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NPLEX - Biochemistry > Carbohydrates > Flashcards

Carbohydrates Flashcards

1
Q

Does insulin induce or activate glucokinase? Does insulin induce or activate PFK-2?

A

induces glucokinase in liver cells

activates PFK-2 by dephosphorylating it

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2
Q

Via which complex do the electrons from NADH enter the ETC? How do the electrons from FADH2 enter the ETC?

A

complex I

complex II

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3
Q

Name the linkage that iso-maltase cleaves.

A

alpha-1,6 glycosidic linkage

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4
Q

Where are the bulk of dietary sugars absorbed?

A

duodenum and upper jejunum

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5
Q

Glycolysis occurs in which part of the cell?

A

cytoplasm

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6
Q

What are the important enzymes of the HMP shunt (aka pentose phosphate pathway)?

A

glucose-6-P dehydrogenase and transketolase

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7
Q

Which enzyme complex in the Krebs cycle requires cofactors?

A

alpha-ketoglutarate dehydrogenase

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8
Q

If galactokinase is impaired, what happens?

A

galactose builds up in the blood and spills in the urine, but there is no build up of the toxic compound galactose-1-P

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9
Q

How many carbons are in a heptose?

A

7

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10
Q

What are the three necessary cofactors for all carboxylases?

A

ATP, biotin, and carbon dioxide

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11
Q

Is the pentose phosphate pathway (aka HMP shunt) reversible?

A

yes, controlled by metabolic needs of cell

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12
Q

Which enzyme converts glucose to glucose-6-P?

A

hexokinase or glucokinase in combination with ATP converts glucose to glucose-6-P

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13
Q

What two types of tissue produce lactate most frequently?

A

muscles (working anaerobically)

RBCs (no mitochondria)

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14
Q

Name two positive and three negative regulators of citrate synthase.

A

+ acetyl CoA, OA

  • NADH, fatty acyl CoA, succinyl CoA
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15
Q

Name the monosaccharide that is a constituent found in glycoproteins and in plants gums.

A

mannose

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16
Q

Name the four kinases in glycolysis. Which are reversible and which are irreversible?

A

hexokinase, phosphofructokinase, and pyruvate kinase are controlled enzymes that catalyze irreversible steps in glycolysis

phosphoglycerate kinase catalyzes a reversible step

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17
Q

Where do the RBCs and brain cells get their glucose from between meals?

A

liver

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18
Q

Which polysaccharide that has glucose molecules bound by beta-1,4 linkages and is not able to be broken down by most animals?

A

cellulose

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19
Q

Which enzyme in the liver converts glucose-6P to glucose?

A

glucose-6-P phosphatase

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20
Q

What enzyme is responsible for the buildup of galactose products in the lens?

A

aldose reductase

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21
Q

What is the significance of the first half of the HMP shunt? Second half?

A

production of NADPH

production of ribose-5-P

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22
Q

T/F: lactose uses the anomeric carbon of both sugars and has no mutorotation.

A

F

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23
Q

Where does the body obtain the alanine used to make pyruvate via gluconeogenesis between meals?

A

it is the result of protein breakdown in muscle tissue

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24
Q

Name the enzyme involved in the conversion of pyruvate to acetyl-CoA.

A

pyruvate dehydrogenase

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25
Q

Where is 2,3-BPG made?

A

in the RBC by the conversion of the glycolysis intermediate 1,3-BPG to 2,3-BPG

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26
Q

Name the polysaccharide that is made up of repeating fructose molecules and is a starch found in many roots. It is also excreted in the urine with no resorption in the renal tubules.

A

inulin

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27
Q

Where do the electrons go from cytochrome C?

A

complex IV (aka cytochrome oxidase)

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28
Q

Name the three biochemical pathways by which insulin increases glucose use.

A

oxidation (facilitates glucose entry into glycolytic pathway)

glycogenesis

lipogenesis

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29
Q

Where is glucokinase found?

A

liver

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30
Q

What is the function of PEPCK?

A

converts OAA to PEP

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31
Q

How many ATPs are produced in aerobic glucose metabolism, assuming mitochondria are available?

