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2C PRELIMS > BIOCHEM Citric Acid Cycle, Saccharides, Glycolysis > Flashcards

BIOCHEM Citric Acid Cycle, Saccharides, Glycolysis Flashcards

1
Q

is the final common pathway for the oxidation of carbohydrate, lipid, and protein because glucose,
fatty acids, and most amino acids are metabolized to acetyl CoA or intermediates of the cycle.

A

Citric Acid Cycle

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2
Q

Krebs Cycle has a central role in ____________, ____________, and ______________________

A

Gluconeogenesis, Lipogenesis, Interconversion of amino acids.

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3
Q

The cycle starts with reaction between the acetyl moiety of
____________ and the four-carbon dicarboxylic acid __________, forming a six-carbon tricarboxylic acid,__________ . In the subsequent reactions, two molecules of _______ are released and oxaloacetate is regenerated

A

acetyl-CoA, oxaloacetate, citrate, CO2

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4
Q

________________ provides the main pathway for ATP
formation linked to the oxidation of metabolic fuels

A

The citric acid cycle

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5
Q

The citric acid cycle process is ________, requiring __________ as the final oxidant of the reduced coenzymes

A

aerobic, oxygen

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6
Q

The enzymes of the citric acid cycle are located in the __________________, either free or attached to the inner ______________ membrane

A

mitochondrial matrix, mitochondrial

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7
Q

Entry of Carbon

A

Anaplerosis

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8
Q

Exit of Carbon

A

Cataplerosis

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9
Q

The initial reaction between acetyl-CoA and oxaloacetate
(C4) to form citrate (C6) is catalyzed by

A

citrate synthase

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10
Q

Citrate is isomerized to isocitrate by the enzyme

A

aconitase

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11
Q

________ ATP ARE FORMED PER TURN OF THE CITRIC ACID CYCLE

A

TEN

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12
Q

Four of the B vitamins are essential in the citric acid cycle and hence energy-yielding metabolism:

A

riboflavin, niacin, thiamin (vitamin B1), pantothenic acid

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13
Q

_________, as FAD, is the cofactor for succinate dehydrogenase;

A

riboflavin

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14
Q

_________, as NAD+ , is the electron acceptor for isocitrate dehydrogenase, α-ketoglutarate dehydrogenase, and malate dehydrogenase;

A

niacin

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15
Q

________, as thiamin diphosphate, is the coenzyme for decarboxylation in the α- ketoglutarate dehydrogenase reaction; and

A

thiamin (vitamin B1)

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16
Q

__________, as part of coenzyme A, is esterified to carboxylic acids to form acetyl CoA and succinyl-CoA.

A

pantothenic acid

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17
Q

All the intermediates of the Krebs cycle are potentially ___________, since they can give rise to oxaloacetate, and hence production of glucose

A

glucogenic

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18
Q

The key enzyme that catalyzes transfer out of the cycle into gluconeogenesis is _________________________, which catalyzes the decarboxylation of oxaloacetate to phosphoenolpyruvate, with GTP acting as
the phosphate donor

A

phosphoenolpyruvate carboxykinase

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19
Q

___________________ reactions form pyruvate from alanine, oxaloacetate from aspartate, and α-ketoglutarate from glutamate

A

aminotransferase

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20
Q

Acetyl-CoA, formed from pyruvate by the action of pyruvate dehydrogenase, is the major substrate for ________________________________ synthesis in nonruminants

A

long-chain fatty acid

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21
Q

In most tissues, where the primary role of the citric acid cycle is in energy-yielding metabolism, _________________via the respiratory chain and oxidative phosphorylation regulates citric acid cycle activity

A

respiratory control

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22
Q

The citric acid cycle is _____________, since in addition to
oxidation it is important in the provision of ____________________ for gluconeogenesis, ______________ for fatty acid synthesis, and interconversion of amino acids. For these processes to be sustained they rely on a balance of anaplerosis and cataplerosis in the citric acid cycle

A

amphibolic, carbon skeletons, acetyl-CoA

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23
Q

Producers of NADH+ in Krebs Cycle

A

Conversion of Isocitrate to Alpha-Ketoglutarate
Conversion of Alpha-Ketoglutarate to Succinyl-CoA
Conversion of Malate to Oxaloacetate

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24
Q

Producers of FADH in Krebs Cycle

A

Conversion of Succinate to Fumarate

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25
Q

are extremely polar molecules that are widely
distributed in plants and animass.

