BIOL3030 Which of the following does not have a membrane

13 Jun BIOL3030 Which of the following does not have a membrane

Choose one best answer to each question.
1. Which of the following does not have a membrane?
A. nucleus
B. ribosome
C. mitochondria
D. lysosome
E. all of the above have a membrane
2. Which does NOT belong to the three principal forms of protein secondary structures?
A. ? helix
B. ? turn
C. zinc finger
D. ? sheet

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3. Prokaryotes are unicellular whereas Eukaryotes are multicellular.
A. true
B. false
4. To express the information coded in DNA into proteins, we need
A. Transcription
B. Replication
C. Translation
D. Both a and c
E. Both a and b
5. Which of the following are found in prokaryotes?
A. mitochondria
B. nucleus
C. ribosome
D. plasma membrane
E. b and c

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6. Which of the following requires the most energy to break?
A. Peptide bond
B. Hydrogen bond
C. Hydrophobic interaction
D. Ionic bond
7. The chemical reaction :

What would happen if you add more X?
A.
B.
C.
D.

Nothing, the reaction will stay at equilibrium
The rate of the reverse reaction will increase
Keq will increase
The rate of the forward reaction will increase

can be represented by the following equation:

8. The exoplasmic leaflet of the endoplasmic reticulum membrane faces:
A. The cytoplasm
B. The lumen
C. The extracellular space
9. The ABC family of transporters transports small molecules down their gradient (from high to low
concentration).
A. True
B. False

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10. The organelle that contains hydrolytic enzymes to degrade macromolecules is the:
A. peroxisome
B. mitochondria
C. nucleosome
D. lysosome
E. chloroplast
11. Eukaryotic cells differ from prokaryotic cells by having which of the following:
A. Membrane-bound nucleus
B. mitochondria
C. plasma membrane
D. a and c
E. a and b

12. A transporter protein displays much higher affinity towards glucose than galactose. We should expect that
A. Its Km for glucose should be much smaller than for galactose
B. Its Km for glucose should be much higher than for galactose
13. The active site of an enzyme
A. is usually only a small part of the protein
B. comprises substrate binding and catalytic sites
C. is found on the surface of a protein
D. all of the above

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14. The smooth endoplasmic reticulum is associated with ribosomes.
A. True
B. False

15. Which statement concerning proteins is FALSE?
A. Ubiquitin is covalently linked to proteins
B. Allosteric effects on a protein can positively or negatively affect its functions.
C. Protein phosphorylation is a type of reversible covalent modification.
D. Proteolytic cleavage is the same as protein degradation.
16. In normally functioning mitochondria, the H+ concentration is
A. higher in the matrix than in the intermembrane space
B. higher in the intermembrane space than in the matrix

17. Which of the following statement is TRUE for lipid components in the biomembranes?
A. The lipid composition on different membranes and different leaflets is different.
B. Phosphoglycerides, plasmalogens and sterols are the major lipid molecules in membranes.
C. A phospholipid molecule usually spans the entire membrane thickness.

18. V-class and F- class H+ pumps are structurally similar but perform different functions. The difference in the
function of these pumps is:
A. the F-class pumps H+ consumes ATP while the V-class makes ATP (ie phosphorylates ADP)
B. the F-class pumps H+ makes ATP while the V-class pumps consume ATP
C. F-class pumps are found only in bacteria whereas V-class pumps are found in all organisms
19. Integral membrane proteins generally:
A. are bound to the membrane indirectly through interactions with other membrane proteins
B. are anchored in the membrane by covalent binding to lipid molecules in the membrane
C. do not enter the phospholipid bilayer
D. have one or more transmembrane domains that interacts with the hydrocarbon core of the phospholipid
bilayer.

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20. Which of the following statement is WRONG for lipid components in the biomembranes?
A. Polar head groups face hydrophilic space.
B. The fluidity of phospholipids on the membranes is affected by temperature.
C. The thickness of the membrane is affected by the lipid composition.
D. Phospholipids frequently flip from one leaflet to another.

21. In a globular protein found in the cytosol, one would expect to find alanine, a hydrophobic amino acid:
A. On the surface of the protein
B. Near the N-terminus of the protein
C. At the C-terminus of the protein
D. In the inner core of the protein
22. Co-transport uses ___________ proteins that couple movement of one ion or molecule against its
concentration gradient with movement of another molecule or ion down its concentration gradient.
A. channel proteins
B. uniporters
C. antiporters or symporters
D. ATP powered pumps

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23. Frog eggs in the pond do not burst because
A. There is no net osmotic pressure across their plasma membrane.
B. The ion concentrations inside the eggs are roughly the same as the pond water.
C. There is no aquaporin on the plasma membrane of eggs.
D. There is higher glucose concentration inside eggs.

