WorksheetsMetabolic Pathways (CARBS)
Total questions: 83
Worksheet time: 2hrs 19mins
Write: I am going to ace this test three times.
Explain the metabolism of fructose. Everything you can remember: where it happens, enzymes involved, etc
True or false? If concentrations of fructose is high, then fructose can be metabolized in the muscle by hexokinase.
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In the liver, fructose is phosphorylated by (a) to fructose-1-phosphate.
In the liver, after fructose is phosphorylated to fructose-1-phosphate by fructokinase, it can be converted to (a) and enter glycolysis at step 4 or 5.
Why can overconsumption of fructose lead to fatty liver disease and hyperlipidemia?
Describe how overconsumption of fructose could lead to gout.
True or False? In the muscle, fructose is phosphorylated to fructose-6-phosphate by enzyme (a) .
Describe the metabolism of galactose.
Galactose is phosphorylated to Galactose-1-phosphate by enzyme (a) .
Galactose is phosphorylated to Galactose-1-phosphate by enzyme galactokinase. Next, galactose-1-phosphate is converted to (a) .
What can happen to glucose-1-phosphate (derived from the metabolism of galactose)?
Be converted to glycogen and stored in the liver
Be converted to uric acid and lead to gout
Be converted to glucose-6-phosphate and enter glycolysis
Be converted to free glucose
What are the three irreversible steps of glycolysis?
Step 1: phosphorylation of glucose
Step 3: fructose-6-phosphate to fructose-1,6-biphosphate
Step 5: Creation of glyceraldehyde-6-phosphate
Step 10: Pep converted to pyruvate
What's the starting material for glycolysis?
1, 6-C Glucose
2 ATP
2 NAD+
1 FAD
What enzyme(s) are responsible for step one of glycolysis (glucose --> glucose-6-phosphate)?
glucose dehydrogenase
Hexokinase
glucokinase
hexose-dehydrogenase
Hexokinase and glucokinase are both enzymes involved with step one of glycolysis. Which one is active in the liver and pancreatic beta cells?
Hexokinase
Glucokinase
True or False? Both Hexokinase and glucokinase are allosterically inhibited by glucose-6-phosphate.
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What's the difference between glucokinase and hexokinase? (Where are they active, How does Km, Vmax, and affinity compare to each other? How are they inhibited?)
Step __ of glycolysis traps glucose in the cell.
1
3
5
10
In step 3 of glycolysis, fructose-6-phosphate is converted to fructose-1,6-biphosphate by the enzyme (a) .
In step 3 of glycolysis, fructose-6-phosphate is converted to fructose-1,6-biphosphate by the enzyme PFK1 (phosphofructokinase 1). This is an important regulatory step and is positively allosterically modulated by:
ATP
AMP
ADP
Citrate
In step 3 of glycolysis, fructose-6-phosphate is converted to fructose-1,6-biphosphate by enzyme PFK 1 (phosphofructokinase 1). This is an important regulatory step and is negatively allosterically modulated by:
ATP
ADP
AMP
Citrate
In step 3 of glycolysis, fructose-6-phosphate is converted to fructose-1,6-biphosphate by PFK1. This is an important regulatory step and is also known as the committed step of glycolysis. Therefore, PFK1 is allosterically regulated by (+) AMP, (+) ADP, (-) ATP, and (-) Citrate. However, in the liver there is an override switch. Explain the override switch.
Which two steps of glycolysis require ATP to proceed?
Step 1
Step 3
Step 4
Step 10
In step 10, the last step of glycolysis, PEP is converted to pyruvate by the enzyme (a) .
Which glycolytic enzyme is subject to the most genetic mutations?
Glucokinase
Hexokinase
PFK1
Pyruvate Kinase
How is pyruvate kinase regulated?
What are the products of glycolysis?
True or false? Alanine can be converted to pyruvate and become a starting material for pyruvate dehydrogenase.
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What enzyme is needed for the pyruvate dehydrogenase reaction?
(a)
What are the products of pyruvate dehydrogenase?
True or false? The pyruvate dehydrogenase complex is LESS active when it is dephosphorylated.
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F
What inhibits the pyruvate dehydrogenase complex?
(a)
Where does pyruvate dehydrogenase happen within the cell? (And how does it get there?)
True or false? Pyruvate dehydrogenase is reversible.
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The Kreb's cycle is an (a) reaction, involving both catabolic and anabolic reactions.
The starting material for the Kreb's cycle is...
Explain how you can get oxaloacetate from pyruvate dehydrogenase?
In the mitochondrial matrix, (a) can convert pyruvate to oxaloacetate, requiring biotin as a coenzyme.
True or false? Aceyl-CoA is a positive modulator for pyruvate carboxylase, the enzyme responsible for converting pyruvate to oxaloacetate.
Yep, straight true. No cap.
Cap
What happens when the body does not have enough oxaloacetate?
In step one of Kreb's, citrate is formed from the combination of oxaloacetate and acetyl-CoA. What is the enzyme responsible?
