b6 - inheritance

• Define meiosis

  A special type of cell division that happens in the reproductive organs to produce gametes.
• what do gametes contain?

  gametes contain half the number of chromosomes of a body cell (23 chromosomes). This is called haploids.
• order of size, largest to smallest. (cell, chromosomes, DNA, genes, nucleus, organism)

  organism, cell, nucleus, chromosomes, DNA, genes
• Define gene

  a section of DNA that codes for a particular sequence of amino acids that code for a particular picture
• Basic ideas of DNA

  genetic material

  a polymer

  • long chained molecule
  • 2 strands
  • 4 bases A-T C-G
• Define genotype

  a combination of alleles that an individual has (e.g. Bb)
• Define phenotype

  resulting characteristics that are expressed (e.g. Brown fur)
• basic ideas of sexual reproduction

  involves the fusion (joining) of male and female gametes

  mixing of genetic information from both parents
• basic ideas of asexual reproduction

  one parent

  does not involve gametes

  no mixing of genetic information

  offspring genetically identical to parent (clones)

  only involves mitosis
• benefits of the human genome

  search for genes linked to a disease

  understand and treat inherited disorders

  trace human migration patterns from the past
• Define alleles

  different versions of genes
• basic ideas of cystic fibrosis

  disorder of cell membranes

  controlled by a single gene

  must have two recessive genes to be a sufferer
• issues of embryo screening

  expensive, money could be spent elsewhere in health service

  unethical, large number of embryos created but only small number implanted. some healthy embryos are destroyed

  unethical, may be able to screen embryos to produce offspring with desirable features