9.3.2 The Nucleus (Protein Synthesis)

• Nucleus


  Genetic material (DNA) is located in the nucleus. The nucleus controls the activities of the cell
• Chromosome


  Chromosomes are made of DNA which contains genetic material in the form of genes
• There are 46 chromosomes (23 pairs) in the nucleus of human body cells. This is the DIPLOID number
• There are only 23 chromosomes in the nucleus of sperm and egg cells. This is the HAPLOID number
• 23rd pair of chromosomes


  Determines the biological sex of the organism
• XY chromosomes


  Person will be MALE
• XX chromosomes


  Person will be FEMALE
• Nucleotide


  One nucleotide consists of a base, a sugar and a phosphate
• DNA double helix


  DNA winds up to make a double helix shape
• Base pairing in DNA

  A always pairs with T, C always pairs with G
• Sequence of bases in genes


  Determines the sequence of amino acids used to make a specific protein
• Gene


  A length of DNA that codes for a protein

  
• Proteins in the human body


  • Enzymes (e.g. amylase, lipase, protease)
  • Hormones (e.g. insulin, testosterone, oestrogen)
  • Collagen (found in hair and nails)
  • Haemoglobin (found in red blood cells to transport oxygen)
  • Antibodies (produced by white blood cells during an immune response)
  • Carrier proteins in membranes (help move substances across membranes)
• Protein synthesis


  1. Stage 1 (in the nucleus): Gene on DNA is copied to make mRNA, mRNA leaves the nucleus

  2. Stage 2 (at the ribosome): mRNA passes through ribosome, amino acids are put together in sequence according to the bases on mRNA

  
• The gene coding for the protein remains in the nucleus
• Messenger RNA (mRNA) is a copy of a gene
• mRNA molecules are made in the nucleus and move to the cytoplasm

  
• The specific sequence of amino acids is determined by the sequence of bases in the mRNA