Genetics

• The genome is the entire genetic material of an organism.
• DNA is a polymer - it has a double helix structure.
• Each gene codes for a particular sequence of amino acids in order to make a specific protein.
• Genome


  The complete set of DNA found in an organism
• Phenotype


  The visible characteristics of an organism which occur as a result of its genes
• Genotype


  The alleles that an organism has for a particular characteristic, usually written as letters
• Each person has two copies of every gene, called alleles
• A zygote is a fertilised egg cell.
• A zygote has the full number of chromosomes.
• There are four different bases in DNA:

  • thymine, T
  • adenine, A
  • guanine, G
  • cytosine, C
• Mutation


  A change in the DNA base sequence
• Things that increase the risk of mutations

  • Carcinogens (harmful chemicals like in cigarette smoke)
  • Certain types of radiation (like x-rays or gamma rays)
• Gene


  A section of DNA that codes for protein
• Triplet/Codon

  A group of 3 bases that codes for one of the 20 different amino acids
• How DNA works to create proteins

  1. Triplets/codons code for amino acids

  2. Amino acids combine in the correct order to form a protein chain

  3. Protein chain folds to form a protein
• Non-coding DNA


  DNA that isn't part of any gene and doesn't code for protein, but can play a role in gene expression
• Types of mutations

  • Substitutions (one base changed)
  • Insertions (extra base inserted)
  • Deletions (base deleted)
• Nucleotide - made up of one sugar molecule (deoxyribose), one nitrogenous base and one phosphate group
• Coding DNA are regions (genes) in the genome of an organism that store the genetic code for making proteins.
• Variation


  Differences between individuals in a population
• Phenotype


  Observable characteristics of an individual due to the interaction of genes and environment
• Genes

  Code for proteins and the genome, which is all of an individual's genes combined
• Except for identical twins, everyone has a unique genome</b>
• Genes and environment


  Interact to determine most of an individual's characteristics
• Mutation

  A change in the DNA code that may change the protein it codes for
• A gene can be dominant or recessive.