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Biochemistry (material for exam II) > Metabolism > Flashcards

Metabolism Flashcards

1
Q

What is metabolism

A

A linked series of chemical reactions that begins with a particular molecule and converts it into some other molecule in a carefully defined fashion

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2
Q

The pathways of metabolism are _______, and their activity is coordinated by sensitive means of communication in which _______ are predominant

A

interdependent, allosteric enzymes

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3
Q

Reactions that convert energy form fuels into biologically useful forms

A

Catabolic

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4
Q

Reactions that require inputs of energy to proceed

A

Anabolic

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5
Q

Reactions that form complex molecules

A

Anabolic

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6
Q

what is the universal currency of free energy in biological systems

A

ATP

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7
Q

The release of more phosphate groups allows for a

A

greater free energy release

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8
Q

What are three compounds that have a higher phosphoryl-transfer potential than ATP (to ADP) (list them in order form highest lowest)

A

Phosphoenolpyruvate (PEP) (-61.9), Creatine phosphate (-49.4) , 1.3- Biphosphoglycerate (1,3-BPG) (-43.1)

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9
Q

What is the free energy when ATP is hydrolyzed to ADP

A

-30.5 kJ mol^-1

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10
Q

What is the free energy when ATP is hydrolyzed to AMP

A

-45.6 kJ mol^-1

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11
Q

ATP consists of

A

adenine, a ribose, and a triphosphate unit

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12
Q

The active form of ATP is usually a complex of ATP with

A

Mg^2+ or Mn^2+

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13
Q

Groups with higher phosphoryl-transfer potential can

A

transfer phosphates to groups with a lower potential

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14
Q

Why is it important that ATP has a phosphoryl-transfer potential that is intermediate among the biologically important phosphorylated molecules

A

This intermediate position enables ATP to function efficiently as a carrier of phosphoryl groups

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15
Q

The amount of ATP in the muscle suffices to sustain contractile activity for

A

less than a second

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16
Q

what serves as a reservoir of high-potential phosphoryl groups that can be readily transferred to ADP

A

Creatine phosphate

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17
Q

The reaction of creatine phosphate + ADP —-> ATP + creatine is catalyzed by

A

creatine phosphate

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18
Q

What is the principal immediate donor of free energy

A

ATP

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19
Q

ATP is consumed within a _____ of its formation

A

minute

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20
Q

The _____ of carbon fuels is an important source of cellular engery

A

oxidation

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21
Q

The total quantity of ATP in the body is limited to approximately

A

100 grams

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22
Q

The turnover of the small quantity of ATP is

A

very high

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23
Q

A resting human being consumes about ____ of ATP in 24 hours

A

40kg

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24
Q

During strenuous exertion, the rate of utilization of ATP may be as high as

A

0.5 kg/minute

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25
Q

Motion, Active transport, signal amplification, and biosynthesis can take place only if

A

ATP is continually regenerated from ADP

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26
Q

Generation of ____ is one of the primary roles of catabolism

A

ATP

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27
Q

carbon in fuel molecules— such as glucose and fats—- is oxidized to _____. The resulting electrons are captured and used to regenerate ATP from ___ and __-

A

CO2, ADP, phosphate

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28
Q

In aerobic organisms, the ultimate electron acceptor in oxidation of carbon is _____-

A

Oxygen

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29
Q

What is the oxidation product of carbon fuels in aerobic organisms

A

Carbon Dioxide

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30
Q

in terms of oxidation- The more reduced a carbon is to begin with, the

A

more free energy is released by its oxidation

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31
Q

Which would release more free energy methane or methanol

A

methane

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32
Q

When a fuel is oxidized the oxidation takes place ____ carbon at a time

A

one

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33
Q

For a 2 hour run about how much ATP is utilized

A

about 60kg (132 pounds)

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34
Q

Which is more likely to be stored saturated or polyunsaturate fatty acids

A

Saturated

35
Q

The carbon-oxidation energy is used in some cases to create a ______________ and in other cases to creat an ______. In either case, the end point is the formation of ____

A

Compound with high phosphoryl-transfer potential, ion gradient. ATP

36
Q

what are some reasons that phosphates came to play a prominent role in biology

A

phosphate esters are thermodynamically unstable while being kinetically stable. thus energy release cn be manipulated by enzymes.
Their kinetic stability makes them ideal regulatory molecules, added to proteins by kinases and removed only by phosphatases

37
Q

What is the stability of phosphate esters due to

A

the negative charges that make them resistant to hydrolysis in the absence of enzymes

38
Q

What account for the presence of phosphates in the backbone of DNA

A

Their negative charge makes them resistant to hydrolysis in the absence of enzymes

39
Q

What do phosphatases do

A

they remove phosphates from proteins

40
Q

What do kinases do

A

They add phosphates to proteins

41
Q

The binding of phosphates to metabolites can have what effect in terms of the cell membrane

