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B2.7 genetic disorders
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- 2. B2.7 Genetic disorders Inheriteddisorders: Polydactyl Cystic Fibrosis (CF) Huntington’s disease
- 3. You are theresult of two things... and Key words Gene Genetic diagrams Genetic disorders Inherited Dominant Recessive Alleles Polydactyl Cystic fibrosis Monohybrid crosses Homozygous Heterozygous Phenotype Genotype Stem cells Embryos
- 4. Polydactyl Polydactyly – havingextra fingers or toes – is caused by a dominant allele of a gene and can therefore be passed on by only one parent who has the disorder
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- 7. Polydactyl p p P PpPp p pp pp
- 8. Cystic Fibrosis This isa disorder of cell membranes. It is caused by a recessive allele so must be inherited from both parents. The parents may be carriers of the disorder without actually having the disorder themselves.
- 9. Cystic Fibrosis Digestive system Thicksticky mucus in pancreas prevents enzyme release. Food not digested properly. Respiratory System Thick sticky mucus blocks passageways in the lungs. Breathlessness and respiratory diseases.
- 10. The faulty alleleis recessive (f) An individual with one recessive allele is a carrier An individual with two recessive alleles has cystic fibrosis Cystic Fibrosis
- 11. F f F f Cystic Fibrosis Thefaulty allele is recessive (f) An individual with one recessive allele is a carrier An individual with two recessive alleles has cystic fibrosis
- 12. F f F FFFf f Ff ff Cystic Fibrosis The faulty allele is recessive (f) An individual with one recessive allele is a carrier An individual with two recessive alleles has cystic fibrosis
- 13. What is thechance of two carriers having a child with CF? F f F FF Ff f Ff ff Cystic Fibrosis The faulty allele is recessive (f) An individual with one recessive allele is a carrier An individual with two recessive alleles has cystic fibrosis
- 14. What is thechance of two carriers having a child with CF? F f F FF Ff f Ff ff Cystic Fibrosis The faulty allele is recessive (f) An individual with one recessive allele is a carrier An individual with two recessive alleles has cystic fibrosis 1 in 4 or 25% or 0.25
- 15. Symptoms Loss of musclecontrol Forgetfulness Loss of understanding Huntingdon’s Disease individual with one dominant alleles has Huntington's Disease Faulty allele is dominant
- 17. What can science doabout genetic disease? GENETIC TESTING • adults, fetuses or embryos • remove a cell • test for disease causing allele • adults may choose not to have children • termination of fetus with disease PRE-IMPLANTATION GENETIC DIAGNOSIS • fertilisation takes place in lab • remove a cell from 8 cell embryo • test for disease causing allele • only implant embryo without disease GENE THERAPY • could be used to cure genetic disease eg CF • make lots of copies of normal allele • put alleles into virus • virus 'infects' bone marrow cells • genetically modified cells placed back inside body
- 18. CLONING stem cells unspecialised cellscan become any type of cell could be used to treat human illness - 'theraputic cloning' some organisms clone themselves eg spider plants genetically identical differences caused by environment
- 19. Some of theissues... Should we test fetuses for genetic disorders? Are you worried about employers or insurance companies knowing your genetic information? Is it ethical to terminate a fetus? Is gene therapy playing God? Would you think so if it could cure you of a terminal illness? is cloning animals acceptable? How about humans? Why? why not?