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Gel electrophoresis
DNA sequencing
Central Dogma
DNA is the genetic material
within the nucleus.
Replication
The process of replication
creates new copies of DNA.
The process of transcription
creates an RNA using
DNA information.
DNA
Transcription
RNA
Nucleus
The process of translation
creates a protein using
RNA information.
Translation
Protein
Cytoplasm
DNA Double Helix-Held Together with
H-Bonds
Base Pairs Double Helix
Three Components of DNA Structure
base: thymine
(pyrimidine)
monophosphate
sugar: 2’-deoxyribose

5’
4’
3’
(5’ to 3’)
1’
2’
3’ linkage
base:adenine
(purine)
5’ linkage
no 2’-hydroxyl
Pyrimidines used in Base Pairs,
DNA
6-membered rings only
Purines used in Base Pairs, DNA
Fused 5 and 6 member rings
DNA Base Pairing
A-T pairing
2 H-Bonds
G-C pairing
3 H-bonds
A-T and G-C Base Pairs Hold the
DNA helices together
A-T and G-C Base Pairs Hold the
DNA helices together
A-T and G-C Base Pairs Hold the
DNA helices together
A-T and G-C Base Pairs Hold the
DNA helices together
A-T and G-C Base Pairs Hold the
DNA helices together
Transcription
• The new RNA molecule is formed by incorporating
• nucleotides that are complementary to the
template strand.
DNA coding strand
5’
3’
DNA
G T C A T T C G G
3’
G U C A U U C G G
3’
C A G T A A G C C
5’
DNA template strand
5’
RNA
# of strands
kind of sugar
bases used
RNA Polymerase is the Enzyme that Catalyzes
Transcription of DNA Information to RNA
DNA (Blue)
Newly Synthesized
RNA (Red)
Bridge Helix Moves
DNA through
Polymerase during
RNA Synthesis
(Green)
Active Site Metal
(Pink)
Transcription
• The new RNA molecule is formed by incorporating
• nucleotides that are complementary to the
template strand.
DNA coding strand
5’
3’
DNA
G T C A T T C G G
3’
G U C A U U C G G
3’
C A G T A A G C C
5’
DNA template strand
5’
RNA
Translation
• The process of reading the RNA sequence of an
mRNA and creating the amino acid sequence of a
protein is called translation.
DNA
template
DNA
Transcription
T
T
C
A
G
T
C
A
G
A
A
G
U
C
A
G
U
C
strand
Messenger
RNA
mRNA
Codon
Codon
Codon
Translation
Protein
Lysine
Serine
Valine
Polypeptide
(amino acid
sequence)
Genetic information written in codons is
translated into amino acid sequences
• The “words” of the DNA “language” are
triplets of bases called codons
– 3 bases or nucleotides make one
codon
– Each codon specifies an amino acid
– The codons in a gene specify the amino
acid sequence of a polypeptide
The genetic code is the Rosetta stone of life
• Virtually all
organisms
share the same
genetic code
• All organisms
use the same
20 aa
• Each codon
specifies a
particular aa
Figure 10.8A
• Tryptophan and
Methionine have
only 1 codon each
• All the rest have
more than one
• AUG has a dual
function
• 3 stop codons that
code for termination
of protein synthesis
• Redundancy in the
code but no
ambiguity
Figure 10.8A
http://www.dnalc.org/ddnalc/resources/sangerseq.html
http://www.shsu.edu/~chm_tgc/sounds/flashfiles/GE.swf
Shotgun sequencing: assembly of random sequence fragments