A

38 via malate shuttle: 36 via G3P shuttle

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32
Q

What is the net gain of ATP per glucose molecule in the TCA cycle?

A

12 per cycle of the TCA -> 24 per glucose

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33
Q

Name the three proton pumps located in the inner mitochondrial membrane.

A

complex I, III, IV

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34
Q

In sucrose, carbon 1 of glucose is attached to carbon __ of fructose?

A

carbon 2

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35
Q

What are the inhibitors of glycogen synthase in liver and muscle?

A

glucagon and epinephrine in the liver

epinephrine in muscle

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36
Q

Human salivary amylase breaks down which type of linkage?

A

alpha-1,4 linkage

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37
Q

Glucagon activates (protein kinase/protein phosphatase) which promotes (glycogen synthesis/glycogenolysis).

A

protein kinase

glycogenolysis

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38
Q

What tissues contain the pentose phosphate pathway (aka HMP shunt)?

A

liver, mammary tissue, adrenal cortex, RBC

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39
Q

What is the first step in the metabolism of galactose?

A

galactokinase produces galactose-1-P

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40
Q

What is the main sugar-regulating hormone secreted in the post-absorptive state (between meals)?

A

glucagon

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41
Q

Which complex in the ETC does cyanide inhibit?

A

complex IV (aka cytochrome oxidase)

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42
Q

What will happen in aldolase B is impaired?

A

fructose-1-P will build up in the liver

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43
Q

Which disaccharide has two glucose units?

A

maltose

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44
Q

Describe the functions of cortisol on sugar, fat and protein metabolism.

A

stimulates gluconeogenesis in the liver

mobilizes amino acids from extrahepatic tissue

inhibits glucose uptake in muscle and adipose

stimulate lipolysis

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45
Q

What is the common name of glucose (alpha-1, beta-1)-fructose?

A

sucrose

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46
Q

What are the three substrates for gluconeogenesis?

A

alanine, lactate, and glycerol-3-P

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47
Q

What is the function of glycogen phosphorylase?

A

it will break alpha-1,4 bonds to release glucose-1-P until it encounters the first branch point

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48
Q

Name the reactions in glycolysis and the TCA cycle which produce NADH.

A

Glycolysis: glyceraldehyde-3-P dehydrogenase and pyruvate dehydrogenase

Krebs: isocitrate dehydrogenase, alpha-ketoglutarate dehydrogenase, malate dehydrogenase

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49
Q

Trace the pathway whereby insulin can activate PFK-1.

A

insulin activates PFK-2 by causing it to become dephosphorylated.

PFK-2 then converts fructose-6-P to fructose-2,6-bisP

Fructose-2,6-bisP activates PFK-1

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50
Q

Name five important polysaccharides.

A

amylose, amylopectin, glycogen, inulin, cellulose

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51
Q

Describe the activity of debranching enzyme.

A

debranching enzyme breaks the alpha-1,4 bond nearest the branch point and transfers the oligoglucose unit to the end of another chain.

It then goes back and hydrolyzes the alpha-1,6 bond, releasing a single glucose

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52
Q

Are galactose and mannose epimers or are they just isomers?

A

isomers

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53
Q

Where does acetyl-CoA get produced?

A

mitochondrial matrix

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54
Q

Is a five membered ring with four carbons and one oxygen a pyranose or furanose?

A

furanose

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55
Q

Which glands secrete the enyzymes in the small intestine that hydrolyze disaccharides on the brush border?

A

Brunner and Lieberkuhn glands

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56
Q

What is the rate limiting step of glycolysis?

A

conversion of fructose-6P to fructose-1,6-bisphosphate by PFK-1

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57
Q

Where does the breakdown of sucrose occur? Which enzyme is responsible?

A

sucrase (aka invertase) will split sucrose into glucose and fructose in the jejunum

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58
Q

In lactose, carbon one of glucose is attached to carbon ___ of glucose.

A

lactose is formed by a glycosidic bond between C1 of galactose and C4 of glucose

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59
Q

To activate pancreatic enzymes, does the pH need to be raised or lowered?

