PRACTICE TEST BB

• Which type of b-sheet is most stable?

  Antiparallel
• According to the induced fit model:

  The substrate induces a structural change in the enzyme
• Which bonds are intact in a protein that has been fully denatured by heat?

  Peptide bonds
• In a pi-helix the C=O group of residue 20 is hydrogen bonded to the N-H group of residue:

  - N+5

  - 25
• Which of the following bacterial cell component is a good target for antibacterial agents?

  Cell wall
• How many bacterial cells would there be after 3h, if the doubling time was 0.5h and there were 6 x 10^3 cells to begin with? Remember that Nt = N0 x 2n

  3.8 x 100000
• A bacterium that can grow in the absence of oxygen but optimally grows in the presence of oxygen is:

  Facultative anaerobe
• Fluorescent in-situ hybridisation for bacterial identification is based on:

  Binding of complementary nucleic acid
• The term 'treadmilling' is defined as:

  Process where the individual subunits are added, move through and are removed from a microfilament
• Gram-positive bacteria:

  Have a thick cell wall made from peptidoglycan
• Which of the following structures rapidly conveys the transmission of electrical signals between adjacent cells?

  Gap junctions
• Which structure does NOT belong to the endomembrane system?

  Peroxisome
• Contact dependent signalling where membrane ligands bind to neighbouring cell receptors is known as:

  Juxtacrine
• Which one of the following statements about the fate of Pyruvate is TRUE?

  It can be converted to acetyl CoA
• Which one of the following statement about gluconeogenesis is FALSE?

  It is the reverse of glycolysis
• How many molecules of ATP are hydrolysed if 3 sodium ions are pumped out of a cell and two potassium ions are pumped into a cell?

  1
• What is a signal recognition particle?

  A complex that recognises and targets specific proteins to the endoplasmic reticulum
• Which of the following functions is NOT a role of Rab GTPase?

  Binds to clathrin lattices to remove or 'uncoat' clathrin from vesicles
• The mutation causing sickle cell anaemia is a substitution of a:

  • Polar charged amino acid by a hydrophobic one
  • It involves the substitution of glutamic acid (a polar charged amino acid) with valine (a hydrophobic amino acid) in the haemoglobin protein
• Which of the following statements is FALSE?

  They are heterotrophic, prokaryotic organisms
• Which of the following statements, regarding the enzyme phosphofructokinase (PFK) is TRUE?

  • PFK is activated by an increase in AMP levels
  • PFK is inhibited by high levels of citrate
• In eukaryotic cells, ATP synthesis occurs:

  In both the cytoplasm and the mitoplasm (matrix) of the mitochondria
• An Alpha-helix has the sequence: MECHANISTIC. The CO group of alanine is hydrogen bonded to the NH group of which residue?

  • I
  • n+4