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NBDE Part 1 > Biochem: Carbohydrates > Flashcards

Biochem: Carbohydrates Flashcards

1
Q

_________ are absorbed by enterocytes in the small intestine.

A

Monosaccharides

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2
Q

What are the three major disaccharides and what are their components?

A

MLS

Maltose = glucose + glucose
Lactose = glucose + galactose
Sucrose = glucose + fructose
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3
Q

T/F: Glycosaminogylcans (GAGs) are repeating disaccharides.

A

True

High viscosity and low compressibility

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4
Q

T/F: GAGs are negatively charged and attract water.

A

True

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5
Q

What is the most abundant GAG?

A

Chondroitin sulfate

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6
Q

What are the only two GAGs that do not end in “sulfate”?

A

Heparin and hyaluronic acid

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7
Q

Why do PGs attract water?

A

Large number of alcohol groups

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8
Q

The central protein in a PG contains which two amino acids?

A

Serine and threonine

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9
Q

Cariogenic bacteria synthesize _______ and ________ from their metabolism of dietary _________.

A

glucans (dextrans); fructans (levans); sucrose

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10
Q

Strep Mutans contains which enzyme that hydrolyzes sucrose to form dextrans (glucans)?

A

glucosyl transferase

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11
Q

T/F: Glycogen is stored in the liver.

A

True

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12
Q

What is the major buffer found in saliva?

A

Bicarbonate

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13
Q

What is the major antibody found in saliva?

A

IgA

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14
Q

Which gland produces the majority of the saliva?

A

Submandibular

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15
Q

During glycolysis glucose gets converted to __________.

A

pyruvate

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16
Q

When oxygen is present, pyruvate will be converted to _________. Without oxygen, pyruvate will be converted to ________.

A

Acetyl-CoA (Kreb’s Cycle); Lactic acid

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17
Q

What three major coenzymes make up the pyruvate dehydrogenase complex?

A
  1. Coenzyme A
  2. NAD
  3. Thiamine
18
Q

What is the function of the pyruvate dehydrogenase complex?

A

To get pyruvate into the mitochondria

19
Q

What is the first step of the citric acid cycle?

A

Citrate synthase converts Acetyl-CoA, Oxaloacetate, and water into citrate

20
Q

What happens to convert pyruvate to Acetyl-CoA?

A

Oxidation by pyruvate dehydrogenase

Glycolysis -> Kreb’s Cycle

21
Q

What happens to convert pyruvate to lactic acid?

A

Reduction by lactate dehydrogenase

Anaerobic

22
Q

What happens to convert pyruvate to oxaloacetate?

A

Carboxylation by pyruvate carboxylase

Gluconeogenesis and replenish TCA cycle

23
Q

What happens to convert pyruvate to alanine?

A

Transamination by alanine aminotransferase

Amino acid synthesis

24
Q

If Acetyl-CoA is not acted on by citrate synthase, what are the other possible routes?

A

Acetyl-CoA is either converted to Malonyl-CoA or HMG-CoA

25
Q

What enzyme converts Acetyl-CoA to Malonyl-CoA?

A

Acetyl-CoA carboxylase

Occurs in cytosol in liver; rate limiting step in fatty acid synthesis

26
Q

What are the two routes for HMG-CoA?

A
  1. Cholesterol synthesis via HMG-CoA reductase

2. Ketone body synthesis via HMG-CoA lyase

27
Q

What are the three major components of gluconeogenesis?

A

LAG

Lactate, amino acids, glycerol

28
Q

What is the net yield of ATP through glycolysis (cytosol)?

A

uses two, makes four

Net = +2

29
Q

What is the net yield of ATP in the TCA cycle (mitochondrial matrix)?

A

Net = +2

30
Q

What is the net yield of ATP in the ETC (inner mitochondrial membrane)?

A

+34

31
Q

What enzyme allows glucose to be brought from the blood into tissue?

A

Hexokinase/glucokinase uses an ATP to convert glucose (blood) to glucose-6-phosphate (tissues)

32
Q

What is the purpose of the pentose phosphate shunt?

A

Produce ribose (DNA synthesis) and NADPH (fatty acid and steroid synthesis)

33
Q

Which part of the nervous system would stimulate glucagon release?

A

Sympathetics

Would result in gluconeogenesis to put glucose into the blood stream

34
Q

Which part of the nervous system would stimulate insulin release?

A

Parasympathetic

35
Q

T/F: Acetyl-CoA is used in gluconeogenesis to make new glucose.

A

False

LAG
Lactate, amino acids, glycerol

36
Q

T/F: Insulin will stimulate glycogenolysis.

A

False

Insulin -> glycogenesis (store glucose)

Glucagon -> glycogenolysis (lyse glycogen to release glucose)

37
Q

What is the goal of the cori cycle?

A

Lactate from muscles is brought to liver to convert to glucose

38
Q

T/F: Glycogen phosphorylase converts glycogen to glucose-1-phosphate.

A

True

Stimulated by glucagon, epinephrine

39
Q

Describe how glucose is converted into glycogen?

A

glucose -> glucose-6-phosphate -> glucose-1-phosphate -> UDP-glucose

Glycogen synthase attaches UDP-glucose to the nonreducing end of glycogen

40
Q

T/F: Ketone bodies can be a source of energy for the brain when in fasting.

A

True

NBDE Part 1 (31 decks)

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