A

alkalinization (raising the pH) is needed to activate pancreatic enzymes to work effectively

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60
Q

Glucose-6-P dehydrogenase deficiency: What molecule is decreased if this enzyme is inactive?

A

NADPH

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61
Q

What are the four unique enzymes of gluconeogenesis (that are not also used in glycolysis)?

A

pyruvate carboxylase, PEP carboxykinase, fructose-1-6-bisphosphatase, glucose-6-phosphatase

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62
Q

Name the linkages that maltase cleaves.

A

glycogen alpha 1,4 glycosidic linkages

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63
Q

Which complex of the ETC does NADH give its electrons to?

A

complex I (aka NADH dehydrogenase)

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64
Q

If the oxygen on the anomeric carbon (carbonyl group) of a sugar is not attached to any other structure, is this a reducing or non-reducing sugar?

A

reducing sugar

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65
Q

Which cytochrome contains bound copper atoms? What complex is this cytochrome part of?

A

cytochrome A/A3, located in complex IV (aka cytochrome oxidase)

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66
Q

What are the main cells that fructose is used in?

A

liver, kidney cells

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67
Q

How does the ATP get out of mitochondria after it is produced?

A

it is exchanged for ADP through ATP/ADP translocase

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68
Q

Name three common disaccharides.

A

sucrose (glucose + fructose), lactose (glucose + galactose), maltose (glucose + glucose)

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69
Q

Where does the Krebs cycle take place?

A

mitochondria

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70
Q

What is the key limiting step in gluconeogenesis?

A

PEPCK

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71
Q

How much CO2, NADH, QH2, and GTP are created from each acetyl-CoA that enters the Krebs cycle?

A

one GTP (or ATP)

3 NADH

1 QH2

2 CO2

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72
Q

Which enzyme has a lower Km for glucose: hexokinase or glucokinase?

A

hexokinase

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73
Q

What is the chemical formula for glucose?

A

C6H12O6

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74
Q

Which two steps does galactose have to go through to enter glycolysis?

A

galactokinase turns galactose into galactose-1-P

galactose-1-P uridyl transferase turns galatose-1-P into glucose-1-P

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75
Q

Where do the proton pumps in the ETC pump protons to?

A

they pump protons across the inner mitochondrial membrane into the intermembrane space

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76
Q

Carbohydrates with an aldehyde as their most oxidized functional group are called?

A

aldoses

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77
Q

Which polysaccharide contains alpha-1,4 glycosidic linkages, and has branch points with alpha-1,6 glycosidic linkages?

A

amylopectin

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78
Q

Name the three products that glucose-6-phosphate can be converted to.

A

glucose-1-P (glycogen pathway)

fructose-6-P (TCA)

6-phosphogluconolactone (ribose-5-phosphate pathway)

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79
Q

What is the treatment for someone with a galactose metabolism enzyme deficiency?

A

complete restriction of galactose-containing products (dairy)

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80
Q

Name the sugars that are C2 epimers.

A

glucose and mannose

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81
Q

Which molecules directly trigger the breakdown of glycogen in the liver and in muscle?

A

glucagon triggers breakdown in liver

EPI controls breakdown in liver and muscle

AMP controls breakdown in muscle

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82
Q

How is NAD in a RBC replenished?

A

lactate dehydrogenase

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83
Q

Where do the electrons coming in from FADH2 go?

A

directly to coenzyme Q (aka ubiquinone), bypassing complex I

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84
Q

Name the 8 steps of the TCA.

A

acetyl-CoA to citrate to isocitrate to alpha-ketoglutarate to succinyl-CoA to succinate to fumarate to malate to oxaloacetate

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85
Q

In oxidative phosphorylation, on what side of the mitochondrial membrane is ATP produced?

A

mitochondrial matrix

86
Q

In which enzymes of galactose metabolism are deficiencies most commonly found?

A

deficiencies in galactokinase and galactose-1-phosphate uridylyltransferase (aka GALT) are MC

87
Q

What is the most complicated step of gluconeogenesis?

