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Cell Physiology and Biology key concepts

6 revision pages for Cell Physiology and Biology, each with the key facts, a memory aid where one helps, and the exam traps.

  1. Competitive reversible inhibition: raised apparent Km, unchanged Vmax

    A competitive reversible inhibitor (it comes off again) competes for the active site, raising the apparent Km (substrate concentration giving half of Vmax, the maximal rate) while Vmax is unchanged.

  2. Gla residues and calcium-dependent anchoring of clotting factors

    Gla residues are glutamate amino acids given an extra carboxyl group (a COOH chemical group); they bind calcium and anchor vitamin K-dependent clotting factors to platelet phospholipid.

  3. How enzymes speed reactions without changing equilibrium

    An enzyme lowers the activation energy (the energy hurdle for a reaction), so equilibrium (the point where forward and reverse reactions balance) is reached sooner but not moved.

  4. Nuclear envelope and nuclear pore complexes

    The nuclear envelope is a double membrane around the nucleus that contains nuclear pore complexes, channels built from many proteins that regulate what enters and exits.

  5. Signal peptide and signal recognition particle: targeting to the rough ER

    The signal recognition particle binds a hydrophobic (water-hating) signal sequence at the start of a new chain and takes the ribosome to the rough endoplasmic reticulum (ER) during translation.

  6. Vitamin C and collagen hydroxylation in scurvy

    Hydroxylation (adding OH groups) of proline and lysine, amino acids in the collagen chain, stabilises the triple helix (a rope-like coil of the collagen chains) and needs vitamin C.

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