Situational tasks
1
A cat named Lucullus is so spoiled that he will eat nothing but freshly opened canned tuna. Another cat,
Griselda, is given only dry cat food by her far less indulgent owner. Canned tuna is essentially all protein,
whereas dry cat food can be considered 70% carbohydrate and 30% protein. Assuming that these animals have
no other sources of food, what can you say about the differences and similarities in their catabolic activities?
2
The average male with a computer hooked up to the Internet receives thousands of spam e-mails for all kinds
of things, such as Viagra, weight-loss pills, and others not fit to print. Among the spam, one can find offers for
human growth hormone pills guaranteed to make one young again. Why is this unlikely?
3
An athletic friend is preparing to run a marathon and intends to load glycogen before the race. Someone told
your friend that the way to load more glycogen is by exercising exces?sively for two days to deplete the
glycogen stores completely, and that is what your friend intends to do. What do you say about this regimen?
4
The functioning of a particular pathway often depends not only on control enzymes in that pathway but also
on control enzymes of other pathways. What happens in the following pathways under the indicated
conditions? Suggest what other path?way or pathways might be influenced. (a) High ATP or NADH
concentration and the citric acid cycle. (b) High ATP concentration and glycolysis. (c) High NADPH
concentration and the pentose phosphate pathway. (d) High fructose-2,6-bisphosphate concentration and
gluconeo?genesis.
5
People on high-fiber diets often have less can?cer (especially of the colon) and lower blood-cholesterol levels
than people on high-fiber diets often have less can?cer (especially of the colon) and lower blood-cholesterol
levels than people on low-fiber diets, even though fiber is not digestible. Suggest reasons for the benefits of
fiber.
6
Most calcium supplements have calcium carbon?ate as the main ingredient. Other supplements that have
calcium citrate as the main ingredient are advertised as being more easily absorbed. Do you consider this a
valid claim? Why?
7
How does glucagon affect the following enzymes: (a) Glycogen phosphorylase (b) Glycogen synthase (c)
Phosphofructokinase I
8
The epinephrine-mediated “amplification cascade” of Figure 24.14 has six steps, all of which are catalytic
with one exception. This cascade leads to the activation of glycogen phosphorylase. This enzyme acts in turn
9
on glycogen to yield glu?cose-1-phosphate (G-1-P). (a) Which step is not catalytic? (b) If each catalytic step
10
had a turnover (molecules of substrate acted on per molecule of enzyme) of 10, how many molecules of G-1-P
would result from one molecule of epinephrine? (c) What is the biochemical advantage of such a cascade?
1 Аридижи Халиме Хюснийе
2 Бейсембаева Дәриға Рыйқызы
3 Бюйюкдаг Озгюн Бирсу
4 Дуйсенов Тимур Алимович
5 Явуз Дилара
6 Селам Эсра
7 Омар Махер Хасан Альтури
8 Марангоз Юнусемре
дарига
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Describe recurring motifs in metabolic regulation.
Describe major metabolic pathways and control sites.
тимур
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3-й
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5-й
Describe recurring motifs in metabolic regulation.
Describe major metabolic pathways and control sites.
эсра
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Describe key junctions: glucose 6-phosphate, pyruvate, and acetyl CoA.
Explain unique metabolic profile of each organ.