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Biology 1406 > Chapter 9 (Notes) > Flashcards

Chapter 9 (Notes) Flashcards

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1
Q

Living cells require energy from

A

outside sources.

Some animals, such as the chimpanzee, obtain energy be eating plants, and some animals feed on other organisms that eat plants.

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2
Q

Energy flows into an ecosystem as

A

sunlight and leaves as heat.

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3
Q

Photosynthesis generates O2 and organic molecules, which

A

are used in cellular respiration.

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4
Q

Cells use chemical energy stored in organic molecules to

A

regenerate ATP, which powers work.

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5
Q

Several processes are central to

A

cellular respiration and related pathways.

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6
Q

The breakdown of organic molecules is

A

exergonic.

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7
Q

Three ways cells make ATP

A

Fermentation
Aerobic respiration
Anaerobic respiration

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8
Q

Fermentation is a

A

partial degradation of sugars that occurs without O2

((do this as last resort???))

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9
Q

Aerobic respiration

A

consumes organic molecules and O2 and yields ATP

tons of ATP) (need a lot of oxygen

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10
Q

Anaerobic respiration

A

is similar to aerobic respiration but consumes compounds other than O2.

(doesn’t need O2 but makes tons of ATP?)

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11
Q

Cellular respiration includes both

A

aerobic and anaerobic respiration but is often used to refer to aerobic respiration.

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12
Q

Although carbohydrates, fats, and proteins are all consumed as fuel, it is helpful to

A

trace cellular respiration with the sugar glucose.

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13
Q

Chemical equation for Cellular Respiration

A

C6H12O6 + 6 O2 —> 6 CO2 + 6 H2O + Energy (ATP + heat)

1 glucose + 6 Oxygen –> 6 molecules of Carbon Dioxide + 6 Water molecules + Energy in the two forms of ATP and Heat.

((2 things in and three things out))

(((glucose is oxidized. Oxygen is reduced(gains electrons))))

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14
Q

The transfer of electrons during chemical reactions releases

A

energy stored in organic molecules.

This released energy is ultimately used to synthesize ATP.

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15
Q

Chemical reactions that transfer electrons between reactants are called

A

oxidation-reduction reactions, or redox reactions.

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16
Q

In oxidation,

A

a substance loses electrons, or is oxidized.

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17
Q

In reduction,

A

a substance gains electrons, or is reduced (the amount of positive charge is reduced)

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18
Q

LEO GER

LEO (the lion) (says) GER

A

Oxidation:
L- Loses
E- Electrons
O- Oxidized

Reduction:
G-Gains
E- Electrons
R- Reduced

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19
Q

The electron donor is called the

A

reducing agent.

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20
Q

The electron receptor is called the

A

oxidizing agent.

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21
Q

Some redox reactions do not transfer electrons but

A

change the electron sharing in covalent bonds.

An example is the reaction between methane and O2.
-One way to follow electron movements is to watch the hydrogens.

  • **Look for hydrogens.
  • **Things that have hydrogens have a lot of electrons.
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22
Q

During cellular respiration, the fuel (such as glucose) is

A

oxidized, and O2 is reduced.

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23
Q

Cellular respiration allows us to break off

A

energy into small amounts.

(???)

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24
Q

Organic molecules that have lots of H (hydrogen) are good fuels because

A

they have e- (electrons) that can be transferred to oxygen.

This must happen stepwise.
Glucose burning releases 686 kcal/mol glucose.

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25
Q

In cellular respiration, glucose and other organic molecules ae

A

broken down in a series of steps.

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26
Q

Electrons from organic compounds are usually first transferred to

A

NAD+, a coenzyme.

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27
Q

As an electron acceptor, NAD+ functions as an

A

oxidizing agent during cellular respiration.

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28
Q

Each NADH (the reduced form of NAD+) represents

A

stored energy that is tapped to synthesize ATP.

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29
Q

NADH passes the electrons to the

A

electron transport chain.

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30
Q

Unlike an uncontrolled reaction, the electron transport chain passes electrons in a

A

series of steps instead of one explosive reaction.

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31
Q

O2 (oxygen) pulls electrons down the electron transport chain in an

A

energy-yielding tumble.

The energy yielded is used to regenerate ATP.

Food&raquo_space; NADH&raquo_space; Electron Transport Chain&raquo_space; Oxygen (((» water)))

Most electrons follow this “downhill route” ^^

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32
Q

Harvesting of energy from glucose has three stages

A
  1. Glycolysis
  2. The Citric Acid Cycle
  3. Oxidative Phosphorylation
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33
Q

Glycolysis

A

-breaks down glucose into two molecules of pyruvate.

