Inheritance, Variation and Evolution

• a gene is a small section of DNA found on a chromosome
• These genes code for specific sequence of amino acids which form specific proteins
• An allele is a different form of the same gene
• A genome is all the genetic info of an organism
• describe how....can be produced by genetic engineering?

  the gene for ... production is isolated from the human body cells . It's cut out from the genome using restriction enzymes. Use the same restriction enzymes to cut open a plasmid. The plasmid is the vector. The gene for ... is the inserted into the plasmid using the enzyme DNA ligase. This forms a recombinant DNA plasmid which is then inserted into the bacterial cells which will then grow and reproduce. The ... will be extracted and purified.
• a dominant allele is one that is always expressed even if there is only one copy present
• a recessive allele is only expressed if 2 copies of the allele are present. If there is a dominant allele present then the recessive allele will not be expressed
• homozygous is when two copies of the same allele is present
• heterozygous is when 2 different copies of an allele is present
• genotype is the alleles that are present in the genome
• phenotype is the physical characteristics that are expressed by those alleles.
• genetic screening can be done to check if a foetus has an inherited disorder
• cystic fibrosis


  affects the respiratory system

  thick sticky mucus blocks the airways

  reduces the efficiency of gas exchange

  recessive allele
• polydactyl


  extra digits

  dominant allele
• selective breeding is the process by which humans breed animals and plants by specific genetics