19. Looking at your gels
• What do you notice about the “banding
patterns” in each lane in your gels?
• What is different about the “pools” of DNA
that you loaded into each well?
21. Look at you gel again
• Estimate the size of the DNA fragment(s)
in the pMAP lane.
• Does the relationship between the
distance migrated and DNA fragment size
appear to be a linear relationship?
45. Fig. 20-3-2
Restriction site
DNA
Sticky end
Restriction enzyme
cuts sugar-phosphate
backbones.
5′
3′
3′
5′
1
DNA fragment added
from another molecule
cut by same enzyme.
Base pairing occurs.
2
One possible combination
46. Fig. 20-3-3
Restriction site
DNA
Sticky end
Restriction enzyme
cuts sugar-phosphate
backbones.
5′
3′
3′
5′
1
One possible combination
Recombinant DNA molecule
DNA ligase
seals strands.
3
DNA fragment added
from another molecule
cut by same enzyme.
Base pairing occurs.
2
47. Fig. 20-9a
Mixture of
DNA mol-
ecules of
different
sizes
Power
source
Longer
molecules
Shorter
molecules
Gel
AnodeCathode
TECHNIQUE
1
2
Power
source
– +
+–
50. Fig. 20-10
Normal
allele
Sickle-cell
allele
Large
fragment
(b) Electrophoresis of restriction fragments
from normal and sickle-cell alleles
201 bp
175 bp
376 bp
(a) DdeI restriction sites in normal and
sickle-cell alleles of β-globin gene
Normal β-globin allele
Sickle-cell mutant β-globin allele
DdeI
Large fragment
Large fragment
376 bp
201 bp175 bp
DdeIDdeI
DdeI DdeI DdeI DdeI
64. Development of Model
• One Gene – One Enzyme (Nobel 1958)
• One Gene – One Polypeptide
– Non enzyme proteins (keratin, insulin)
– Hb – multimeric protein.
• Issues:
– Alternate splicing
– RNA coding genes.
– Non-coding regions
79. Fig. 18-6
DNA
Signal
Gene
NUCLEUS
Chromatin
modification
Chromatin
Gene available
for transcription
Exon
Intron
Tail
RNA
Cap
RNA processing
Primary transcript
mRNA in nucleus
Transport to cytoplasm
mRNA in cytoplasm
Translation
CYTOPLASM
Degradation
of mRNA
Protein processing
Polypeptide
Active protein
Cellular function
Transport to cellular
destination
Degradation
of protein
Transcription
81. Fig. 18-8-1
Enhancer
(distal control elements)
Proximal
control elements
Poly-A signal
sequence
Termination
region
Downstream
Promoter
Upstream
DNA
ExonExon ExonIntron Intron
82. Fig. 18-8-2
Enhancer
(distal control elements)
Proximal
control elements
Poly-A signal
sequence
Termination
region
Downstream
Promoter
Upstream
DNA
Exon Exon ExonIntronIntron
Cleaved 3′ end
of primary
transcript
Primary RNA
transcript
Poly-A
signal
Transcription
5′
ExonExon ExonIntron Intron
83. Fig. 18-8-3
Enhancer
(distal control elements)
Proximal
control elements
Poly-A signal
sequence
Termination
region
Downstream
Promoter
Upstream
DNA
ExonExon ExonIntron Intron
Exon Exon ExonIntronIntron
Cleaved 3′ end
of primary
transcript
Primary RNA
transcript
Poly-A
signal
Transcription
5′
RNA processing
Intron RNA
Coding segment
mRNA
5′ Cap 5′ UTR
Start
codon
Stop
codon 3′ UTR Poly-A
tail
3′
89. Fig. 18-2
Regulation
of gene
expression
trpE gene
trpD gene
trpC gene
trpB gene
trpA gene
(b) Regulation of enzyme
production
(a) Regulation of enzyme
activity
Enzyme 1
Enzyme 2
Enzyme 3
Tryptophan
Precursor
Feedback
inhibition
90. Fig. 18-3a
Polypeptide subunits that make up
enzymes for tryptophan synthesis
(a) Tryptophan absent, repressor inactive, operon on
DNA
mRNA 5′
Protein Inactive
repressor
RNA
polymerase
Regulatory
gene
Promoter Promoter
trp operon
Genes of operon
Operator
Stop codonStart codon
mRNA
trpA
5′
3′
trpR trpE trpD trpC trpB
ABCDE
91. Fig. 18-3b-1
(b) Tryptophan present, repressor active, operon off
Tryptophan
(corepressor)
No RNA made
Active
repressor
mRNA
Protein
DNA
92. Fig. 18-3b-2
(b) Tryptophan present, repressor active, operon off
Tryptophan
(corepressor)
No RNA made
Active
repressor
mRNA
Protein
DNA
93. Fig. 18-4a
(a) Lactose absent, repressor active, operon off
DNA
Protein
Active
repressor
RNA
polymerase
Regulatory
gene
Promoter
Operato
r
mRNA
5′
3′
No
RNA
made
lacI lacZ
112. Encode
The Encyclopedia of DNA Elements
http://www.youtube.com/watch?v=TwXXgEz9o4w&feature=player_d
http://www.youtube.com/watch?v=Y3V2thsJ1Wc&feature=player_de
139. Fig. 20-12
DNA
(template strand)
TECHNIQUE
RESULTS
DNA (template
strand)
DNA
polymerase
Primer Deoxyribonucleotides
Shortest
Dideoxyribonucleotides
(fluorescently tagged)
Labeled strands
Longest
Shortest labeled strand
Longest labeled strand
Laser
Direction
of movement
of strands
Detector
Last base
of longest
labeled
strand
Last base
of shortest
labeled
strand
dATP
dCTP
dTTP
dGTP
ddATP
ddCTP
ddTTP
ddGTP
159. Two Opposing Theories
• Multiregional Theory
– Parallel evolution
• Displacement Theory
– Out of Africa theory
http://news.bbc.co.uk/
160.
161. Neandertal Genome Study Reveals
That We Have a Little Caveman in
Us
Svante Paabo
Europeans and Asians share 1% to 4% of
their nuclear DNA with Neandertals. But
Africans do not