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Biochemistry > Chapter 27 > Flashcards

Chapter 27 Flashcards

1
Q

The food we eat serves two main purposes

A

It fulfills our energy needs

provides the raw materials to build the compounds
our bodies need

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2
Q

Before either of these processes can take place, food—
carbohydrates, fats, and proteins—must be

A

broken down into small molecules that can be absorbed through the intestinal walls

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2
Q

Complex carbohydrates Examples

A

Di and Polysaccharides

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3
Q

Complex carbohydrates in the diet are broken
down by

A

enzymes and stomach acid to produce monosaccharides

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3
Q

Also comes from the enzymatic breakdown of glycogen that is stored in the liver and muscles until needed

A

Glucose

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4
Q

Once monosaccharides are produced, they can be used either to

A

build new oligo- and polysaccharides

Or Provide energy

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5
Q

The specific pathway by which energy is extracted from monosaccharides is called

A

Glycolysis

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6
Q

Ingested fats are hydrolyzed by _______ to ______ which are absorbed through the _________

A

Lipases

Glycerol

Intestine

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7
Q

The specific pathway used by the cells to obtain energy from fatty acids is
called

A

b-oxidation

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8
Q

Proteins are hydrolyzed by

A

HCl in the stomach

Digestive enzymes (Pepsin)

Intestines ((trypsin, chymotrypsin, and carboxypeptidases)

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9
Q

The nitrogen of the amino acids is catabolized through

A

oxidative deamination

urea cycle

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10
Q

The carbon skeletons of the amino acids enter the common catabolic pathway as either

A

a-ketoacids (pyruvic, oxaloacetic, and a-ketoglutaric acids)

acetyl coenzyme A

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11
Q

The first steps of glucose metabolism

A

energy is consumed rather than released At the expense of 2 molecules of ATP later converted into ADP

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11
Q

Efficiency is achieved because

A

A minimal number of chemical
steps are required

Energy-producing factories of the body are localized in the mitochondria

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12
Q

Third step of glycolysis

A

a second phosphate group is bonded to yield fructose 1,6-bisphosphate

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13
Q

glucose is ….

A

Phosphorylated

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14
Q

First step of glycolysis

A

glucose 6-phosphate is formed

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15
Q

second step of glycolysis

A

after isomerization to fructose 6-phosphate

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16
Q

The first 3 steps in glycolysis is called the _______ Process

A

Activation

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17
Q

The biochemical pathway
that breaks down glucose to
pyruvate

A

Glycolysis

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18
Q

Step 4 in glycolysis

A

The C6 compound, fructose 1,6-bisphosphate, is broken into two C3 fragments

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19
Q

Step 5 in glycolysis

A

glyceraldehyde 3-phosphate is oxidized to 1,3-bisphosphoglycerate

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19
Q

The two C3 fragments in equilibrium

A

glyceraldehyde 3-phosphate

dihydroxyacetone phosphate

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20
Q

Step 6 in glycolysis

A

The phosphate from the carboxyl group is
transferred to ADP, yielding ATP and 3-phosphoglycerate

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21
Q

The hydrogen of the aldehyde group is removed by
the ___ _________

A

NAD+ coenzyme

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22
Q

Step 7 in glycolysis

A

Isomerization

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23
Q

Step 8 in glycolysis

A

Dehydration

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24
Q

Step 9 in glycolysis

A

phosphoenolpyruvate loses its remaining phosphate and yields pyruvate and another ATP molecule

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25
Q

the “payoff” step

A

Step 9

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26
Q

Two ATP molecules produced (one for each C3 fragment) represent

A

the net yield of ATPs in glycolysis

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27
Q

Step 9 is catalyzed by an enzyme…

A

pyruvate kinase

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28
Q

This enzyme plays a key role in the regulation of glycolysis

A

pyruvate kinase

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29
Q

when plenty of ATP is available, glycolysis is…

A

Shut down

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30
Q

All of these glycolysis reactions occur in the________ outside the _________ Because they occur in the absence of __,

A

Cytoplasm

Mitochondria

O2

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30
Q

when ATP is scarce and AMP levels are high, the glycolytic pathway is…

A

Speeded up

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31
Q

The end product of glycolysis is_______

A

Pyruvate

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32
Q

Step 10 of glycolysis certain bacteria and yeast, pyruvate undergoes _____________ to produce _______

A

Decarboxylation

Ethanol

33
Q

glucose 6-phosphate can be shunted
to the…. in step 19

A

Pentose phosphate pathway

33
Q

The acetyl CoA then enters the _____ _____ _____ in Step 13

A

Citric acid cycle

34
Q

Pyruvate goes through an ________ __________ in the presence of _________ _in Step 12 to produce _________

A

oxidative decarboxylation

coenzyme A

acetyl CoA

35
Q

Pentose phosphate pathway can produce _____ and _______ in step 20

A

NADPH

Ribose

36
Q

______ is needed in many biosynthetic processes, including synthesis of unsaturated fatty acids cholesterol, and amino acids as well as photosynthesis

A

NADPH

37
Q

When is glucose 6-phosphate is used in the pentose phosphate pathway

A

when the body needs these synthetic ingredients more than energy

37
Q

needed for the synthesis of RNA

A

Ribose

38
Q

ribose 5-phosphate can be channeled back to glycolysis through

A

glyceraldehyde 3-phosphate

39
Q

NADPH is badly needed in red blood cells as a defense against

A

oxidative damages

40
Q

main agent used to keep hemoglobin in its reduced form

A

Glutathione

41
Q

an insufficient supply of NADPH leads to

A

Destruction of Red blood cells causing severe anemia

42
Q

Most energy production takes place in ______ _______ cells

A

Skeletal muscle

43
Q

__ ATP molecules are produced for each NADH+, H+ produced in the cytoplasm, as is the case in the mitochondria

A

3

44
Q

When we construct the energy balance sheet, we use___ ____ molecules for each NADH+, H+ produced in the cytoplasm

A

2 ATP

45
Q

The biochemical pathway for the breakdown of
glycogen to glucose

A

Glycogenolysis

46
Q

the main storage form of the chemical energy of lipids

A

triglycerides

47
Q

The first step in glycerol utilization is an activation step. The body uses one ATP molecule to form….

