genetics

• Sexual reproduction

  • fusing of gametes
  • egg / sperm cell
  • genetically different offspring
  • positive - genetic variation so can adapt
  • negative - requires a lot of time and energy
  • have to have 2 parents
• Asexual reproduction

  • one parent
  • genetically identical offspring
  • positive - faster than sexual reproduction
  • negative - no genetic variation so less likely to survive environmental change
• DNA structure

  • double helix
  • sugar phosphate backbone
  • complimentary base pairs
  • a + t / c + g
  • weak hydrogen bonds
• gene - small section of DNA
• genome - all of an organisms genetic material
• allele - different versions of a gene
• homozygous - 2 of the same alleles
• hetrozygous - 2 different alleles
• dominant allele - only needs one copy to be expressed
• recessive allele - needs two copies to be expressed
• genotype - alleles someone has
• phenotype - physical characteristic from that genotype
• DNA - polymer

  • nucleotides (monomers) join to form a strand
• Protein synthesis - transcription

  • in nucleus
  • DNA unravels
  • RNA polymerase joins in the non coding region
  • moves along DNA
  • adds complimentary rna nucleotides
  • forms mRNA
  • leaves nucleus through nuclear pores and move into the cytoplasm
• Protein synthesis - translation

  • mRNA strand joins to a ribosome
  • it moves along the strand
  • adds complimentary tRNA base pairs
  • 3 base pairs (codon) codes for 1 amino acid
  • many amino acids join together to form a polypeptide chain
  • folds to form a protein
• variation - a difference in the characteristics of individuals
• variation types

  • inherited
  • environmental
• Natural selection

  • survival of the fittest
  • when environmental conditions change animals must adapt to survive
  • those who don't adapt will die
• evolution - change of characteristics over time
• mutation - change in base sequence of DNA

  • carcinogens / chemicals that cause cancer
  • x-rays / gamma rays
• gene has a mutation - folds into a different protein so it can no longer carry out it's function
• human genome project

  • map out the complete human genetic code
  • sequence all 3 billion DNA base pairs in the human genome
• Benifits of HGP

  • understand genetic diseases
  • early detection / treatment
  • develop personalised medicines
• Antibiotic resistance

  • bacteria infects someone
  • some bacteria have a mutation so are less suseptable to antibiotics
  • antibiotics kill the non resistant bacteria
  • other bacteria reproduce passing on the mutation
  • continues through generations
  • become resistant
• culturing bacteria - grow bacteria in a controlled laboratory environment
• agar - jelly like substance used as solid medium to culture bacteria
• bacterial colony - visible cluster of bacteria grown from a single bacterium
• aseptic technique - procedure to prevent cross contamination
• incubator set to max of 250C - prevent harmful pathogens growing