Cell Biology Revision Questions for Chapter 3:
Part-1: ENZYMES ANS CELL SIGNALLING
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This Revision Questions will be available on this site till Tuesday the 10th of December 2013 (NB: Due to the Mathematics Visiting Lecturer these revision questions will remain til another week on this site
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Instructions: Answer all the 10 questions by selecting the single letter that best answers the question. Select:
A: If all the answers are correct
B: if none of the answers is correct
C: if 1, 2, & 3, are correct
D: If 1, & 3 are correct
E: If 2, & 4, are correct
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(1) Enzymes are
(1) Biological catalysts
(2) More than 40 000 different types in the human cell
(3) Were first discovered by Buchner in 1900
(4) Are unnatural proteins
(2) Metabolism involves
(1) Anabolism
(2) Endagonism
(3) Catabolism
(4) Exogonism
(3) Enzymes inhibition can be
(1) Inhibitive
(2) Competitive
(3) Non inhibitive
(4) Non-competitive
(4) The following factors affect the activities of enzymes
(1) Temperature
(2) pH
(3) Both enzyme and substrate concentrations
(4) Covalent medications
(5) Michealis-Menten Constant is
(1) Inversely proportional to Vmax
(2) Measured using the substrate concentration
(3) Determined using the rate of reaction
(4) Measured using pH
(6) Lineweaver-Burk curve determines the effect of
(1) Competitive inhibitors
(2) Allosteric inhibition
(3) Non-competitive inhibition
(4) Non-allosteric inhition
(7) Cell signaling can use
(1) Endocrine
(2) Paracrine
(3) Autocrine
(4) Enzycrine
(8) Steroid hormone receptors are
(1) Found within the nucleus
(2) Dimers of zinc-finger proteins
(3) Are affecting the DNA functioning
(4) Are transmembrane proteins.
(9) G-protein coupled receptors are
(1) Transmembrane proteins
(2) Cytosolic
(3) Wind 7 times back and forth
(4) Nuclear
(10) G-protein coupled receptors have the following second messengers
(1) cATP
(2) cAMP
(3) IPII
(4) IPII
From Number 11 to 16: Select the best answer
(11) Which of the following statements is false about enzyme kinetics (a) An increase in the substrate concentration (at constant enzyme concentration) leads to proportional increases in the rate of the reaction (b) Most enzymes operating in the human body work best at a temperature of 37oC (c) An enzyme-substrate complex can either form a product or dissociate back into the enzyme and substrate (d) Maximal activity of human enzymes occurs around pH 7.2.
(12) At which pH would pancreatic enzymes work at maximum activity? (a) 5.3 (b) 6.7 (c) 7.2 (d) 8.5
(13) Some enzymes require the presence of non –protein molecule to behave catalytically. An enzyme devoid of this molecule is can a(n) (a) holoenzyme (b) apoenzyme (c) coenzyme (d) zymoenzyme
(14) Which of the following factors determine an enzyme specificity? (a) the three-dimentional shape of the active site (b) The Michaelis constant (c) The type of co-factor required for the enzyme to be active. (d) the prosthetic group on the enzyme.
(15) Enzymes increase the rate of the reaction by (a) decreasing the activation energy (b) decreasing the overall free energy of the reaction (c) both a and b (d) none of the above.
(16) Bonding between atoms within an enzyme such as trypsin is best describe as (a) glycosidic (b) saccaride (c) ionic (d) van der Waals.