General Terms

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General Terms
2013-08-16 21:33:36

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  1. What is the function of anhydrases?
    They remove water from a substrate.
  2. What is the difference between a synthase and a synthetase?
    Both enzymes catalyze chemical synthesis. Synthetases involve concurrent hydrolysis of a nucleoside triphosphate such as ATP whereas sythases do not.
  3. What is the function of hydrolases?
    They break chemical bonds with the addition of a water molecule.
  4. What is the function of isomerases?
    They rearrange the atoms of a substrate without changing the number or type of atoms within it.
  5. What is the function of endo- and exo- nucleases?
    These enzymes digest DNA or RNA. Endonucleases cut in the middle of an oligonucleotide whereas exonucleases cut from the ends of an oligonucleotide.
  6. What is the function of proteases?
    They digest, or break down, proteins.
  7. What is the function of lyases?
    They break chemical bonds without addition of water or oxygens.
  8. What is the function of cyclases?
    They make a cyclic product from a non-cyclic substrate (i.e. AMP into cAMP). Adenylyl cyclases catalyzes the following reaction: ATP -> 3',5' cyclic AMP + PPi.
  9. What type of enzyme is this (hint: it functions as two enzymes in one)?
    It is both a cyclase (because it makes a cyclic product) and a lyase (because it cleaves its substrate without adding water or oxygen to the product).
  10. What is chemical oxidation?
    Oxidation (catalyzed by oxidases) is the loss of electrons by a molecule or atom. For instance, when Fe+2 is oxidized, it becomes Fe+3.
  11. What is chemical reduction?
    Reduction (catalyzed by reductases) is the gain of electrons by an atom or molecule. It causes a reduction in charge.
  12. What is the function of dehydrogenases?
    They oxidize a substrate by moving a hydride ion from the substrate to an acceptor such as NAD+ or NADP+, forming NADH or NADPH, respectively.
  13. What is the function of oxidoreductase enzymes?
    They transfer an electron from a reductant (electron donor) to an oxidant (electron acceptor).
  14. What is the function of kinases and phosphatases?
    Kinases add a phosphate to a substrate. Phosphatases remove a phosphate (Note that a phosphate is a PO4 group and has a net charge of -3).
  15. What is the function of ligases?
    They covalently bond, or ligate, two molecules (DNA ligase, for instance will 'stitch' two DNA strands to one another).
  16. What is an acyl group?
    It is a R-C=O- group, where R represents a single bonded alkyl group.
  17. What is the function of methylases?
    These enzymes add a methyl group (CH3) to a substrate.
  18. What are anions and cations?
    Anions are negatively charged molecules. Cations are positively charged molecules.
  19. What is a carbonyl group?
  20. It is a C=O group with two substituents on the carbon (in addition to the oxygen).
  21. What is the difference between an amine and an amide?
    An amine is a nitrogen with ammonia-like geometry. An amide is an amine coupled to an acyl group (i.e. in a peptide backbone).
  22. What happens during carboxylation and decarboxylation reactions? Carboxylation: addition of CO2 to a substrate. Decarboxylation: removal of CO2 from a substrate
  23. What is pyrophosphate and what is its formula and net charge? Pyrophosphate (PPi) is an anion composed of two phosphates. It has a formula of P2O7 and a net charge of -4.
  24. What is the function of nucleotide polymerases and what are their substrates?
    They catalyze elongation of RNA and DNA. Their nucleotide substrates are NTP's (for RNA) and dNTP's (for DNA). Note that one PPi is released after each addition step.

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