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CMBM E2 CB > Biochemistry > Flashcards

Biochemistry Flashcards

1
Q

Which metabolic activities take place in the mitochondria?

A 
Fatty acid oxidation
Acetyl CoA production
TCA Cycle
Oxidative phosphorylation
Ketogenesis
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2
Q

Which metabolic activities take place in the cytoplasm?

A 
Glycolysis
Fatty acid synthesis
HMP shunt
Protein synthesis (RER)
Steroid synthesis (SER)
Cholesterol synthesis
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3
Q

Which metabolic activities take place in both the mitochondria and the cytoplasm?

A

Heme synthesis
Urea cycle
Gluconeogensis

(HUGs take two)

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4
Q

What is the function of a kinase?

A

Uses ATP to add high-energy phosphate group onto substrate (e.g. PFK)

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5
Q

What is the function of a phosphorylase?

A

Adds inorganic phosphate onto substrate WITHOUT using ATP (e.g. glycogen phosphorylase)

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6
Q

What is the function of a phosphatase?

A

Removes phosphate group from substrate (e.g. fructose-1,6-bisphosphatase)

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7
Q

What is the function of a dehydrogenase?

A

Catalyzes oxidation-reduction reactions (e.g. pyruvate dehydrogenase)

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8
Q

What is the function of a hydroxylase?

A

Adds hydroxyl group onto substrate (e.g. tyrosine hydroxylase)

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9
Q

What is the function of a carboxylase?

A

Transfers CO2 groups with the help of biotin (e.g. pyruvate carboxylase)

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10
Q

What is the function of a mutase?

A

Relocates a functional group within a molecule

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11
Q

What is the rate-determining enzyme of glycolysis?

A

Phosphofructokinase-1

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12
Q

What is the rate-determining enzyme of gluconeogenesis?

A

Fructose-1,6-bisphosphatase

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13
Q

What is the rate-determining enzyme of the TCA cycle?

A

Isocitrate dehydrogenase

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14
Q

What is the rate-determining enzyme of glycogenesis?

A

Glycogen synthase

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15
Q

What is the rate-determining enzyme of glycogenolysis?

A

Glycogen phosphorylase

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16
Q

What is the rate-determining enzyme of the HMP shunt?

A

Glucose-6-phosphate dehydrogenase (G6PDH)

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17
Q

What is the rate-determining enzyme of the urea cycle?

A

Carbamoyl phosphate synthetase I

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18
Q

What is the rate-determining enzyme of fatty acid synthesis? What cofactor is required?

A

Acetyl-CoA carboxylase

Requires biotin

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19
Q

What is the rate-determining enzyme of fatty acid oxidation?

A

Carnitine acyltransferase I

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20
Q

What is the rate-determining enzyme of ketogenesis?

A

HMG-CoA synthase

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21
Q

What is the rate-determining enzyme of cholesterol synthesis?

A

HMG-CoA reductase

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22
Q

What are the regulators of glycolysis?

A

+ AMP
+ fructose-2, 6-bisphosphate
- ATP
- citrate

23
Q

What are the regulators of gluconeogenesis?

A

+ ATP
+ acetyl CoA
- AMP
- fructose-2, 6-bisphosphate

24
Q

What are the regulators of the TCA cycle?

A

+ ADP

  • ATP
  • NADH
25
Q

What are the regulators of glycogenesis?

A 
\+ glucose-6-phosphate
\+ insulin
\+ cortisol
- epinephrine
- glucagon
26
Q

What are the regulators of glycogenolysis?

A 
\+ epinephrine
\+ glucagon
\+ AMP
- glucose-6-phosphate
- insulin
- ATP
27
Q

What are the regulators of the HMP shunt?

A

+ NADP

- NADH

28
Q

What regulates the urea cycle?

A

+ N-acetylglutamate

29
Q

What are the regulators of fatty acid synthesis?

A

+ Insulin
+ Citrate
- Glucagon
- Palmitoyl-CoA

30
Q

What regulates fatty acid oxidation?

A
  • Malonyl-CoA
31
Q

What are the regulators of cholesterol synthesis?

