Download BIOB111 - Tutorial activity for Session 21

BIOB111 - Tutorial activity for Session 21
General topics for the Week 12 Session 21


Carbohydrate metabolism
Students discuss the processes in groups and answer the questions chosen from the
textbook.
Instructions:
1.
View these animations on the citric acid cycle and gluconeogenesis:
http://higheredbcs.wiley.com/legacy/college/boyer/0471661791/animations/gluconeogenes
is/gluconeogenesis.htm (Link verified 8 October 2015)
2. Which of the following is a reactant in the first step of gluconeogenesis?
a. carbon dioxide
b. GTP
c. glucose
d. phosphoenolpyruvate
3. Which of the following substances are participants in the reactions encompassed by the Cori
cycle?
a. pyruvate and acetyl CoA
b. pyruvate and lactate
c. lactate and acetyl CoA
d. pyruvate, lactate and acetyl CoA
4. Assign each of the reaction characterizations to one of the metabolic pathways listed in the
responses. Responses may be used more than once or need not be used at all.
a) gluconeogenesis
b) glycogenesis
c) glycogenolysis
d) glycolysis
4a
Fructose 6-phosphate is the product formed in the second step of this process.
ANS:
4b.
Formation of UDP-glucose is part of this process.
ANS:
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4c.
Oxaloacetate is the product formed in the first step of this process.
ANS:
4d.
Two trioses combine to form fructose 1,6-bisphosphate as part of this process.
ANS:
4e.
Glucose 6-phosphate is converted to glucose 1-phosphate as part of this process.
ANS:
5. a)
b)
Explain how gluconeogenesis is different from glycolysis.
Identify the irreversible steps in glycolysis and explain how they are different in
gluconeogenesis.
c) How is glucagon involved
6
Learn the citric acid cycle from the text book and the power point slides.
a)
Practice writing an overview of the cycle with the names of the reactants, products
and the enzymes and coenzymes involved.
b)
Then discuss the importance of reduced coenzymes (NADH and FADH2) that are
formed in certain steps - and how they are used to produce energy in the form of
ATP.
7
Answer these questions
a.
Where in the cell does the citric acid cycle (Krebs cycle) occur
b.
Name three other substrates that we can catabolize to produce acetyl CoA?
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STUDENTS TO NOTE
NADH from glycolysis cannot get easily through into the mitochondria and needs to use a
shuttle system, losing some energy in the process. However there are 2 different shuttle
systems, glycerol phosphate shuttle (1.5 ATP) and malate-aspartate shuttle (2.5 ATP)
Pyruvate oxidation occurs in the inner membrane of mitochondrion, so 2.5 is used as the
multiplier
Total ATP from Glucose
Substrate level phosphorylation
ATP
Glycolysis
Citric Acid Cycle (2x1)
2
2
Oxidative Phosphorylation
Glycolysis 2 NADH x 1.5 (2.5)**
Pyruvate (2x1) 2 NADH x 2.5
CAC (2x3) 6 NADH x 2.5
CAC (2x1) 2 FADH2 x 1.5
3 (5)
5
15
3
TOTAL ATP per mole of Glucose:
30/32
** depends on shuttle compound)
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Last Updated on 6-Feb-14
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