BIOC 385 Exam 2 Homework
Questions & answers rated A+
What two reasons best explain why fats are the primary energy storage molecule compared to
carbohydrates?
Carbohydrates have a higher oxidized state than fats, so the energy yield is lower per gram of
material.
Carbohydrates contain too many glycosidic bonds that can only be hydrolyzed by probiotic
bacteria, fats do not.
Fats are easier to eat because they are tasty, carbs are bland and tasteless so evolution favored
fats over carbs.
There are not two correct answers.
Carbohydrates are hydrated, which adds more wet weight so would be a burden to carry around
carbs.
,Fats have a carboxyl group that helps them to form micelles in the digestive track, whereas
carbs are solid - correct answer ✔✔Carbohydrates have a higher oxidized state than fats, so the
energy yield is lower per gram of material.
Carbohydrates are hydrated, which adds more wet weight so would be a burden to carry around
carbs.
What would be the cost in ATP per glucose residue if glycogen phosphorylase and glycogen
synthase removed and added glucose, respectively, to the ends of glycogen at the same time?
Assume that the glucose used in these reactions comes from glucose-6P. Choose the ONE best
answer - correct answer ✔✔1ATP/glucose residue
The role of glycogenin is to - correct answer ✔✔serve as the origin of the glycogen polymer.
Muscle glycogen phosphorylase is regulated by both allosteric effectors, such as AMP and ATP,
and by hormonal signaling. Allosteric effectors bind to the phosphorylated and
unphosphorylated forms of the enzyme and shift the equilibrium between the inactive T
conformation and the active R conformation. In contrast, hormonal regulation involves
activation of kinase and phosphatase enzymes, which modulate the phosphorylation status of
glycogen phosphorylase.
Which TWO statement(s) below best explain the metabolic logic of this dual regulatory
mechanism? - correct answer ✔✔Allosteric regulation by AMP and ATP provides a way to
quickly shift the activity of muscle glycogen phosphorylase between the active and inactive
states before hormonal signaling is fully stimulated
Both forms of control are important because they work together to ensure maximum
interconversion of glucose and glycogen so that liver cells can maintain safe blood glucose levels
at all times
Put the correct steps required for absorption of dietary fats into order.
,-Entry into the circulatory system
-Emulsification of fats
-Chylomicron assembly
-Export of lipoprotein particle
-Intracellular synthesis of triacylglycerols
-Lipase cleavage - correct answer ✔✔1. Emulsification of fats
2. Lipase cleavage
3. Intracellular synthesis of triacylglycerols
4. Chylomicron assembly
5. Export of lipoprotein particle
6. Entry into the circulatory system
Individuals with McArdle's disease has defects in muscle glycogen phosphorylase. As a result,
individuals with McArdle's disease have an exercise intolerance with fatigue and cramps,
however, after a period of exercise they experience a "second wind" of energy. The second wind
results from cardiovascular adjustments that allow glucose to be mobilized from liver glycogen
to fuel muscle contraction, though this is less efficient.
Choose the ONE best answer below that explains why the amount of ATP derived in the muscle
from circulating glucose is less than the amount of ATP that would be obtained by mobilizing
the same amount of glucose from muscle glycogen.
The production of glucose 6-phosphate from glycogen via the enzyme phosphoglucomutase is
coupled to the formation of ATP. Therefore mobilizing glucose from glycogen results in one
more net ATP made than in the conversion of glucose to lactate via glycolysis. - correct answer
✔✔The conversion of glucose to lactate in muscle generates 2 ATP. If muscle glycogen could be
mobilized, the energy yield would be 3 ATP, since phosphorolysis of glycogen bypasses the
hexokinase-catalyzed step of glycolysis that consumes ATP.
, Starting from a molecule of glucose imported from the blood, what is the energy cost for adding
that molecule of glucose to a growing glycogen chain? - correct answer ✔✔2ATP
Glycogen phosphorylase catalyzes the removal of glucose from glycogen. The ΔGo' for this
reaction is 3.1 kJ/mol.
a) Calculate the ratio of [Pi] to [glucose 1-phosphate] when the reaction is at equilibrium at
298K. (Hint: the removal of glucose units from glycogen does not change the glycogen
concentration.)
b) In muscle cells under physiological conditions, the measured ratio of [Pi]/[glucose 1-
phosphate] is more than 100:1. What does this indicate about the direction of metabolite flow
through the glycogen phosphorylase reaction in muscle?
Choose one answer for part a and one answer for part b.
a) [Pi]/[glucose 1-phosphate] = 0.28/1
a) [Pi]/[glucose 1-phosphate] = 0.99/1
a) [Pi]/[glucose 1-phosphate] = 1/1
a) [Pi]/[glucose 1-phosphate] = 3.5/1
Questions & answers rated A+
What two reasons best explain why fats are the primary energy storage molecule compared to
carbohydrates?