A

conversion of pyruvate to PEP

88
Q

Name the three drugs that inhibit complex IV?

A

cyanide, carbon monoxide, azide

89
Q

Which enzyme converts fructose-6-P to fructose-1,6-bis-P?

A

phosphofructokinase (rate limiting step of glycolysis)

90
Q

Which storage molecule is similar to amylopectin in structure, but is more highly branched?

A

glycogen

91
Q

What is the common name for galactose (beta 1,4) - glucose?

A

lactose

92
Q

When is the use of lactate dehydrogenase essential to replenish the NAD?

A

when the ETC is not working (lack of oxygen) or not present dt lack of mitochondria (RBC)

93
Q

Name four intermediates of the Krebs cycle that can be used in other pathways.

A

citrate (FA synthesis)

succinyl CoA (heme synthesis)

fumarate (urea cycle)

malate (gluconeogenesis)

94
Q

What enzyme is required for alanine to be used in gluconeogenesis?

A

alanine transaminase

95
Q

NADH feeds back on which three control points of the Krebs cycle?

A

isocitrate dehydrogenase, citrate synthase, alpha ketoglutarate dehydrogenase

96
Q

Name the non-branching polysaccharide comprised of alpha-1,4 glycosidic linkages that forms a helical or coil shape.

A

amylose

97
Q

Glucose-6-P dehydrogenase deficiency: What cells are most sensitive to this kind of damage?

A

RBCs

98
Q

What is the rate limiting step for glycolysis?

A

PFK-1 conversion of fructose-6-P to fructose-1,6-bis-P

99
Q

Glucagon phosphorylates PFK-2, which turns glycogen synthase __ and turns phosphorylase __.

A

off

on

100
Q

Which polysaccharide has beta-1,4 glycosidic linkage?

A

cellulose

101
Q

What is the only enzyme deficiency in glycolysis that is clinically relevant?

A

pyruvate kinase

102
Q

What are the two enzymes involved in the breakdown of glycogen?

A

glycogen phosphorylase and debranching enzyme

103
Q

What happens to glucose-1-P?

A

converted to glucose-6-P (glycolysis) or it can be added to glycogen (glyconeogenesis)

104
Q

Insulin activates (protein kinase/protein phosphatase) which promotes (glycogen synthesis/glycogenolysis).

A

protein phosphatase

glycogen synthesis

105
Q

Which substrates do not produce NADH or FADH2 as they go through the Krebs cycle?

A

citrate, succinyl-CoA, fumarate, oxaloacetate

106
Q

What is the clinical significance of transketolase?

A

thiamine-requiring enzyme that used to test the thiamine levels in people

107
Q

Which polysaccharide contains alpha-1,4 glycosidic linkages and branch points that contain alpha-1,6 glycosidic linkages?

A

amylopectin

108
Q

Describe the activity of branching enzyme. Where does it break and form bonds?

A

it break alpha-1,4 bonds about 6-8 glucose molecules from the end

after breaking of the end of the chain it goes back about four glucose molecules on the original chain and then make an alpha-1,6 bond to create a branch

109
Q

What is fructose-6-P converted to and what is required for this?

A

fructose-1,6-bisphosphate by PFK-1 and ATP

110
Q

How does cytoplasmic NADH enter the mitochondria?

A

it doesn’t

it uses the malate or glycerol-3-P shutle to transfer electrons into the mitochondria

111
Q

Name the hormone that favors the breakdown of liver and muscle glycogen and decreases the release of insulin via production of cAMP.

A

EPI

112
Q

What type of bonds does glycogen synthase make?

A

alpha-1,4 bonds

113
Q

What happens if galactose-1-P uridyl transferase is impaired?

A

galactose builds up into the blood and spills into the urine

there is a build-up of the toxic metabolic galactose-1-P

114
Q

During oxidative phosphorylation, how do protons get moved into the mitochondrial matrix?

A

the protons pass through the F0 subunit of the ATP synthase enzyme (complex V)

115
Q

Where is hexokinase found?