24. Specific antigen-antibody interaction is a best example of
A. molecular complementarity
B. macromolecules in the biosystems are built from smaller component molecules.
C. requirement of high-energy chemical bonds

25. The low pH in the lumen of animal lysosomes is a result of the pumping of protons by active transport and
the facilitated diffusion of Cl- ions.
A. True
B. False
26. Maintaining the resting membrane potential in animal cells require both functional Na+/K+ ATPase and K+
channels.
A. True
B. False

27. About the selectivity of K+ channels, which statement is WRONG?
A. The protein segments constituting the selectivity filters are homologous in all K+ channels.
B. K+ passes through the channel as a hydrated ion.
C. Na+ cannot pass through K+ channel because it could not interact efficiently with the interior selective
groups lining the channel.
D. K+ moves down its concentration gradient.
28. The Na+/Glucose transporter is a:
A. uniporter
B. symporter
C. channel protein
D. none of the above

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29. Which is NOT a mechanism to make lipid anchored membrane proteins?
A. C-terminal Prenylation
B. N-terminal Acylation
C. Covalently linking to glycosylphosphatidylinositol (GPI)
D. Protein phosphorylation
30. The increased resolution possible with electron microscopy is due to
A. The use of magnets to focus the electron beam
B. The scattering of electrons by large atomic nuclei
C. The short wavelength of the electron beam
D. The use of specific stains with ultrathin specimens

31. Protein domains are:
A. composed of multiple interacting polypeptides
B. a region within a polypeptide that has a specific structure and/or function
C. a type of secondary structure
D. normally hydrophobic

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32. Which of the following is FALSE about the nucleus?
A. the outer lipid bilayer of the nucleus is contiguous with the endoplasmic reticulum
B. has nuclear pores that allow materials to move between the nucleus and the cytosol
C. has a double membrane
D. contains a subcompartment called the nucleolus
E. is the major site to synthesize ATP

33. Metabolism of one glucose molecule in human cells normally generates _______ molecules of ATP under
aerobic conditions (ie with oxygen).
A. 2
B. 4
C. 16
D. 30
34. About glycolysis, which statement is FALSE?
A. It happens in the cytosol
B. It generates two pyruvate molecules
C. No net ATP are generated after glycolysis
D. It does not require oxygen

35. Amphipathic lipids spontaneously arrange themselves in order to maximize hydrophobic and hydrophilic
interactions. Which of the following structures are created by this process.
A. Micelles
B. Microsomes
C. Bilayers
D. All of the above

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Questions 36 and 37. In the experiment shown, a tissue homogenate has been subjected to two rounds of
centrifugation to produce the pellets and supernatants indicated.

36. Where would you expect to find nuclei?
A. I and IV
B. II and IV
C. IV, and V
D. I and III

37. Where would you expect to find ribosomes?
A. II
B. IV and III
C. IV
D. I, II and V

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38. About protein folding, which statement is FALSE?
A. The three dimensional structure of a protein is determined by its primary amino acid sequence.
B. Molecular chaperones facilitate protein folding by preventing the formation of aggregates between
newly synthesized proteins.
C. Most proteins in the cytosol expose hydrophopic sidechains at the surface of the molecules.
D. Protein folding involves establishing interactions between sidechains of residues along the polypeptide.
39. Every protein has a quaternary structure.
A. True
B. False

40. A protein family is a group of proteins that show structural similarity and perform similar functions.
A. True
B. False
41. Which of the following is NOT considered as a MOTIF?
A. coiled coil
B. ?-sheet
C. helix-loop-helix
D. zinc finger

42. About ATP synthase, which is FALSE?
A. ATP synthase is localized at the inner membrane of mitochondria.
B. ATP synthase makes ATP from ADP and Pi.
C. ATP synthase is composed of F0 and F1 parts.
D. ATP synthesis happens in the absence of O2.
43. Proteasomes are macromolecular machines involved in
A. protein synthesis
B. protein degradation
C. protein folding
D. protein transport

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44. Proteins that are recognized by the proteasome must first be marked by:
A. Phosphorylation
B. Attachment of fatty acyl group
C. Covalent linkage to the protein ubiquitin
D. Association with the chaperone HSP70
E. Methylation

45. Asymmetrical distribution of lipids in the cytoplasmic versus exoplasmic face of the plasma membrane may
be a consequence of where these lipids are synthesized.
A. True
B. False
46. Enzymes can accelerate a chemical reaction because they:
A. alter the Keq of the reaction
B. alter the Km of the reaction
C. alter the activation energy
D. alter the delta G of the reaction

47. Subcellular organelles can be isolated and partially purified using
A. differential centrifugation
B. light microscopy
C. fluorescence recovery after photobleaching
D. electron microscopy

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48. Cholesterol mixes with phospholipids in a biomembrane because cholesterol molecules are
A. glycoslyated.
B. hydrophobic.
C. hydrophilic.
D. phospholipid derivatives.
49. About electron transport in the mitochondria, which statement is FALSE?
A. NADH is oxidized to NAD+ H+
B. FAD is oxidized to FADH2.
50. About citric acid cycle, which statement is WRONG?
A. The enzymes involved are localized in the mitochondrial matrix.
B. Acetyl CoA donates 2 carbons to get the cycle started.
C. At the end of the cycle 2 pyruvate molecules are formed.
D. No O2 are required for the citric acid cycle

Bonus questions (ie exam is graded out of 50)

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51-53. Refer to the following figure and correlate the name of organelles with structures indicated by numbers.

51. Mitochondria
a. 1
b. 2
c. 3
d. 4

52. Golgi complex
a. 7
b. 8
c. 9
d. 10

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53. Smooth endoplasmic reticulum
a. 7
b. 8
c. 9
d. 10