2.3 - DNA and inheritance

• DNA has a double helix structure
• DNA is made up of 2 sugar phosphate backbones with 4 different nitrogenous bases
• the sugar phosphate backbones are bonded by covalent bonds
• the 4 different nitrogenous bases are:

  • Adenine
  • Thymine
  • Cytosine
  • Guanine
• adenine, thymine and guanine, cytosine are complementary pairs (always pairs)
• the nitrogenous bases are held together by hydrogen bonds
• a long molecule of DNA is a chromosome
• a section of DNA is a gene
• the sugar phosphate backbone of DNA is antiparallel
• a monomer - is a molecule that can be bonded to other identical molecules to form a polymer
• nucleotide is made up of 3 separate parts:

  • nitrogenous base
  • sugar
  • phosphate
• a mutation is a genetic mistake
• 3 bases codes for 1 amino acid (triplet code)
• amino acids are bonded together to form proteins
• the sequence of amino acids determine the shape of the protein
• the nucleus contains chromosomes
• 3 nitrogenous bases codes for 1 amino acid which bonded tog will form proteins. some proteins are enzymes and they affect the functioning of the cell and the inherited characteristics
• genetic profiling is the analysis of an organisms DNA
• DNA profiling is used in criminal cases, paternity cases and classification between species
• DNA carries the genetic code that determines the characteristics of a living thing
• an allele is a different version of the same gene
• heterozygous is when the alleles of a particular gene are different
• homozygous is when the alleles of a particular gene is the same
• recessive is the less dominant allele and is only expressed when when inherited from both parents
• phenotype is the characteristic that is shown
• genotype is the pair of letters
• we have 2 genes for every characteristic