DNA and inheritance

• a gene is a section of DNA that codes for a specific characteristic or protein
• alleles - different forms of the same gene
• DNA molecules are in the shape of a double helix
• The edges of the 'ladder' are made of sugar and phosphate - called the backbone
• Adenine (A) always pairs with Thymine (T)
• Cytosine (C) always pairs with Guanine (G)
• triplet codes consist of 3 bases
• 3 bases code for 1 amino acid
• amino acids make proteins
• genetic profiling - analysis of DNA using patterns
• uses of DNA fingerprinting -

  • to determine a child's parentage
  • criminal investigations
  • to determine genetic disorders
• For DNA database -

  • DNA evidence collected from a crime scene can implicate or eliminate a suspect
  • can also help to identify victims
  • has helped solve numerous crimes since the 1980s
  • could help solve an unsolved crime
  • identify paternity or family relationships
  • identify the presence of a genetic disorder
• against DNA database -

  • possibility of DNA being planted at a crime scene
  • cost of maintaining and developing the database are high
  • data might get into the hands of commercial companies
  • it invades our right to privacy
• monohybrid cross - the simplest genetic cross involving one characteristic
• genetic engineering - the deliberate modification (changing) of an organisms genes
• modern uses of genetic modification -

  • manufacturing insulin
  • greater yield in crops
  • crops resistant to disease
  • discovering where genes are expressed in the body
• advantages of genetic modification in crops -

  • pest, herbicide or disease resistant crops
  • crops that withstand frost
  • crops that produce increased yield
  • improving health
• genetic modification can offer potential treatment of genetic disorders in future - could lead to better quality of life and longer life expectancy
• disadvantages of genetic modification in crops -

  • cross pollination with weeds may lead to pest and herbicide resistant weeds
  • GM crops can be made not to reproduce - leads to growers buying seeds annually
  • reduction in biodiversity
  • some people believe there could be currently unknown health risks
  • research is carried out on animals
• genetic modification can be a risk to human life
• genetic modification may lead to designer babies in the future - allowing parents to choose genetic make-up of child
• gene - a length of DNA that codes for one protein
• chromosome - a length of DNA that contains many, found in the nucleus and visible during cell division
• genotype - the genetic make-up of an individual
• phenotype - the description of the way the genotype 'shows itself'
• selfing - a technique by which pollen from a plant is used to fertilise ovules in flowers of the same plant