  • Location it occurs: Cytoplasm
  • How ATP is made: Substrate-Level Phosphorylation (SLP)
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34
Q

The Citric Acid Cycle

Pyruvate Oxidation

A

completes the breakdown of glucose.

  • Location it occurs: Matrix Mitochondria
  • How ATP is made: Substrate-Level Phosphorylation (SLP)
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35
Q

Oxidative Phosphorylation

A

accounts for most of the ATP synthesis.

  • Location it occurs: Inner Membrane of Mitochondria
  • How ATP is made: Oxidative Phosphorylation (OP)
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36
Q

The process that generates most of the ATP is called

A

oxidative phosphorylation because it is powered by redox reactions.

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37
Q

Oxidative phosphorylation accounts for almost 90% of the

A

ATP generated by cellular respiration.

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38
Q

A smaller amount of ATP is formed in glycolysis and the citric acid cycle by

A

substrate-level phosphorylation.

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39
Q

For each molecule degraded to CO2 and water by respiration, the cell makes up to

A

32 molecules of ATP.

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40
Q

Glycolysis (“splitting of sugar”) breaks down glucose into

A

two molecules of pyruvate.

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41
Q

Glycolysis occurs in the cytoplasm and has two major phases

A
  • energy investment phase

- energy payoff phase

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42
Q

Glycolysis occurs whether or not

A

O2 is present.

43
Q

Glycolysis harvests chemical energy by

A

oxidizing glucose to pyruvate.

44
Q

After pyruvate is oxidized, the citric acid cycle completes the

A

energy-yielding oxidation of organic molecules.

45
Q

In the presence of O2, pyruvate enters the mitochondrion (in eukaryotic cells) where the

A

oxidation of glucose is completed.

46
Q

Before the citric acid cycle can being, pyruvate must be converted to

A

acetyl Coenzyme A (acetyl CoA), which links glycolysis to the citric acid cycle.

This step is carried out by a multienzyme complex that catalyses three reactions.

47
Q

The citric acid cycle, also called the Krebs cycle, completes the

A

breakdown of pyruvate to CO2.

48
Q

The citric acid cycle oxidizes organic fuel derived from

A

pyruvate, generating 1 ATP, 3 NADH, and 1 FADH2 per turn.

-2 turns per 1 original glucose molecule.

49
Q

The acetyl group of acetyl CoA joins the citric acid cycle by

A

combining with oxaloacetate, forming citrate.

50
Q

The next seven steps in the citric acid cycle decompose the citrate back to

A

oxaloacetate, making the process a cycle.

51
Q

The NADH and FADH2 produced by the citric acid cycle relay electrons extracted from

A

the food to the electron transport chain.

52
Q

During oxidative phosphorylation,

A

chemiosmosis couples electron transport to ATP synthesis.

53
Q

Following glycolysis and the citric acid cycle, NADH and FADH2 account for

A

most of the energy extracted from food.

54
Q

These two electron carriers (NADH and FADH2) donate electrons to the electron transport chain, which

A

powers ATP synthesis via oxidative phosphorylation.

55
Q

The electron transport chain is in the

A

inner membrane (cristae) of the mitochondrion.

56
Q

Most of the chain’s (electron transport chain) components are proteins, which

A

exist in multiprotein complexes.

57
Q

The carriers (NADH and FADH2??) alternate reduced and oxidized states as they

A

accept and donate electrons.

58
Q

Electrons drop in free energy as they go

A

down the chain and are finally passed to O2, forming H2O.

59
Q

The first proteins have lower affinity for electrons (less electronegative)

A

the final electron acceptor O2 is very electronegative.

60
Q

Electrons are transferred from NADH or FADH2 to the

A

electron transport chain.

61
Q

Electrons are passed through a number of proteins including

A

cytochromes (each with an iron atom) to O2.

62
Q

The electron transport chain generates

A

no ATP directly.

63
Q

The electron transport chain breaks the large free-energy drop from food to O2 into

A

smaller steps that release energy in manageable amounts.

64
Q

Chemiosmosis

A

the energy-coupling mechanism

65
Q

Electron transfer in the electron transport chain causes proteins to

A

pump H+ from the mitochondrial matrix to the intermembrane space.

H+ then moves back across the membrane, passing through the proton, ATP synthase.

66
Q

ATP synthase uses the

A

exergonic glow of H+ to drive phosphorylation of ATP.

67
Q

This is an example of chemiosmosis, the use of

A

energy in a H+ gradient to drive cellular work.

