Genetics of Cancer

Fig Signaling cell DNA Nucleus Transcription factor (activated) Signaling molecule Plasma membrane Receptor protein Relay proteins Transcription mRNA New protein Translation Target cell Signal Transduction: Way in which a cell can respond to signals from its environment Results in a change in which genes are expressed (turned on)

Fig a Growth factor Protein that Stimulates cell division Translation Nucleus DNA Target cell Normal product of ras gene Receptor Relay proteins Transcription factor (activated) Hyperactive relay protein (product of ras oncogene) issues signals on its own Transcription Ras is an oncogene (cancer gene) the normal form of the gene is a proto-oncogene Oncogenes STIMULATE cell division

Fig b Growth-inhibiting factor Protein that inhibits cell division Translation Normal product of p53 gene Receptor Relay proteins Transcription factor (activated) Nonfunctional transcription factor (product of faulty p53 tumor-suppressor gene) cannot trigger transcription Transcription Protein absent (cell division not inhibited) Normal tumor- suppressor genes prohibit cell division

5 Progression of Colon Cancer

Both alleles of BRCA1 or both alleles of BRCA2 must be mutant for cancer to develop. Why would in follow a dominant inheritance pattern? A tissue comprised of billions of cells heterozygous for BRCA1 or BRCA2 7 Your (my) probability of winning the lottery is very small. The probability that someone will win it is very large.

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???

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 Crime scene DNA isolated 1 Suspect 1Suspect 2 DNA of selected markers amplified 2 Amplified DNA compared 3

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…