cystic fibrosis (cf) - gene location

Cystic Fibrosis (CF) - gene location

Cystic Fibrosis (CF): Molecular defect

Cystic Fibrosis (CF): One gene may lead to many phenotypic effects

Cystic Fibrosis lungs

Normal lung Lung from a CF patient, showing extensive destruction as a result of obstruction and infection

Normal pancreasCF Pancreas showing infiltration of fat and fibrotic lesions

Cystic Fibrosis Pancreas

Tay Sachs

• Defective enzyme that breaks down a particular fatty substance

ALPHA GLOBIN ALPHA GLOBIN

BETA GLOBIN BETA GLOBIN

Sickle cell mutation

Heme

Iron atom

Heme

Iron atom

Sickle cell mutation

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The hemoglobin tetramer

Normal and Sickled Cell

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Sickle Cell Anemia (AR)

Aggregation of hemoglobin molecules. Mutant hemoglobin molecules in red cells stack to form rodlike structures, which causes the red cells to deform.

The Genetics of Cancer

Fig. 11-12Signaling cell

DNA

Nucleus

Transcriptionfactor(activated)

Signaling molecule Plasma

membraneReceptorprotein

Relayproteins

TranscriptionmRNANewprotein

Translation

Target cell

2

1

3

4

5

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Signal Transduction:

How a cell can respond to signals from its environment

Results in a change in which genes are expressed (turned on)

Fig. 11-20aGrowth factor

Protein thatStimulatescell division

Translation

Nucleus

DNA

Target cell

Normal productof ras gene

Receptor

Relayproteins

Transcriptionfactor(activated)

Hyperactiverelay protein(product ofras oncogene)issues signalson its own

Transcription

Ras is an oncogene (cancer gene) the normal form of the gene is called a proto-oncogene

Oncogenes STIMULATE cell division

Fig. 11-18a

Mutation withinthe gene

Hyperactivegrowth-stimulatingprotein in normalamount

Proto-oncogene DNA

Multiple copiesof the gene

Gene moved tonew DNA locus,

under new controls

Oncogene New promoter

Normal growth-stimulatingprotein in excess

Normal growth-stimulatingprotein in excess

Fig. 11-20bGrowth-inhibiting factor

Protein thatinhibitscell division

Translation

Normal productof p53 gene

Receptor

Relayproteins

Transcriptionfactor(activated)

Nonfunctional transcriptionfactor (product of faulty p53tumor-suppressor gene) cannot trigger transcription

Transcription

Protein absent(cell divisionnot inhibited)

Normal tumor-suppressor genes prohibit cell division

Fig. 11-18b

Mutated tumor-suppressor geneTumor-suppressor gene

Defective,nonfunctioningprotein

Normalgrowth-inhibitingprotein

Cell divisionunder control

Cell division notunder control

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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

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