A

Carbohydrates

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26
Q

is the most important carbohyrate; most ietary carbohyrate is absorbe into
the boostream as simpe sugars

A

Glucose

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27
Q

is a major metaboic fue of mammas (except ruminants)an a universa fue of the fetus

A

Glucose

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28
Q

Glucose is the precursor for synthesis of a the other carbohyrates in the boy, incuing ______________ for storage, _______ and _________ in nucleic acids, _______________ for synthesis of _____________ in mik, in glycolipids, and in combination with protein in gycoproteins

A

glycogen, ribose & deoxyribose, galactose, lactose

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29
Q

is the stuy of the roes of saccharies in heath an disease

A

Glycobiology

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30
Q

is the entire compement ofsaccharies of an organism, whether free or in more compexmoecues.

A

Glycome

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31
Q

an analogous term to genomics and proteomics, is the comprehensive study of
glycomes, including genetic, physiological, pathological, and other aspects

A

Glycomics

32
Q

Classification of Saccharides

A

(1) monosaccharides
(2) disaccharides
(3) oligosaccharides
(4) polysaccharides.

33
Q

Also called as simple sugars and are sugars that cannot
be further hydrolyzed to simpler saccharides.

A

MONOSACCHARIDES

34
Q

They can be classified as trioses, tetroses, pentoses,
hexoses, or heptoses which depend on the number of
carbon atoms and location of the carbonyl (C=O)

A

MONOSACCHARIDES

35
Q

formed when the aldehyde or
ketone has been reduced to alcohol group, and are also
synthesized by reduction of monosaccharides for use in
the manufacture of foods for weight reduction and for
diabetics.

A

Polyhydric Alcohol

36
Q

They are the condensed products of two (2) monosaccharide units
(ex. lactose, maltose, and sucrose).

A

DISACCHARIDES

37
Q

They are the condensed products of 3-10 monosaccharides and mostly are not digested by human enzymes.

A

OLIGOSACCHARIDES

38
Q

They are the condensed products of more than 10
monosaccharide units (ex. starches and dextrans which
can be linear or branched polymers)

A

POLYSACCHARIDES

39
Q

They’re sometimes classified as hexosans or pentosans
depending on the constituent monosaccharides
(hexoses, pentoses, respectively).

A

POLYSACCHARIDES

40
Q

A wide variety of polysaccharides collectively known as
____________________________ are not digested by human
enzymes and are major component of dietary fiber (ex.
cellulose and inulin)

A

nonstarch polysaccharides

41
Q
  • account for some of the
    properties of glucose
  • shows the linear
    arrangement of the carbon
    atoms and the aldehyde
    group
A

Straight Chain
Structural Formula
(Aldohexose)

42
Q
  • glucose can undergo a
    reaction between the
    aldehyde group and a
    hydroxyl group
  • thermodynamically
    favored and accounts for
    other properties of glucose
A

Cyclic Structure (Hemiacetal
Formation)

43
Q
  • a way to present the cyclic
    structure of glucose in a two dimensional format
  • the molecule is viewed from
    the side and above the plane
    of the ring
  • the bonds nearest to the
    viewer are bold and thickened,
    while the hydroxyl groups are
    shown above or below the
    plane of the ring
A

Haworth Projection

44
Q

OH group on the right side when drawn in
the fischer projection

A

D-isomer

45
Q

OH group on the left side when drawn in
the fischer projection

A

L-isomer

46
Q

When polarized light passes through a solution of an
optical isomer, it rotates the light.
If the light rotates to the right, the compound is

A

dextrorotatory +

47
Q

When polarized light passes through a solution of an
optical isomer, If the light rotates to the left, the compound is

A

levorotatory -

48
Q

six-membered ring

A

Pyranose

49
Q

five-membered ring

A

Furanose

50
Q

Over 99% of glucose in solution is in the _______________ form

A

pyranose

51
Q

are special types of sugars that are very
similar in structure but differ in the position of just
one hydroxyl (-OH) group.

