructions for assembling the proteins of the
  cell

6

• Structure of a DNA Molecule
• The overall shape of DNA is a double helix
  double stranded and spiral shaped. (twisted
  ladder)
• DNA is a polymer made of many nucleotide monomers

7

• Each nucleotide of DNA consists of a
• 1. phosphate group
• 2. 5 carbon deoxyribose sugar backbone
  of DNA ladder
• 3. a nitrogenous base rungs of the ladder

many nucleotides bonded together to make a DNA
molecule 1 nucleotide is circled
one nucleotide
8

• There are 4 nitrogenous bases in DNA adenine
  (A), guanine (G), cytosine (C), and thymine (T).
• The structure of the molecules of adenine and
  guanine contains 2 rings purines.
• The structure of the molecules of cytosine and
  thymine contains 1 ring pyrimidines.

pyrimidines
purines
9

• In a DNA molecule adenine (A) always bonds to
  thymine (T) cytosine (C), always bonds to
  guanine (G)
• The nitrogenous bases are held together by
  hydrogen bonds

10

• If this is the sequence of nitrogen bases on one
  strand of DNA,what would be the complementary
  base pairs on the other strand of the DNA
  molecule?
• A C G A A T G C T A

11

• A C G A A T G C T A
• T G C T T A C G A T

12
DNA (Molecular Image)
Key Hydrogen bones Purines pyrimidines

• 
  
• Deoxyribose sugar

Phosphate Groups
13

• What is a gene?
• a gene is a segment of a DNA molecule
• a gene codes for a protein, which in turn codes
  for a trait (skin tone, eye color.,etc)
• The average gene is 10,000 to 15,000 bases long.

14

• How is DNA stored in our cells?
• Very tightly coiled into chromosomes

15
Just how much DNA/ genetic information is in our
cells?

• If all the DNA in your body was put end to end,
  it would reach to the sun and back over 600
  times.
• (93 million miles - one way)

16

• If all three billion letters in the human genome
  were stacked one millimeter apart, they would
  reach a height 7,000 times the height of the
  Empire State Building.

17

• If you unwrap all the DNA you have in all your
  cells, you could reach the moon 6000 times!
• Over 99 of our DNA sequence is the same as other
  humans.