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Biochemistry > Chapter 8- bioenergetics > Flashcards

Chapter 8- bioenergetics Flashcards

Exam 2

1
Q

What is the reactions of energy extraction and energy use called?

A

Metabolism

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2
Q

How are molecules degraded or synthesized stepwise in a series of linked reactions?

A

Through metabolic pathways

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3
Q

What is the energy currency of life?

A

ATP

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4
Q

How can ATP be formed?

A

By the oxidation of carbon fuels

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5
Q

True/False: Metabolic pathways are not regulated

A

False

They are highly regulated

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6
Q

What does metabolism do?

A

Convert one biomolecule into another required molecule

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7
Q

What do catabolic reactions do?

A

Convert energy from fuels into useful cellular energy (ATP or ion gradients)
Breaks things down

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8
Q

What do anabolic reactions do?

A

They require energy to generate complex structures from simple precursors

(polysaccharides, phospholipids, DNA)

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9
Q

What are amphibolic pathways?

A

They are metabolic pathways that can function anabolically (build up) or catabollically (break down)

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10
Q

What two criteria must be met in order to construct a metabolic pathway?

A

Individual reactions must be specific
(facilitated by enzymes to yield only a specific product)
The overall pathway must be thermodynamically favorable

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11
Q

What determines if a reaction is thermodynamically favorable or not?

A

If the free energy is negative = favorable

If the free energy is positive = not favorable

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12
Q

What is the first law of thermodynamics?

A

Energy cannot be created or destroyed

only be converted from one form to another but total energy of system remains constant

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13
Q

What is the second law of thermodynamics?

A

Entropy of any isolated system always increases

disorder must increase when transforming energy

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14
Q

What is the free energy equation?

A
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15
Q

What is the equation for standard free-energy change?

A
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16
Q

What determines the speed of the reaction?

A

Enzymes

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17
Q

What does the change in free energy indicate?

A

The direction in which a reaction will proceed

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18
Q

Do you need to add energy for a spontaneous reaction to occur?

A

no

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19
Q

What will the change of free energy be for spontaneous reactions?

A

It will be negative since it is exergonic (giving off energy)

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20
Q

How would a reaction happen if it requires energy?

A

If they are coupled to energy releasing reactions

they have a positive change of free energy and are endergonic

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21
Q

How are endergonic reactions influenced?

A

Allosteric effectors, removing product and using it as a substrate for a subsequent reaction in the pathway

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22
Q

____ ____ changes of individual enzymatic reactions are additive.

A

Free energy

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23
Q

What provides energy to do work in the cells?

A

Hydrolysis of ATP to ADP

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24
Q

______ _______ requires O2 to generate ATP.

A

Oxidative phosphorylation

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25
Q

What are the bonds between phosphate groups in ATP?

A

Phosphoanhydride bonds

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26
Q

True/False: ADP and Pi are more stable than ATP

A

True

This is why ATP has such a high energy bond

27
Q

What does hydrolysis of ATP decrease?

A 
Electrostatic repulsion
(the phosphates and oxygens all have negative charges that push away from each other so when the phosphoanhydride bond is cleaved, a lot of potential energy is released)
28
Q

Why is a free phosphate group more stable than it is in ATP?

A

Resonance (the ability of charges to move around the molecule)

29
Q

What happens to entropy when ADP is phosphorylated to ATP?

A

Entropy is decreased (there is a loss in resonance-stablized phosphate ion)

30
Q

True/False: The hydrolysis of ATP is exergonic

A

True it releases a lot of energy due to the breaking of an unstable phosphoanhydride bond

31
Q

What drives highly unfavorable reactions forward?

A

The high-energy bonds of ATP

32
Q

How is energy from ATP transfered to reactions?

A

Through phosphorylation by kinases (OH of one group attaches to the P of the phosphate)

33
Q

What does the standard free energy of ATP hydrolysis depend upon?

A

Mg2+ in order to stabilize the negative charges on the oxygens in phosphate groups

34
Q

How do unfavorable endergonic reactions proceed in metabolic pathways?

A

They are coupled with favorable exergonic reactions such as hydrolysis of ATP

35
Q

What is a high energy bond?

A

Any bond that can be hydrolyzed to release more or the same amount of energy as ATP

36
Q

What are 4 different activated intermediates used to facilitate energy transfers in biochemical reactions?

A

GTP-protein synthesis
CTP-lipid synthesis
UTP-combining sugars
ATP-transport and mechanical work

37
Q

How is ATP converted back to ADP?

A

Oxidative phosphorylation by adenylate kinase

ADP+ADP->ATP+AMP

38
Q

True/False: All high energy bonds are stable.

A

False they are all unstable

39
Q

What does generation of reduced enzymes do?

A

Provide energy for bodily processes through fuel oxidation

40
Q

What are 3 reduced enzymes used in fuel oxidation?

A

NADH
NADPH
FADH2

41
Q

What is used to generate ATP through aerobic glycolysis?

A

Carbohydrates

42
Q

What are used to generate ATP in oxidative phosphorylation?

A

NADH and FADH2

43
Q

What is fuel oxidation?

A

Means of transferring energy from chemical bonds to cellular processes

44
Q

What does cellular respiration do?

A

Transforms energy from chemical bonds of fuels into the reduction state of electron accepting coenzymes (NAD+ and FAD)

45
Q

What do reduced coenzymes do?

A

They transfer electrons to O2 in the electron transport chain
(Energy rich)

46
Q

What happens during oxidation?

A

Electrons are lost

47
Q

What happens during reduction?

A

Electrons are gained

48
Q

What is oxidation of a substance always accompanied with?

A

The reduction of another substance

49
Q

If a carbon is reduced, what happens when it is oxidized?

A

The more it is reduced the more free energy is released upon oxidation

50
Q

Why are fats a more efficient fuel source than glucose?

A

Fats are more reduced (Many CHs while glucose has many COs)

51
Q

Where do fuels donate electrons when being oxidized?

A

To the NAD+ and FAD

52
Q

What is NAD+ derived from?

A

Niacin (Vitamin B3)

53
Q

What is a coenzyme?

A

Non protein substance that takes part in an enzymatic reaction (regenerated at the end of the reaction)

54
Q

How many electrons does NAD+ accept? How many protons?

A

2 electrons and 1 proton

55
Q

What is NADH used for?

A

A source of electrons for ATP synthesis

56
Q

What is FAD derived from?

A

Riboflavin (B2)

57
Q

How many hydrogen atoms does FAD Accept?

A

2 Hydrogen atoms

58
Q

What is contained in Coenzyme A?

A

Vitamin B5 and sulfhydral group

59
Q

What kind of linkages form between carboxylic acids and sulfhydral groups?

A

Thioester linkages

60
Q

What does coenzyme A do?

A

Acts as a carrier of acetyl groups

61
Q

What is the metabolically active form of carboxylic acid?

A

Acyl-CoA

62
Q

What does having a more negative reduction potential mean?

A

The greater the tendency of the reductant member to lose electrons

63
Q

What does a more positive reduction potential mean?

A

The stronger the oxidant is more willing to accept electrons

64
Q

What are the stages of extracting energy from food?

A

Stage 1: large molecules in food are broken down into smaller units
Stage 2: small molecules are converted into acetyl-CoA
Stage 3: ATP is produced from oxidation of acetyl-CoA/ NADH and FADH2 are oxidized and transfer electrons to O2

Biochemistry (10 decks)

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