Chapter 11- Inheritance and Genetic Engineering

A summary of the 11th Chapter- Inheritance and Genetic Engineering of the AQA GCSE Human Health and Physiology textbook

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  • Created by: R_Hall
  • Created on: 18-06-12 11:30

11.1 Inheritance of characteristics

  • As you inherit one set of chromosomes from each parent, you inherit half of your genes from each parent
  • Visible changes in chromosomes are called chromosome mutations. Loss of chromosomes is fatal, and duplication can lead to disorders
  • A gene works as a chemical code instructing the cell to produce a particular protein. Alleles are versions of genes that you inherit from parents
  • Accidental changes in DNA structure are gene mutations. A gene mutation can result in the loss of an enzyme or structural protein. If reactions do not take place, a genetic disorder may occur
  • Cystic fibrosis is a recessive (need two copies of allele) genetic disorder where a person produces sticky, thick mucus
  • Huntington's disease is a dominant (need only one copy of allele) genetic disorder that causes degeneration of brain cells
  • Physical characteristics are called the phenotype and the genes you have are the genotype
  • If both alleles are the same, the genotype is homozygous (one type of gene). If the alleles are different, the genotype is heterozygous
  • Sex-linked genes are situated on the X chromosome, so can cause males to inherit sex-linked disorders
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11.2 Genetic engineering

  • Scientists are finding ways of correcting faulty genes to cure genetic disorders. The main problem is transferring the non-faulty gene to the appropriate cells; in some cases, a virus is used as a carrier
  • Gene therapy for CF is hard as the lungs are designed to remove particles and the person with CF produces sticky mucus. An alternative is to screen embryos for CF genes, and replace with normal genes
  • Doctors treat leukaemia with donor bone marrow to replace the blood cells that die . Bone marrow cells are stem cells, which divide and change into other cells- they differentiate.
  • During treatment, bone marrow cells are killed, so donor cells replace them
  • In some cases, the person's own bone marrow is removed, treated to kill the cancer cells and returned, lowering risk of rejection
  • Stem cells are also hoped to be used to replace damaged tissues with cells cultured in a lab
  • Stem cells can also be collected from umbilical cord blood
  • Human insulin can be made if enzymes are used to cut insulin genes from cells and a plasmid from a bacterium. The gene and plasmid are put together, inserted into a bacterium and then fermented to produce insulin
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