A

glycerol 1-phosphate

48
Q

The biochemical pathway that degrades fatty acids to
acetyl CoA by removing two carbons at a time and yielding energy

A

b-oxidation

49
Q

The glycerol phosphate is oxidized by NAD+ to

A

dihydroxyacetone phosphate

50
Q

proposed that the body utilizes fatty acids as an energy source by breaking them down into fragments

A

Franz Knoop

1904

51
Q

In the general case of lipid catabolism, this activation occurs in the _____

A

Cytosol

52
Q

The fatty acid oxidation occurs inside the ___________, so the acyl group of acyl CoA must pass through the __________ membrane.

A

mitochondrion

mitochondrial

53
Q

In the first oxidation, two hydrogens are removed, creating a _______ ______ ____between the alpha and beta
carbons of the acyl chain

A

Trans double bond

53
Q

the acyl group transporter

A

Carnitine

54
Q

Step 1 of B oxidation

A

convert ATP to AMP and inorganic phosphate

55
Q

Step 2 of B oxidation

A

dehydrogenation

56
Q

Step 3 of B oxidation

A

the double bond is hydrated. An enzyme specifically places the hydroxyl group on C-3, the beta carbon

57
Q

A secondary alcohol is oxidized to a ______ at the beta carbon

A

Ketone

58
Q

Step 4 of B oxidation

A

The second oxidation; dehydrogenation

The two hydrogens and electrons
removed are transferred to the NAD+

59
Q

Step 5 of B oxidation

A

the enzyme thiolase cleaves the terminal C2 fragment from the chain

60
Q

a typical and quite abundant fatty acid

the C18 saturated fatty acid.

A

stearic acid

60
Q

After the B oxidation cycle is over, The cycle then starts again with __________, which is now two
carbon atoms shorter

A

the remaining acyl CoA

61
Q

Produced from malate, but it is also produced by the carboxylation of phosphoenolpyruvate (PEP)

Essential for the continuous operation of the citric acid cycle

A

Oxaloacetate

62
Q

The liver is able to condense two acetyl CoA molecules to produce

A

acetoacetyl CoA

63
Q

When the acetoacetyl CoA is hydrolyzed, it yields __________, which can be reduced to form b-hydroxybutyrate

A

acetoacetate

64
Q

These two compounds, together with smaller amounts of acetone, are collectively called

A collective name
for acetone, acetoacetate, and
b-hydroxybutyrate; compounds
produced from acetyl CoA in the
liver that are used as a fuel for
energy production by muscle cells
and neurons

A

ketone bodies

65
Q

The proteins of our foods are_________ to amino acids in __________

A

Hydrolyzed

Digestion

66
Q

Unlike carbohydrates and fats, however, they cannot be stored, so excess amino acids are ….

A

Catabolized for energy production

67
Q

Nitrogen catabolism in the liver occurs in three stages:

A

Transamination

Oxidative deamination

The urea cycle

68
Q

The exchange of the amino group of an amino acid and a
keto group of an a-ketoacid

A

Transamination

69
Q

In the first stage, transamination, amino acids transfer their amino groups to….

A

a-ketoglutarate

70
Q

The second stage of nitrogen catabolism is the _________ -_________ of glutamate, which occurs in the mitochondrion

A

Oxidative deamination

71
Q

The reaction in which the amino group
of an amino acid is removed and an a-ketoacid is formed

A

Oxidative deamination

72
Q

A cyclic pathway that produces urea from ammonia and
carbon dioxide

A

Urea cycle

73
Q

In the third stage, the NH4+ is converted to urea through the ____ _____

A

Urea Cycle

74
Q

Step 1 of the urea cycle

A

NH4+ is condensed with CO2 in the mitochondrion
to form an unstable compound, carbamoyl phosphate

75
Q

Step 2 of the urea cycle

A

Carbamoyl phosphate is condensed with ornithine

76
Q

Step 3 of the urea cycle

A

A second condensation reaction in the cytoplasm takes place between citrulline and aspartate, forming argininosuccinate

77
Q

Step 4 of the urea cycle

A

the argininosuccinate is split into arginine and fumarate

78
Q

Step 5 of the urea cycle

A

arginine is hydrolyzed to urea and ornithine

79
Q

The ornithine reenters the _________, completing
the cycle

A

mitochondrion

80
Q

After transamination of amino acids to glutamate, the alpha amino group is removed from glutamate by….

A

oxidative deamination

81
Q

Those amino acids that yield a carbon
skeleton that is degraded to pyruvate or another intermediate capable of conversion to glucose (such as oxaloacetate) are called ….

A

glucogenic

82
Q

example of a ketogenic amino acid

A

ketogenic

83
Q

amino acids are both glucogenic and ketogenic—for
example…

A

phenylalanine

Biochemistry (5 decks)

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