BIOCHEM Midterm Two - Part I

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BIOCHEM Midterm Two - Part I
2013-11-07 22:09:56
Biochem Midterm Two

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  1. Why are Enzyme Kinetics Important in Biochemistry?
    • Catalytic Rate & Binding Efficiency
    • Determination of Catalytic Mechanism
    • Metabolism (Role in Pathway)
    • Assays
  2. Reaction Mechanism
    Description of all Elementary Steps in a chemical Reaction
  3. What are the the units of k for,
    A First order reaction?
    A second order reaction?
    • First Order - s-1
    • Second Order - M-1s-1
  4. What is the effect of a Catalyst on the reverse reaction?
    It is also catalysed
  5. E+S -> ES -> E+P
    Where is the rate determining step?
    ES -> E+P
  6. What are the two Assumptions for rewriting the reaction equation?
    • Steady State Assumption - ES is constant during measturement.
    • Equillibrium Assumption - Bind/Release is fast compared to catalysis
  7. What are the roles of Nucleotides in living things?
    • Monomers of Nucleic Acids
    • Energy Supply (ATP)
    • Enzyme Cofactors
    • Catalysis (rRNA)
  8. Are Nucleotide Bases Aromatic?
  9. What isomer of Ribose is used in Ribonucleic acids?
    • Beta-D-Stereoisomer
    • (Beta is the orientation of OH on the ribose(No Base) with respect to the O "bridge".
  10. What does dA, dT, dC and dG mean? Why is there no dU?
    The d stands for deoxy. There is no dU because U is only found in RNA
  11. What is a common modification to bases?
  12.                 DNA absorbs higher energy UV light
  13. What does C2' Endo mean?
    The 2' carbon (in the pentose) is in the same direction of the 5' carbon (usually up).
  14. What is the true structure of the ribose (cyclic part)?
    • Three of the five atoms are in the plane of the ring.
    • The 2' and 3' opposite to eachother both above and below the ring (and vice-versa)
  15. In what two ways can multiple gene products arise from different combinations of exons?
    • Alternative Splicing
    • Exon Shuffling
  16. That are the sizes (in S) of the large and small subunits in,
    • Bacteria - 30S + 50S
    • Eukaryotes - 40S + 60S
  17. During elongation, how is equillibria kept towards the formation of an mRNA polymer?
    • The released diphosphate from the addition of a nucleotide is further cleaved by another enzyme.
    • Taking advanage of le chatelier
  18. What subunits make up the RNAP apoenzyme enzyme? What is the role of σ70?
    • RNAP Apoenzyme - αββ'ω
    • σ70 is a cofactor and therefore is a part of the Holoenzyme
  19. What are the three post transcriptional modifications to mRNA?
    • Pseudo U
    • 2'-O-Methylation
    • Base modification