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Transcript
BIOLOGY 177-201B
Mid-Term 2001
Correct answers underlined
1. Nuclear-encoded proteins with no intrinsic amino acid signal sequence will
a) not be fully translated
b) exit the cell via constitutive secretion
c) exit the cell via regulated secretion
d) migrate to perioxomes
e) are translated and remain in the cytoplasm
2. You would expect nuclear-encoded citrate synthase and other enzymes of the
citric acid cycle to have
a) stromal-import sequence
b) stromal-import sequence and thylakoid-targeting sequence
c) intermembrane space-targeting sequence
d) matrix-targeting sequence
e) chaperone-targeting sequence
3. The major function of the signal recognition particle (SRP) is to
a) start translation
b) stop translation
c) start transfer
d) stop transfer
e) open translocon
4. In the Cisternal Maturation (or Cisternal Progression) model of transport
through the Golgi, vesicles bud off
a) medial golgi and travel by retrograde transport to cis golgi
b) medial golgi and travel by retrograde transport to trans golgi
c) cis golgi and travel by anterior transport to medial golgi
d) ER and travel by anterior transport to medial golgi
e) trans golgi and travel by anterior transport to cis golgi
5. A protein inserted into the RER membrane has the following topogenic
features, arranged sequentially from the N terminus to the C terminus:
signal sequence (or signal peptide), stop-transfer sequence, membrane-anchor
sequence (or internal signal-anchor sequence), and stop-transfer sequence, with
various lengths of hydrophilic amino acids in between these sequences.
The protein will have
a) 3 transmembrane segments with both termini in the cytoplasm
b) 3 transmembrane segments with the N-terminus in the cytoplasm and
C-terminus in the ER lumen
c) 3 transmembrane segments with the N-terminus in the lumen of the ER
and
C-terminus in the cytoplasm
d) 4 transmembrane segments with the N-terminus in the cytoplasm and
C-terminus in the ER lumen
e) 4 transmembrane segments with the N-terminus in the lumen of the ER and
C-terminus in the cytoplasm
6. The enzyme protein disulphide isomerase (PDI)
a) contains mannose 6-phosphate
b) contains a KDEL sequence
c) is a digestive enzyme secreted from pancreatic cells
d) functions only at acid pH
e) catalyses hydrolyis of the GTP in SAR-GTP binding proteins
7.Which of the following would NOT cause an increase in the LDL/HDL ratio?
a) malfunctioning clathrin
b) reduced expression of the LDL receptor
c) increased expression of apoprotein A
d) increased expression of apoprotein B
e) decreased production of estrogens
8. The concentration gradients of sodium and glucose across a normal
membrane are the SAME. However, the energy released when each diffuses
across the membrane until there is no net flux is greater for sodium. Why?
a) sodium is smaller
b) sodium has a larger partition coefficient
c) glucose moves across by facilitated diffusion
d) sodium diffuses through channels
e) sodium has a positive charge, glucose is uncharged
9. Life as we know it is dependent on the chemistry of phospholipids because
a) their amphipathic nature allows compartmentalization
b) they capture light energy
c) they lower the Tm of membranes
d) glucose can diffuse through them into cells
e) ions can diffuse through them into cells
10. When the number of fluid lipid rafts in a cell membrane significantly
DECREASES
a) the membrane will more likely be in a disordered liquid phase
b) the amount of cholesterol in the membrane increases
c) number of functional proteins in the membrane will decrease
d) number of omega 3 fatty acids will increase
e) number of long-chain saturated fatty acids will decrease
11. Which of the following statements BELONGS in a reductionist approach to
biology?
