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Biochemistry II Final > Alcohol Metabolism > Flashcards

Alcohol Metabolism Flashcards

0
Q

How much energy per gram does alcohol provide?

A

7kcal/gram

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1
Q

What are the consequences of alcoholism?

A

Fatty liver, hepatic disease (cirrhosis), and lactic acidosis

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2
Q

Does alcohol possess any nutrients?

A

No

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3
Q

Where is ethanol readily absorbed?

A

Throughout the entire GI tract

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4
Q

Where is ethanol primarily degraded?

A

In the liver

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5
Q

The liver converts ethanol into what?

A

Acetaldehyde then to acetate

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6
Q

Both steps of conversion of ethanol to acetaldehyde then to acetate in the liver produce what?

A

NADH

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7
Q

What can acetate possibly turn into next?

A

Acetyl CoA

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8
Q

What are the three enzyme systems that break down alcohol?

A

Alcohol dehydrogenase, MEOS (microsomal ethanol oxidizing system aka Cytochrome P-450 System), and catalase

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9
Q

What is the least active enzyme system for the breakdown of alcohol?

A

Catalase

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10
Q

What is used in the presence of catalase for alcohol breakdown?

A

Hydrogen peroxide

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11
Q

What enzyme is responsible for oxidizing ethanol into acetaldehyde?

A

Alcohol dehydrogenase

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12
Q

What enzyme is responsible for oxidizing acetaldehyde into acetate?

A

Acetaldehyde dehydrogenase

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13
Q

NADPH is produced in which enzyme systems for alcohol breakdown?

A

Both alcohol dehydrogenase AND MEOS

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14
Q

What is the location of the alcohol dehydrogenase pathway?

A

Cytoplasm of liver cells

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15
Q

What is required for alcohol dehydrogenase to work?

A

NAD

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16
Q

At what point is alcohol dehydrogenase at 1/2 maximum velocity?

A

At cellular concentration of ethanol

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17
Q

At what point is alcohol dehydrogenase saturated?

A

At 3-4 times the Km

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18
Q

At what point can alcohol no longer be oxidized by alcohol dehydrogenase?

A

Concentrations beyond 4 times Km

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19
Q

What is the toxic level of alcohol?

A

50-100 mg/dL

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20
Q

What is the reason that ethanol is able to enter the cells easily?

A

High lipid solubility

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21
Q

When alcohol dehydrogenase is saturated, what enzyme system must take over for breakdown of alcohol?

A

MEOS

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22
Q

Which gender’s alcohol dehydrogenase is less effective?

23
Q

Having a lot of NADPH in the system due to alcohol metabolism can inhibit and affect what pathways?

A

Fat burning, gluconeogenesis, and Krebs

24
Q

What types of compounds can MEOS oxidize?

A

Fatty acids, aromatic hydrocarbons, steroids, barbiturate drugs

25
Q

The MEOS system is associated with what location of the cell?

A

Endoplasmic reticulum

26
Q

With MEOS, where are the electrons coming from to be donated to the P450?

A

From NADPH

27
Q

What two things are added to the ethanol during the first step of MEOS to change it to acetaldehyde?

A

Electrons from NADPH and oxygen

28
Q

Does MEOS directly produce NADH?

A

No; it creates acetaldehyde which eventually leads to the production of NADH indirectly

29
Q

What is known as being the “microsomal electron transport system”?

30
Q

MEOS is also known as what?

A

Cytochrome P-450 Monooxygenase System

31
Q

Ethanol in high concentrations can have what effect on the enzymes of MEOS?

A

The enzymes are inducible & synthesis of them occurs (alcohol tolerance)

32
Q

What can acetaldehyde attach to and impede its activity?

A

Enzymes (overall: covalently attaches to proteins creating protein adducts)

33
Q

What effect does acetaldehyde attaching to proteins have on the liver?

A

Impedes the formation of microtubules in the liver

34
Q

What can the accumulation of protein adducts due to acetaldehyde covalently bonding to proteins lead to?

A

Perivenular fibrosis

35
Q

What as originally thought to be the cause of cirrhosis of the liver?

A

Malnutrition

36
Q

Can alcoholism lead to cirrhosis of the liver without malnutrition?

A

Yes; nutrition is not a factor as once previously thought

37
Q

Where can fat accumulate due to ethanol metabolism?

A

Liver, myocardium, renal tubules

38
Q

What lipid pathway is stimulated with ethanol metabolism?

A

Fat synthesis

39
Q

How is the Krebs cycle affected by alcohol metabolism?

40
Q

What accumulates in the Krebs cycle due to the the inhibiting effect from alcohol metabolism?

41
Q

What pathway does the accumulation of citrate from the Krebs cycle lead to?

A

Fat synthesis

42
Q

What enzyme for TAG synthesis is stimulated by alcohol metabolism?

A

Glycerol 3-phosphate dehydrogenase

43
Q

What enzyme in glycolysis can be inhibited by alcohol metabolism?

A

Glyceraldehyde 3-phosphate dehydrogenase

44
Q

What enzyme in glycolysis is stimulated with alcohol metabolism?

A

Lactate dehydrogenase

45
Q

What is the negative effect of the stimulation of lactate dehydrogenase in glycolysis due to alcohol metabolism?

A

Overproduction of lactic acid (leading to lactic acidosis)

46
Q

During fat accumulation due to alcohol metabolism, what is converted into glycerol?

47
Q

What effect does alcohol metabolism have on gluconeogenesis?

A

Inhibition

48
Q

What ratio is important during alcohol metabolism to determine the effects on other pathways?

49
Q

When alcohol dehydrogenase is saturated, which enzyme therefore becomes inducible because it is needed to further metabolize ethanol?

50
Q

What effect does excess NADH (ethanol metabolism) have on fat synthesis?

A

Stimulation

51
Q

What effect does excess NADH (ethanol metabolism) have on lactic acid buildup?

A

Stimulation

52
Q

What effect does excess NADH (ethanol metabolism) have on TCA?

A

Inhibition

53
Q

What effect does excess NADH (ethanol metabolism) have on fat burning?

A

Inhibition

54
Q

What reactions of Krebs are inhibited by the ethanol metabolism pathway?

A

Dehydrogenase reactions

Biochemistry II Final (5 decks)

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