A

Epimers

52
Q

are different forms of a sugar molecule that
arise when the sugar forms a ring structure.

A

Anomers

53
Q

The carbon atom that was part of the carbonyl group (aldehyde or ketone) becomes the
anomeric carbon in the ring

A

Anomeric Carbon

54
Q

The hydroxyl group on the anomeric
carbon is on the opposite side of the ring from the
CH2OH group.

A

Alpha (α) form

55
Q

The hydroxyl group on the anomeric
carbon is on the same side of the ring as the CH2OH
group.

A

Beta (β) form

56
Q
  • Metabolic intermediates
  • Important in glycolysis and pentose phosphate pathway.
A

Trioses, Tetroses, and Pentoses:

57
Q
  • Integral in nucleotides, nucleic acids, and
    several coenzymes.
  • Example: Ribose in RNA and deoxyribose
    in DNA.
A

Pentoses

58
Q

Sugars where one hydroxyl
group (-OH) is replaced by a
halogen atom (H)

A

DEOXY SUGARS

59
Q

a homopolymer of glucose forming an α-glucosidic chain, called a glucosan or glucan

A

Starch

60
Q

most important dietary carbohydrate in cereals,
potatoes, legumes, and other vegetables.

A

Starch

61
Q

is a measure
used to determine how much a
food can affect your blood
sugar levels

A

Glycemic Index

62
Q
  • a main source of energy that is
    stored primarily in your liver
    and muscles.
  • sometimes called animal starch.
A

Glycogen

63
Q
  • Regulates the amount of
    glucose in the blood.
  • It is used clinically to assess
    kidney function.
A

Insulin

64
Q

is the chief constituent of plant cell walls which is insoluble and forms long, straight chains strengthened by cross-linking hydrogen
bonds.

A

Cellulose

65
Q

is a structural
polysaccharide in the exoskeleton
of crustaceans and insects, also in
mushrooms.

A

Chitin

66
Q

occurs in fruits and is a
polymer of galacturonic acid linked α1 → 4, with some galactose an/or arabinose branches, and is partially
methylated.

A

Pectins

67
Q

are proteins containing branched or unbranched oligosaccharide chains, including fucose.

A

Glycoproteins

68
Q

is the main
pathway through which cells metabolize glucose and other
carbohydrates.

A

Glycolysis

69
Q

While glycolysis can occur under anaerobic conditions, this has a price. It ____________________ formed per mole of glucose oxidized, so that much more glucose must be metabolized under anaerobic than aerobic conditions to supply the same quantity of ATP to supply cellular work

A

limits the amount of ATP

70
Q

glucose enters glycolysis by phosphorylation to glucose-6-phosphate, catalyzed by _______________

A

hexokinase

71
Q

Isomerization of glucose-6-phosphate to fructose-6-phosphate catalyzed by _________________________

A

glucosephosphate isomerase

72
Q

Fructose-6-phosphate is then phosphorylated again to generate fructose-1,6-bisphosphate catalyzed by ____________________________

A

phosphofructokinase

73
Q

Fructose-1,6-bisphosphate is cleaved into two 3-carbon fragments. This reaction is catalyzed by __________________

A

aldolase

74
Q

Dihydroxyacetone phosphate (DHAP) is converted to glyceraldehyde-3-phosphate catalyzed by _____________

A

triosephosphate isomerase

75
Q

_____________- An intermediate product of glycolysis, which can either enter the mitochondria for ________________ (if oxygen is available) or be converted to ________________ (if oxygen is scarce)

A

Pyruvate, oxidation, lactate

76
Q

reactions in glycolysis that are markedly exergonic and are considered to be physiologically irreversible

A

reactions catalyzed by:
- hexokinase(and glucokinase),
- phosphofructokinase, and
- pyruvate kinase,

2C PRELIMS (16 decks)

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