A

throughout the body (muscle, RBC, brain)

116
Q

Does hexokinase have a high or low affinity for glucose?

A

very high

117
Q

What is the mechanism of oligomycin inhibition of ATP synthase?

A

oligomycin prevents the influx of protons through ATP synthase, effectively shutting down ETC.

118
Q

What enzyme converts 1,3-BPG to 2,3-BPG?

A

bisphosphoglycerate mutase (in RBC)

119
Q

Name two negative regulators of alpha dehydrogenase.

A

succinyl-CoA, NADH

120
Q

Name the disaccharide otherwise known as table sugar.

A

sucrose

121
Q

The position of the C-4 hydroxyl group differs in glucose and galactose. These two sugars are therefore called?

A

C-4 epimers

122
Q

In the fed state, phosphoglycerate is converted to which molecule? Which enzyme catalyzes this reaction?

A

phosphoenolpyruvate (PEP)

enolase

123
Q

Why does anaerobic glycolysis occur in the RBC despite abundant oxygen?

A

no mitochondria

124
Q

Name three uncouplers of oxidative phosphorylation.

A

2,4-DNP, thermogenin (brown adipose), high doses of salicylates (aspirin)

125
Q

How is alpha amylase deactivated?

A

by the lower pH in the stomach

126
Q

What are the two main subunits of ATP synthase and what do they do?

A

F0 is a channel for protons

F1 is where phosphorylation occurs

127
Q

What is the rate limiting step of glycogen synthesis?

A

activation of glycogen synthase by glucose (locally) and insulin (globally)

128
Q

What is another name for succinate dehydrogenase?

A

complex II of ETC

129
Q

Free glucose move across the lumen of the small intestine into the portal system by which transporter?

A

sodium-dependent hexose transporter

130
Q

Is fructose a ketose or an aldose?

A

ketose

131
Q

What is the enzyme that takes the electrons from NADPH and gives them to glutathione?

A

glutathione reductase

132
Q

Name the cells that produce salivary alpha-amylase, pancreatic alpha-amylase, alpha-glucosidase (maltase), alpha dextrinase, sucrase and lactase.

A

acinar cells

133
Q

How many monosaccharides are needed to make up a polysaccharide?

A

12 or more

134
Q

What does PEPCK require? Which hormone induces PEPCK?

A

GTP

induced by glucagon

135
Q

What is the smallest sugar polymer that is present after pancreatic enzyme digestion?

A

disaccharides

136
Q

T/F: maltose has an alpha and beta structure.

A

T

137
Q

Which ocular pathology may occur in galactokinase deficiency?

A

cataracts dt lens swelling

138
Q

In the well-fed insulin state, does acetyl-CoA enter the Krebs cycle?

A

Yes

139
Q

Where is lactase normally found?

A

intestinal brush border

140
Q

Where in the cell does the HMP pathway (aka pentose phosphate pathway) occur?

A

cytoplasm

141
Q

Which polysaccharide has an alpha-1,4 glycosidic linkage and a spiral and helical coil shape?

A

amylose

142
Q

The regulation of gluocose is primarily dependent on which two hormones?

A

insulin and glucagon

143
Q

Name the substrate and end product of aerobic glycolysis.

A

glucose and pyruvate

144
Q

What is NADPH used to make in the liver?

A

synthesis of fatty acids, cholesterol, nucleotides and glutathione

145
Q

Maltose, lactose, or sucrose: which are reducing sugars?

A

maltose and lactose

146
Q

How many ATP are produced by one NADH molecule in the ETC? How many per FADH2 molecule?

A

NADH produces 3 ATP

FADH2 produces 2 ATP

147
Q

RBC glucose is ultimately converted to which molecule?

A

lactate

148
Q

Where do the electrons go from complex III?

A

cytochrome c

149
Q

Where are the enzymes in the ETC located?

A

inner mitochondrial membrane

150
Q

Name four disaccharides that complete the conversion of starch/glycogen into usable forms of glucose.

A

maltase, sucrase, lactase, oligosaccharides

151
Q

Name two drugs that inhibit complex I of the ETC.

