2.4- PROTEINS

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  • 2.4- PROTEINS
    • THE FOUR LEVELS OF PROTEIN ORGANISATION STRUCTURE
      • Primary
        • The order in which the specific amino acids are combined.
          • The alpha-carbon is bonded to:
            • A hydrogen atom
            • A carboxyl group
            • An amino group
            • A variable group
      • Secondary
        • Refers to the coiling or the folding of a polypeptide chain.
          • The alpha helix structure resembles a coiled spring, and is secured by H-bonding in a peptide chain.
          • The beta helix structure appears to be folded, and is held with H-bonding between peptide units of adjacent chains.
      • Tertiary
        • Refers to the 3D structure of the polypeptide chain.
          • Hydrophobic interactions contribute to the folding and shaping of the protein.
          • Hydrogen bonding helps to stabilise the protein structure
          • Ionic bonding can occur between positive and negative R groups.
          • Disulfide bridges are caused by covalent bonding between R groups of cysteine amino acids
      • Quaternary
        • Refers to the structure of a protein maromolecule formed by interactions between multiple peptide chains.
    • WHAT IS A PROTEOME?
      • The entire complement of proteins that is, or can be, expressed by a cell, tissue or organism.
    • TYPES OF PROTEIN
      • Rubisco
        • The enzyme (ribulose bisphosphate) that catalyses the first reaction of the Calvin Cycle.
      • Insulin
        • A hormone, produced by the pancreas, that causes a decrease in blood sugar levels and an increase of sugar inside the body’s cells.
      • Immunoglobulin
        • Another name for an antibody that recognises antigens, as part of the immune system’s response.
      • Rhodopsin
        • A pigment, found in the retina of the eye, which is particularly useful in conditions of low light.
      • Collagen
        • The main protein component of connective tissue, which is mostly found in skin, tendons and ligaments.
      • Spider silk
        • A fibrous protein spun by spiders, for making webs and drop lines, and building nests
    • FIBROUS AND GLOBULAR PROTEINS
      • Fibrous Proteins
        • Shape: Long and narrow.
        • Role: Structural, for strength and support.
        • Solubility: (Generally) insoluble in water.
        • Sequence: Repetitive amino acid sequence.
        • Stability: Less sensitive to changes in temperature, pH, etc.
        • Examples: Collagen, fibrin, keratin, elastin.
      • Globular Proteins
        • Shape: Spherical.
        • Function: Functional, for transport, catalysing reactions.
        • Solubility: (Generally) soluble in water.
        • Sequence: Irregular amino acid sequence.
        • Stability: More sensitive to changes in temperature, pH, etc.
        • Examples: Catalase, haemoglobin, insulin.
    • POLAR AND NON-POLAR AMINO ACIDS
      • Polar Amino Acids
        • Hydrophilic   R groups.
        • For water-soluble proteins, they are found on the surface.
        • For membrane-bound proteins, they line the interior pores.
      • Non-Polar Amino Acids
        • Hydrophobic R groups.
        • For water-soluble proteins, they are found in the centre.
        • For membrane-bound proteins, they line the interior pores.
    • http://www.ib.bio ninja.com.au/ higher-level/topic-7-nucleic-acids-and/75-proteins.html

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