Chpt 2

• protists = large groups of mostly single-celled organisms that cannot be classified as a plant, animal or fungus that have similar characteristics
• organic molecules are complex that are derived from or produced by living organisms and have carbon-hydrogen bonds
• inorganic molecules are simple and are derived from non-living components and have no carbon-hydrogen bonds
• carbohydrates role:

  • important source of chemical energy
  • energy reserves in plants and animals
  • form structural components
  • form part of RNA and DNA
• three main groups of carbohydrates - monosaccharides, disaccharides, polysaccharides
• lipids role:

  • main component of the plasma and organelle membrane
  • storing energy
  • hormones
• lipids are insoluble to water
• two general forms of lipids - simple and compound
• protein functions:

  • catalyse cellular reactions
  • hormones
  • act as carrier molecules
  • form structural components in organisms (collagen)
• a protein is formed by one or more polypeptide chains in a biologically functioning way
• protein = fully functioning molecule
• polypeptide = non-functioning
• nucleus = double membrane, contains genetic information, directs cell activity
• mitochondrion = double membrane, release energy from organic compounds (cellular respiration)
• rough endoplasmic reticulum = membrane bound, synthesises and processes proteins
• ribosome = non-membrane bound, composed of proteins and ribosomal RNA, synthesises proteins
• Golgi apparatus = membrane bound, further processes and packages proteins into vesicles for export from the cell
• chloroplast = double membrane, photosynthesis
• proteome = all the proteins present in a cell or organism
• the structure of proteins - atomic level - proteins are made up of carbon, hydrogen, oxygen, nitrogen and sometimes sulphur
• proteins are made of smaller amino acids, when they joined together they lose a water molecule in a reaction called condensation reaction
• examples of proteins:

  • keratin is a structural protein -> hair, nails, skin
  • haemoglobin is a transport protein that carries oxygen from lungs to the rest of the body
  • lactase -> enzyme that breaks down lactose
• all amino acids have:

  • an amine group (NH2)
  • carboxyl group (COOH)
  • variable R group (or side chain)
• 2 of the 20 different amino acids contain sulfur
• the R group gives the amino acid a name
• amino acids have different properties, basic, polar, non-polar, acidic
• proteomics = large scale study of the structure, function, and interactions of proteins
• enzymes act as a biological catalyst in metabolic reactions
• anabolic reactions = reactions that make larger molecules
• catabolic reactions = reactions that break down larger molecules into smaller molecules
• polypeptide chain = chain of amino acids joined by peptide bonds
• during condensation, monomers (amino acids) are linked via strong covalent bonds and a water molecule is released
• covalent bond can be broken by a hydrolosis reaction
• hydrolosis reaction = addition of a water molecule
• Primary structure of a protein

  • sequence of amino acids that make 2D polypeptide chain
  • genes determine order and number of amino acids
  • linear sequences shorter than 50 amino acids are peptides
  • the linear sequence provides information on how proteins will fold
• secondary structure of a protein

  • predictable repeating pattern of alpha helices and beta pleated sheets due to hydrogen bonding between peptide bonds
  • random coiling is another secondary structure
• tertiary structure of a protein

  • 3D structure where the polypeptide chain folds in due to the various chemical reactions between R groups
  • different areas are affected by the R groups
  • folding process occurs spontaneously in some smaller polypeptides
  • larger proteins need specialised proteins to fold correctly
• quaternary structure of a protein

  • level of structure in which two or more polypeptide chains or prosthetic groups bond together to form a 3D structure
  • only some proteins have a quaternary structure (haemoglobin)
  • chaperonins help with folding
• prosthetic groups = an inorganic compound that is involved in protein structure or function
• conjugated protein = a protein with a prosthetic group eg haemoglobin