A

+ Insulin
+ Thyroxine
- Glucagon
- Cholesterol

32
Q

Which process produces NADPH? What is it generally used for?

A

HMP shunt

NADPH is used in:
Anabolic processes
Respiratory burst
Cytochrome P-450 system
Glutathione reductase
33
Q

What are the different fates of pyruvate?

A
  1. Oxidatively decarboxylated by pyruvate dehydrogenase, producing acetyl CoA
  2. Carboxylated to oxaloacetate by pyruvate carboxylase
  3. Reduced by microorganisms to ethanol by pyruvate decarboxylase
34
Q

What is the most common genetic defect of glycolytic enzymes?

A

Pyruvate kinase deficiency

35
Q

What are the two most common causes of enzyme deficiency-related hemolytic anemia?

A
  1. G6PDH deficiency

2. Pyruvate kinase deficiency

36
Q

What is the sole source of fuel for red blood cells?

A

Glucose

37
Q

During the fasting state, which process plays the primary role in maintaining blood glucose levels? Which process continues the maintenance?

A

Glycogenolysis, followed by gluconeogenesis

38
Q

How do fatty acids provide fuel during the fasting state?

A

They are oxidized to acetyl CoA and subsequently to CO2 and H2O in the TCA Cycle, producing energy in the form of ATP.

39
Q

What are the carbon sources for gluconeogenesis?

A

Lactate (from red blood cells)
Glycerol (from TAG degradation in adipose cells)
Amino acids (from muscle protein degradation)

40
Q

What serves as the body’s major fuel during fasting?

A

Fatty acids (released from adipose tissue via lipolysis)

41
Q

When does ketogenesis take over as the body’s main fuel supply?

A

After fasting for about 3 days.

The liver releases ketones derived from fat oxidation as an alternative fuel source for the brain. Liver glycogen stores are depleted and gluconeogenesis provides glucose to the body.

42
Q

What do adipose cells provide during the fasting state?

A

Adipose cells degrade TAGs, which supply FAs for energy and glycerol for gluconeogenesis.

43
Q

What is the major source of blood glucose 24 hours after a meal?

A

Hepatic gluconeogenesis (liver glycogen nearly depleted by this time)

44
Q

What is the function of biotin in fatty acid synthesis?

A

Acts as a cofactor for rate-determining Acetyl CoA carboxylase. Typically acts as a CO2 carrier/activator. Biotin is linked to the enzyme between the terminal carboxyl of the biotin side chain and the e-amino group of a lysine residue.

45
Q

In fatty acid synthesis, what is the final step and which enzyme is involved?

A

Fatty acids are added two at a time until C16 palmitoyl is formed. In the final step, this is converted to palmitate by a thioesterase.

46
Q

How is fatty acid synthase regulated?

A

At the transcriptional level

47
Q

What are the only purely ketogenic amino acids?

A

Lysine and leucine

48
Q

What is the difference between substrate level and oxidative phosphorylation?

A

Substrate-level phosphorylation is directly phosphorylating ADP with a phosphate and energy provided from a coupled reaction. SLP will only occur if there is a reaction that releases sufficient energy to allow the direct phosphorylation of ADP.

Oxidative phosphorylation is when ATP is generated from the oxidation of NADH and FADH2 and the subsequent transfer of electrons and pumping of protons. That process generates an electrochemical gradient, which is required to power the ATP synthase.

49
Q

What supplies the two-carbon units that are added to the elongating fatty acid chain?

A

Malonyl CoA

50
Q

What is the net yield of oxidizing palmitic acid?

A

106 ATP

51
Q

How do ketone bodies connect to the TCA cycle?

A

Via succinyl-CoA

52
Q

What ratio regulates the equilibrium of ketone bodies in the blood?

A

NAD+ / NADH

53
Q

What percentage of cholesterol is esterified and therefore harder to get into a cell?

A

65%

54
Q

What percentage of the fat you ingest is absorbed?

A

95% regardless of how much or how little you eat

CMBM E2 CB (6 decks)

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