A

barbiturates and rotenone

152
Q

Name three positive and two negative regulators of isocitrate dehydrogenase.

A

+ isocitrate, ADP, AMP

  • ATP, NADH
153
Q

Fructose is central in which two pathways in the liver?

A

glycolysis and gluconeogenesis pathway

154
Q

Which steps of glycolysis are irreversible?

A

glucokinase/hexokinase, PFK-1, pyruvate kinase

155
Q

What do uncouplers do? What is the effect on the ETC?

A

increase permeability of the inner mitochondrial membrane to protons.

the ETC goes faster w/o establishing a proton gradient

heat is produced rather than ATP

156
Q

Which cells secrete glucagon? what other hormone inhibits the release of glucagon?

A

alpha cells of pancreas

insulin

157
Q

Which drug inhibits ATP synthase?

A

oligomycin

158
Q

What is the common name for glucose-(alpha 1,4)-glucose?

A

maltose

159
Q

Name the four monosaccharides.

A

glucose, fructose, galactose, mannose

160
Q

Is ATP produced or consumed by the pentose phosphate pathway (aka HMP shunt)?

A

neither

161
Q

How is a fructokinase deficiency differentiated form galactokinase deficiency?

A

no development of cataracts in fructokinase deficiency b/c fructose can be phosphorylated by other enzymes

162
Q

What happens to acetyl-CoA in the mitochondria if ATP is required (high ADP)?

A

if ATP is required, acetyl-CoA enters the Krebs cycle

If ATP is not needed, it will be involved fatty acids biosynthesis

163
Q

Which polysaccharide contains alpha-1,4 glycosidic linkages and is more highly branched than amylopectin with shorter (12-14) glucose residues?

A

glycogen

164
Q

What is the only type of cell that has glucose-6-P phosphatase?

A

hepatocyte

165
Q

How does glucagon effect PFK-2?

A

inhibits PFK-2, inhibiting fructose-2,6-bisP production

inhibits stimulation of PFK-1

166
Q

What are the two pathways that provide glucose in between meals?

A

conversion of pyruvate to glucose

breakdown of stored glycogen

167
Q

What are the five cofactors needed for the action of pyruvate dehydrogenase?

A

thiamine, lipoic acid, coenzyme A, FAD, NAD

168
Q

Is a six-membered ring with five carbons and one oxygen a pyranose or furanose?

A

pyranose

169
Q

What are the two amino acids that cannot create glucose through gluconeogenesis?

A

leucine and lysine

170
Q

List the four GLUT receptors from lowest to highest affinity. Where are they located?

A

Glut-2 (liver, pancreas)

Glut-4 (skeletal muscle, adipose)

Glut-1 (most tissue, brain, RBC)

Glut-3 (most tissue)

171
Q

Is insulin required for the uptake of glucose by intestinal cells?

A

no

172
Q

Which molecule is the common “crossroad” for getting energy from fats, proteins, and carbohydrates?

A

acetyl-CoA

173
Q

Cori cycle: how many ATP does it take to turn pyruvate into glucose in the liver?

A

6

174
Q

Where do the electrons go from coenzyme Q?

A

complex III

175
Q

Carbohydrates with a keto-group as the most oxidized functional group are called?

A

ketoses

176
Q

In aerobic glycolysis, pyruvate is converted to __ by the enzyme __.

A

acetyl-CoA

pyruvate dehydrogenase

177
Q

Name the four kinases in glycolysis. Which consume ATP and which produce ATP?

A

hexokinase, phosphofructokinase (consume 1 ATP per glucose)

phosphoglycerate kinase and pyruvate kinase (produce 2 ATP per glucose)

178
Q

Pyruvate can be metabolized into five compounds. Name them.

A

lactate, acetyl-CoA, oxaloacetate, phosphoenolpyruvate, alanine

179
Q

What are two enzymes involved in glycogen synthesis?

A

glycogen synthase and branching enzyme

180
Q

How does insulin effect PFK-2? How does glucagon effect PFK-2?