A

it causes them to no longer diffuse through the membrane

42
Q

what are the three stages of extracting energy from foodstuffs

A

digestion (no energy captured)- protein are hydrolyzed to their 20 different amino acids, polysaccharides are hydrolyzed to simple sugars such as glucose, and lipids are hydrolyzed to glycerol and fatty acids.
stage 2- numerous small molecules are degraded to a few simple units that play a central role in metabolism. most are converted to acetyl unit of acetyl CoA. (some ATP generation)
Stage 3- ATP is produced form the complete oxidation of the acetyl unit of acetyl CoA. ( krebs/TAC cycle/citric acid cycle

43
Q

For each acetyl group that is oxidized in the citric acid cycle how many pairs of electrons are transferred

A

4 pairs (three to NAD+ and one to FAD)

44
Q

in aerobic organisms what is used to transfer electrons to oxygen and why

A

electrons are not directly transferred to oxygen and special electron carriers must be used, which are either pyridine nucleotides or flavins. The reduced forms of these carriers then transfer their high-potential electrons to oxygen

45
Q

What is the reactive part of NAD+

A

its nicotinamide ring, a pyridine derivative synthesized form the vitamin niacin.

46
Q

NAD+ accepts

A

a hydrogen ion and two electrons, which is the equivalent to a hydride ion

47
Q

In NAD+ has a positive charge at the

A

Nitrogen

48
Q

NAD+ is the ___ form

A

oxidized form

49
Q

many activated carriers function as

A

coenzymes

50
Q

FAD is the ___ form

A

oxidized form

51
Q

The reactive pare of FAD is its

A

isoalloxazine ring, a derivative of the vitamin riboflavin

52
Q

FAD accepts

A

two electrons and two protons

53
Q

How is FMN (flavin monnucleotide) different form FAD

A

it lacks adenine

54
Q

High-potential electrons are required in most biosyntheses because

A

the precursors are more oxidized than the products. So, reducing power is needed in addition to ATP

55
Q

What is the electron donor in most reductive biosyntheses

A

NADPH

56
Q

NADPH is the ____ form of NADP+

A

reduced form

57
Q

NADPH differs from NADH in that the

A

2’- hydroxyl group of its adenosine moiety is esterified with phosphate.

58
Q

NADH is primarily used for the generation of

A

ATP

59
Q

The extra phosphoryl group on NADPH is a tag that enables enzymes

A

to distinguish between high-potential electrons to be used in anabolism and those to be used in catabolism

60
Q

Coenzyme A is derived from

A

Vitamin pantothenate

61
Q

Acyl groups are important in both

A

anabolism and catabolism

62
Q

Acyl groups function in the oxidation of

A

fatty acids

63
Q

Acyl groups function in anabolism

A

synthesis of membrane lipids

64
Q

What is the reactive site of CoA

A

Terminal sulfhydryl group

65
Q

Acyl groups are linked to CoA by

A

thioester bonds

66
Q

what is the free energy for the hydrolysis of acetyl CoA

A

-31.4 kJ mol^-1

67
Q

Why is a thioster bond more thermodynamically unsable than an oxygen ester

A

because the electrons of the C=O bond cannot form resonance structures with the C-S bond that are stable as those they can form with the C-O bond.

68
Q

Acetyl CoA carries an ____ acyl group

A

Activated

69
Q

The kinetic stability of activated carriers in the absence of specific catalysts is essential for their biological function because

A

it enables enzymes to control the flow of free energy and reducing power

70
Q

most interchanges of activated groups in metabolism are accomplished by a rather

A

small set of carriers

71
Q

almost all the activated carriers that act as coenzymes are derived from

A

vitamins

72
Q

Vitamins are

A

organic molecules that are needed in small amounts in the diets of some higher animals

73
Q

Is it biologically more efficient to ingest vitamins than to synthesize the enzymes required to construct them form simple molecules

A

Yes

74
Q

Vitamin A (retinol) is a precursor of

A

retinal, the light-sensitive group in rhodopsin and other visual pigments, and retinoic acid, an important signaling molecules.

75
Q

Function of Vitamin A

A

roles in vision, growth, and reproduction

76
Q

Function of Vitamin C (Ascorbic acid)

A

Antioxidant

77
Q

Functions of Vitamin D

A

Regulation of calcium and phosphate metabolism

78
Q

Functions of Vitamin E

A

Antioxidant

79
Q

Functions of Vitamin K

A

Blood Coagulation

80
Q

Metabolism is regulated through what 3 ways

A
  1. ) the amounts of enzymes
  2. ) their catalytic activities
  3. ) The accessibility of substrates
81
Q

How are enzymes controlled for

A

The rate of transcription for genes coding them.

they depend on the rate of synthesis and rate of degradation

82
Q

How do we control catalytic activity

A

Allosteric control
- feedback inhibition
hormones coordinate metabolic relations

83
Q

How do we control the accessibility of substrates

A

Compartmentalization segregates opposed reactions

Biochemistry (material for exam II) (10 decks)

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