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Genetics of Cancer
Fig. 11-12
Signaling cell
Signal
Transduction:
Signaling
molecule
Plasma
Receptor membrane
protein
1
2
3
Way in which a cell
can respond to
signals from its
environment
Results in a change
in which genes are
expressed (turned on)
Target cell
Relay
proteins
Transcription
factor
(activated)
4
Nucleus
DNA
5
mRNA Transcription
New
protein
6
Translation
Fig. 11-20a
Growth factor
Receptor
Target cell
Hyperactive
relay protein
(product of
ras oncogene)
issues signals
on its own
Normal product
of ras gene
Relay
proteins
Oncogenes
STIMULATE
cell division
Transcription
factor
(activated)
DNA
Nucleus
Protein that
Stimulates
cell division
Transcription
Translation
Ras is an
oncogene
(cancer gene)
the normal form
of the gene is a
proto-oncogene
Fig. 11-20b
Growth-inhibiting
factor
Receptor
Relay
proteins
Transcription
factor
(activated)
Normal tumorsuppressor genes
prohibit cell division
Nonfunctional transcription
factor (product of faulty p53
tumor-suppressor gene)
cannot trigger
transcription
Normal product
of p53 gene
Transcription
Protein that
inhibits
cell division
Translation
Protein absent
(cell division
not inhibited)
Progression of Colon Cancer
5
A tissue comprised of billions of cells heterozygous for BRCA1 or BRCA2
Both alleles of
BRCA1 or both
alleles of
BRCA2 must
be mutant for
cancer to
develop.
Why would in
follow a dominant
inheritance
pattern?
Your (my) probability of winning the lottery is very small. The
probability that someone will win it is very large.
7
One of the key tools in DNA
technology is the restriction enzyme
Where do these restriction
enzymes come from????
What is their natural function???
How can we use them???
https://www.dnalc.org/view/15255-Producing-human-insulinusing-recombinant-DNA-Walter-Gilbert.html
https://www.dnalc.org/view/15476-Mechanism-ofRecombination-3D-animation-with-with-basic-narration.html
Use restriction enzymes to break
DNA into manageable sized pieces
that we can separate using the
technique of gel electrophoresis
How is this done
What can we tell from this?
• It can be used to compare the DNA from
different organisms
• Used to detect disease alleles
• Used to “match” DNA samples
– Determine parentage
– Crime scene forensics
Detecting disease alleles
Fig. 12-11
Crime scene
1 DNA isolated
2 DNA of selected
markers amplified
3 Amplified DNA
compared
Suspect 1
Suspect 2
Recombinant DNA
• DNA from 2 sources combined
– Can be used to clone genes
– Used to produce a particular protein
How is this recombinant DNA made?
GMOs
• Research 3 GMOs
– Type of organism
– What is modified (what gene)?
– What is the benefit
• Your thoughts…