(a)
In step 3 of Kreb's, isocitrate is converted to alpha-ketoglucerate by the enzyme (a) .
In step 3 of Kreb's, isocitrate is converted to alpha-ketoglucerate by the enzyme isocitrate dehydrogenase. Isocitrate dehydrogenase is positively modulated by:
ADP
ATP
CALCIUM
NADH
In step 3 of Kreb's, isocitrate is converted to alpha-ketoglucerate by the enzyme isocitrate dehydrogenase. Isocitrate dehydrogenase is negatively modulated by:
ATP
ADP
CALCIUM
NADH
In step 8 of Kreb's, malate is converted to oxaloacetate by the enzyme (a) .
Malate dehydrogenase is negatively modulated by...
NAD
NADH
What are the products of the Kreb's cycle (per glucose?)
Your Aunt Jane has heard from her friend that cancer cells metabolize glucose differently than normal cells. Your aunt wants you to explain to her the difference in glucose metabolism between normal and cancer cells.
Your Aunt Jane has heard from her friend that cancer cells metabolize glucose differently than normal cells. She also heard her talking about the ‘Warburg effect’. Your aunt wants you to explain to her what the ‘Warburg’ effect is.
(a) is affected in cancer cells. It produces a biproduct that can be used for the growth of the cancer cell instead of the formation of energy. hint: it's the enzyme involved in step 10 of glycolysis.
Explain how the glycosidic inhibitor, DCA, works.
Compare and contrast the two NADH shuttle systems: Malate-Aspartate system and Glycerol-3-phosphate system.
True or False? Pyruvate dehydrogenase kinase catalyzes the phosphorylation and activation of the pyruvate dehydrogenase complex.
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F
True or false? Glycosidic bonds connect sugar molecules in both linear and branches of complex carbohydrates.
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F
True or False? The committed step of the glycolytic pathway is catalyzed by hexokinase.
T
F
True or False? The Hexose Monophosphate Shunt happens in the fasting state.
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F
The Hexose Monophosphate pathway starts with glucose-6-phosphate and ends with NADPH and Pentose Phosphates. What is NADPH used for?
True or False? There is more glycogen stored in muscle than in the liver.
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F
Although the majority of glycogen is stored in muscle tissue, this glucose cannot be shared with peripheral tissues because muscle cells lack the enzyme (a) .
The phosphorylation of glucose to glucose-6-phosphate is the first step, not only in the glycolysis pathway, but also in the glycogenesis pathway. In the muscle cells, the enzyme responsible is hexokinase, which is negatively modulated by (a) . In the liver cells, the enzyme glucokinase is responsible for this transformation, but it is not negatively modulated by that substrate.
UDP-glucose is incorporated into preform glycogenin primer to create unbranched glycogen. This is catalyzed by the enzyme (a) .
True or false? Insulin activates glycogen synthase.
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Glycogenesis consumes ATP (rxn 1) and _ UTP (rxn 3) for each glucose molecule. (Submit answer as X;X)
(a)
This hormone stimulates glycogenolysis in the liver and adipose tissue.
insulin
glucagon
hexokinase
epinephrine
Fill out this chart.
In glycogenolysis, the glycosidic bonds are cleaved through (hydrolysis/phosphorolysis).
(a)
This enzyme in glycogenolysis cleaves alpha 1,4 glycosidic bonds.
(a)
Explain the regulation of glycogen phsophorylase. (Active form, Allosteric Modulation, Covalent Modulation).
What are the steps of glycogenolysis and the key enzymes of these steps?
Explain how glycogenolysis is triggered in muscle tissue.
Explain the modification (activation, deactivation) of glycogenolysis in the liver.
In this glycogen storage disease, there is a defect in the enzyme glucose-6-phosphatase. This leads to an increased amount of glycogen stored in the liver and kidney. This leads to massive enlargement of the liver, severe hypoglycemia, ketosis, among others.
Pompe's disease
Von Geirke's Disease
Galactosemia
McArdle Disease
In Pompe's disease, lysosomal alpha 1,4 glucosidase is defective. This leads to an increased amount of glycogen storage, cardiorespiratory failure, and death, usually before the age of 2. Which organ systems are affected?
Heart
Liver
Kidneys
All organs
In Cori, a glycogen storage disease, amylo-1,6-glucosidase is the defective enzyme. This affects glycogen in the liver and muscles, but HOW, I ask?
Just more of it
Less of it
Increased amount AND shorter branches
Increased amount AND longer branches
This enzyme is deficient in McArdle disease.
glucose-6-phosphatase
alpha 1,4 glucosidase
amylo 1,6 glucosidase
phosphorylase
What happens if there is a defect in the hexose monophosphate shunt in RBC?
What is the role of glucose-6-phosphate dehydrogenase in the hexose monophosphate shunt pathway?
What are substrates for gluconeogenesis?
What are some important enzymes for gluconeogensis? Where are they located within the cell? What do they do?
How does glucagon regulate gluconeogensis?
True or false? muscle and adipocytes can preform gluconeogenesis.
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Describe the different stages of glucose homeostasis through phases of starvation.