a) matter is alive when it contains a vital life force
b) living matter is biochemically extremely diverse
c) the organism is the basic unit of life
d) the organism is the sum of all the activities of individual cells
e) knowledge of all the activities/functions of every cell and system in
an organism will not lead to understanding of the organism as a whole
12. The strongest known oxidant is
a) P 680 + in photosystem 2
b) plastocyanin
c) water
d) oxygen
e) rubisco
13. Which of the following is ACTIVE transport?
a) glucose leaving intestinal epithelial cells
b) glucose leaving liver cells
c) glucose entering liver cells
d) calcium entering cells
e) calcium leaving cells
14. Normal blood glucose concentration is 5 mM.
If a person has inherited a genetic trait such that the uniporter GLUT2 in their
liver cell membranes has a Km of 5 mM, entry of glucose into liver will
a) be saturated at normal blood gluose concentrations
b) be faster at normal blood glucose concentrations than in normal people
c) be proportional to the concentration of blood glucose
d) be slower at normal blood glucose concentrations than in normal people
e) stop
15. Which of the following statements is TRUE about equilibrium
a) Keq > 1
b) Keq < 1
c) reactions proceed until the concentration of reactants and products are 1 mM
d) total energy in reactants equals total energy in products
e) concentration of reactants equals concentration of products
16. The poison arsenate interferes with the net ATP yield in glycolysis because
it substitutes for inorganic phosphate (Pi) in
a) oxidative phosphorylation reactions, such as glycolysis step 6 catalysed
by glyceraldehyde 3-phosphate dehydrogenase,
when glyceraldehyde 3-phosphate becomes 1,3-bisphosphoglycerate
b) in oxidative decarboxylation reactions, such as the step catalysed by the
pyruvate dehydrogenase complex when CO2 is released
c) substrate level phosphorylation reactions, such as the step catalysed by
succinyl CoA synthetase in the citric acid cylcle, when
GDP becomes GTP
d) in phosphoryl shift reactions, such as glycolysis step 8 catalysed by
phosphoglycerate mutase, when 3-phosphoglycerate
becomes 2-phosphoglycerate
e) in phosphoryl transfer reactions, such as glycolysis step 1 when glucose
becomes glucose 6-phosphate
17. The conversion of one mole of glucose to two moles of ethanol in
glycolysis / fermentation is accompanied by a NET gain of
a) three moles of ATP
b) two moles of ATP
c) one mole of ATP
d) one mole of NADH
e) one mole of NAD+
18. In gluconeogenesis, phosphoglycerate kinase catalyses the following
reaction:
3-phosphoglycerate + ATP -------->1,3-bisphosphoglycerate + ADP .
DeltaGo’ (standard conditions) = + 4.5 kcal/mol.
Under what conditions will this reaction be able to occur in liver cells?
a) if [ADP] [1,3-bisphosphoglycerate] / [ATP] [3-phosphoglycerate] = 1
b) if [ADP] [1,3-bisphosphoglycerate] / [ATP] [3-phosphoglycerate] = 10]
c) if [ADP] [1,3-bisphosphoglycerate] / [ATP] [3-phosphoglycerate] = 10,000
d) if [ADP] [1,3-bisphosphoglycerate] / [ATP] [3-phosphoglycerate] = 0.1
e) if [ADP] [1,3-bisphosphoglycerate] / [ATP] [3-phosphoglycerate] =
0.0001
19. During mitochondrial electron transport, ubiquinone (CoQ) carries
electrons from
a) cytochrome b to cytochrome c
b) cytochrome c to the cytochrome oxidase (complex IV)
c) cytochrome oxidase to oxygen
d) complex I and complex II to complex III
e) complex III to complex IV
20. Hibernating bears live off stored fat reserves. During hibernation all of the
following will occur EXCEPT
a) carnitine acyl transferases will be active
b) ketone bodies will be formed in the liver
c) triacylglycerol lipase in adipose tissue will be inhibited
d) thermogenin will uncouple oxidation from phosphorylation in some inner
mitochondrial membranes
e) large amounts of water will be released during catabolism of fat
21. Which one of the following statements about the energetics of glucose
metabolism is NOT true?
a) for each molecule of glucose, the citric acid cycle produces 3 NADH,
1 QH2 (or FADH2), and 1 GTP
b) for each molecule of glucose, glycolysis produces 2 ATP and 2 NADH
c) in E. coli, complete oxidation of one molecule of glucose yields 32 ATP
d) for each molecule of glucose, conversion of pyruvate to acetyl CoA yields
2 NADH
e) less energy is captured from oxidation of glucose carbons in glycolysis than
from the beta oxidation of fatty acid carbons
22. How many c subunits will there be in the F0 ring of the F0F1 ATP synthase
in a species in which 1 NADH entering the electron transport chain in the
mitochondria results in the synthesis of 2.00 ATP?
a) 18
b) 15
c) 12
d) 9
e) 6
23 In photosynthesis, ATP synthesis is driven by
a) proton motive force (pmf) across the inner chloroplast membrane
b) pmf across the thylakoid membrane
c) pH gradient across the thylakoid membrane
d) pH gradient across the inner chloroplast membrane
e) the oxidation of NADPH
Both answers accepted
24. Glucagon stimulates glycogen degradation (to glucose) because of
a) inhibition of protein kinase A
b) inhibition of glycogen phosphorylase
c) activation of glycogen synthase
d) activation of protein phosphatase-1
e) activation of protein kinase A
25. Phosphorylated phosphofructosekinase2/fructose 2,6-bisphosphatase2
a) activates gluconeogenesis because fructose 2,6-bisphosphate levels increase
b) activates gluconeogenesis because fructose 2,6-bisphosphate levels
decrease
c) activates gluconeogenesis because fructose 1,6-bisphosphate levels increase
d) activates glycolysis because fructose 1,6-bisphosphate levels increase
e) activates glycolysis because fructose 2,6-bisphosphate levels increase