A

glucagon phosphorylates PFK-2 to inactivate it whereas insulin dephosphorylates PFK-2 to activate it

181
Q

Which two important products does the PPP produce?

A

ribose-5-P for nucleotide synthesis

NADPH for RBC metabolism and FA production

182
Q

In the ETC, where do the electrons go after cytochrome oxidase?

A

they are picked up by oxygen to produce H2O

183
Q

In what tissues are GLUT-1 and GLUT-3 found? What are their functions?

A

most tissues, esp. brain and RBCs

basal uptake of glucose

184
Q

Name three steps that convert glycogen to glucose.

A

glycogen -> glucose-1-P -> glucose-6-P -> glucose via glucose-6 phosphatase

185
Q

Can the acetyl CoA created between meals change to pyruvate and then to glucose?

A

acetyl CoA cannot be converted to pyruvate

186
Q

Phosphoenolpyruvate is converted to __ via __.

A

pyruvate via pyruvate kinase

187
Q

Insulin does not directly affect glucose uptake __, __, or __.

A

brain, RBCs, hepatocytes

188
Q

How does acetyl-CoA exit the mitochondria?

A

conversion to citrate (part of Krebs cycle) which goes through the citrate shuttle

189
Q

Name the two major sources of pyruvate (beginning of gluconeogenesis) between meals.

A

lactate, alanine

190
Q

Insulin dephosphorylates PFK-2 which turns glycogen synthase __ and turns phosphorylase __.

A

on

off

191
Q

With PFK-1 being the rate limiting step of glycolysis, what activates the PFK-1 and thus glycolysis?

A

indirectly activated by insulin through PFK-2

192
Q

Aldolase converts fructose 1,6 bisphosphate to __ and __.

A

glyceraldehyde-3-P and dihydoxyacetone-P (DHAP)

193
Q

Oxidation of the hydroxyl group at carbon six in glucose produces what molecule?

A

glucuronic acid

194
Q

Digestion of carbohydrates begins in the mouth. Salivary alpha amylase hydrolyzes what type of linkage?

A

alpha-1,4 glycosidic linkage

195
Q

Which two monosaccharides are epimers of glucose?

A

galactose and mannose

196
Q

What is the first step in the metabolism of fructose?

A

fructose -> fructose-1-P by fructokinase

197
Q

What are the three irreversible steps of glycolysis?

A

glucose -> glucose-6-P via glucokinase

fructose-6-P -> fructose 1,6-bis-P via PFK-1

PEP to pyruvate via pyruvate kinase

198
Q

How many ATP equivalents are generated between glucose and pyruvate?

A

6

199
Q

Does gluconeogenesis occur in the cytoplasm or in the mitochondria?

A

both

200
Q

What happens after branching enzyme makes its branches?

A

glycogen synthase extends both branches

201
Q

What is the Cori cycle? Which two cell types participate?

A

cycle of glucose to pyruvate to lactose and then back to pyruvate and then back to glucose

liver, and RBCs

202
Q

Insulin induces glucokinase. Specifically, how does induction affect rate (Vmax)?

A

increases Vmax

203
Q

What vitamin does FAD come from?

A

B2 (riboflavin)

204
Q

The HMP shunt and the malate dehydrogenase reaction both produce ___

A

NADPH

205
Q

Name the disaccharid ethat has one anomeric form.

A

sucrose

206
Q

In the ETC, where do the electrons go from NADH dehydrogenase?

A

coenzyme Q (aka ubiquinone)

207
Q

Why do RBCs only get their energy from the conversion of glycolysis, the conversion of glucose to pyruvate?

A

They lack PDH b/c they lack mitochondria

PDH, Krebs cycle and the ETC all occur in the mitochondria.

TF, RBCs lack all these stages.

208
Q

Which shuttle yields more ATP, the malate or G3P shuttle?

A

malate (3 ATP)

G3P (2 ATP)

209
Q

What enzyme converts fructose-1,6-bis-P to fructose-6-P?

A

fructose-1,6-bisphosphatase

210
Q

What effect does aspirin have on the ETC?

A

uncoupler

NPLEX - Biochemistry (8 decks)

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