Carbohydrates have a higher oxidized state than fats, so the energy yield is lower per gram of
material.
Carbohydrates contain too many glycosidic bonds that can only be hydrolyzed by probiotic
bacteria, fats do not.
Fats are easier to eat because they are tasty, carbs are bland and tasteless so evolution favored
fats over carbs.
There are not two correct answers.
Carbohydrates are hydrated, which adds more wet weight so would be a burden to carry around
carbs.
,Fats have a carboxyl group that helps them to form micelles in the digestive track, whereas
carbs are solid - correct answer ✔✔Carbohydrates have a higher oxidized state than fats, so the
energy yield is lower per gram of material.
Carbohydrates are hydrated, which adds more wet weight so would be a burden to carry around
carbs.
What would be the cost in ATP per glucose residue if glycogen phosphorylase and glycogen
synthase removed and added glucose, respectively, to the ends of glycogen at the same time?
Assume that the glucose used in these reactions comes from glucose-6P. Choose the ONE best
answer - correct answer ✔✔1ATP/glucose residue
The role of glycogenin is to - correct answer ✔✔serve as the origin of the glycogen polymer.
Muscle glycogen phosphorylase is regulated by both allosteric effectors, such as AMP and ATP,
and by hormonal signaling. Allosteric effectors bind to the phosphorylated and
unphosphorylated forms of the enzyme and shift the equilibrium between the inactive T
conformation and the active R conformation. In contrast, hormonal regulation involves
activation of kinase and phosphatase enzymes, which modulate the phosphorylation status of
glycogen phosphorylase.
Which TWO statement(s) below best explain the metabolic logic of this dual regulatory
mechanism? - correct answer ✔✔Allosteric regulation by AMP and ATP provides a way to
quickly shift the activity of muscle glycogen phosphorylase between the active and inactive
states before hormonal signaling is fully stimulated
Both forms of control are important because they work together to ensure maximum
interconversion of glucose and glycogen so that liver cells can maintain safe blood glucose levels
at all times
Put the correct steps required for absorption of dietary fats into order.
,-Entry into the circulatory system
-Emulsification of fats
-Chylomicron assembly
-Export of lipoprotein particle
-Intracellular synthesis of triacylglycerols
-Lipase cleavage - correct answer ✔✔1. Emulsification of fats
2. Lipase cleavage
3. Intracellular synthesis of triacylglycerols
4. Chylomicron assembly
5. Export of lipoprotein particle
6. Entry into the circulatory system
Individuals with McArdle's disease has defects in muscle glycogen phosphorylase. As a result,
individuals with McArdle's disease have an exercise intolerance with fatigue and cramps,
however, after a period of exercise they experience a "second wind" of energy. The second wind
results from cardiovascular adjustments that allow glucose to be mobilized from liver glycogen
to fuel muscle contraction, though this is less efficient.
Choose the ONE best answer below that explains why the amount of ATP derived in the muscle
from circulating glucose is less than the amount of ATP that would be obtained by mobilizing
the same amount of glucose from muscle glycogen.
The production of glucose 6-phosphate from glycogen via the enzyme phosphoglucomutase is
coupled to the formation of ATP. Therefore mobilizing glucose from glycogen results in one
more net ATP made than in the conversion of glucose to lactate via glycolysis. - correct answer
✔✔The conversion of glucose to lactate in muscle generates 2 ATP. If muscle glycogen could be
mobilized, the energy yield would be 3 ATP, since phosphorolysis of glycogen bypasses the
hexokinase-catalyzed step of glycolysis that consumes ATP.
, Starting from a molecule of glucose imported from the blood, what is the energy cost for adding
that molecule of glucose to a growing glycogen chain? - correct answer ✔✔2ATP
Glycogen phosphorylase catalyzes the removal of glucose from glycogen. The ΔGo' for this
reaction is 3.1 kJ/mol.
a) Calculate the ratio of [Pi] to [glucose 1-phosphate] when the reaction is at equilibrium at
298K. (Hint: the removal of glucose units from glycogen does not change the glycogen
concentration.)
b) In muscle cells under physiological conditions, the measured ratio of [Pi]/[glucose 1-
phosphate] is more than 100:1. What does this indicate about the direction of metabolite flow
through the glycogen phosphorylase reaction in muscle?
Choose one answer for part a and one answer for part b.
a) [Pi]/[glucose 1-phosphate] = 0.28/1
a) [Pi]/[glucose 1-phosphate] = 0.99/1
a) [Pi]/[glucose 1-phosphate] = 1/1
a) [Pi]/[glucose 1-phosphate] = 3.5/1