68
Q

The energy stored in a H+ gradient across a membrane couples the

A

redox reactions of the electron transport chain to ATP synthesis.

69
Q

The H+ gradient is referred to as a

A

proton-motive force, emphasizing its capacity to do work.

70
Q

During cellular respiration, most energy flows in this sequence

A

glucose –> NADH –> electron transport chain –> proton-motive force –> ATP

71
Q

About 34% of the energy in a glucose molecule is transferred to

A

ATP during cellular respiration, making about 32 ATP.

Several reasons why the number of ATP is not known exactly.

72
Q

Fermentation and Anaerobic respiration enable cells to

A

produce ATP without the use of oxygen.

73
Q

Most cellular respiration require

A

O2 to produce ATP.

74
Q

Without O2 as a final electron acceptor,

A

the electron transport chain will cease to operate.

In that case, glycolysis couples with fermentation or anaerobic respiration to produce ATP.

75
Q

Anaerobic respiration uses an

A

electron transport chain with a final electron acceptor other than O2, for example sulfate.

76
Q

Fermentation uses substrate-level phosphorylation instead of an

A

electron transport chain to generate ATP.

77
Q

Fermentation consists of

A

glycolysis plus reactions that generate NAD+, which can be reused by glycolysis.

78
Q

Two common types of Fermentation are

A

alcohol fermentation
and
lactic acid fermentation.

79
Q

In alcohol fermentation, pyruvate is converted to

A

ethanol in two steps, with the first releasing CO2.

80
Q

Alcohol fermentation by yeast is used in

A

brewing, winemaking, and baking.

2 Ethanol, 2 CO2, 2 ATP and 2NAD+ are the products generated from 1 glucose.

81
Q

In lactic acid fermentation, pyruvate is

A

reduced to NADH, forming lactate as an end product, with no release of CO2.

82
Q

Lactic acid fermentation by some fungi and bacteria is used to

A

make cheese and yogurt.

83
Q

Human muscle cells use lactic acid fermentation to

A

generate ATP when O2 is scarce.

1 glucose makes 2ATP, 2 lactate, and 2 NAD+

84
Q

Fermentation, Anaerobic respiration, and Aerobic respiration all use glycolysis (net ATP=2) to oxidize

A

glucose and harvest chemical energy of food.

85
Q

In fermentation, Anaerobic respiration, and Aerobic respiration, NAD+ is

A

the oxidizing agent that accepts electrons during glycolysis.

86
Q

The processes have different final electron acceptors:

A

an organic molecule (such as pyruvate or acetaldehyde) in fermentation and O2 in cellular respiration.

87
Q

Cellular respiration produces 32 ATP per glucose molecule; and

A

fermentation produces 2 ATP per glucose molecule.

88
Q

Obligate anaerobes carry out

A

fermentation or anaerobic respiration and cannot survive in the presence of O2.

89
Q

Yeast and many bacteria are facultative anaerobes, meaning that

A

they can survive using either fermentation or cellular respiration.

90
Q

In a facultative anaerobe, pyruvate is the

A

fork in the metabolic road that leads to two alternative catabolic routes.

91
Q

Ancient prokaryotes are thought to have used glycolysis long before there was oxygen in the atmosphere.

A

Very little O2 was available in the atmosphere until about 2.7 billion years ago, so early prokaryotes likely used only glycolysis to generate ATP.

92
Q

Glycolysis is a very

A

ancient process.

93
Q

Glycolysis and the Citric Acid Cycle connect to

A

many other metabolic pathways.

94
Q

Glycolysis and the citric acid cycle are major intersections to

A

various catabolic and anabolic pathways.

95
Q

Catabolic pathways funnel electrons from many kinds of organic molecules into

A

cellular respiration.

96
Q

Glycolysis accepts a

A

wide range of carbohydrates.

97
Q

Proteins must be digested to amino acids; amino groups can feed

A

glycolysis or the citric acid cycle.

98
Q

Fats are digested to

A

glycerol (used in glycolysis) and fatty acids (used in generating acetyl CoA)

99
Q

Fatty acids are broken down by

A

beta oxidation and yield acetyl CoA.

100
Q

An oxidized gram of fat produces more than

A

twice as much ATP as an oxidized gram of carbohydrate.

101
Q

The body uses small molecules to

A

build other substances.
We don’t just eat to get ATP – portions of our diet go to building up molecules.

These small molecules may come directly from food, from glycolysis, or from the citric acid cycle.

102
Q

Feedback Inhibition is the

A

most common mechanism for control.

The end product inhibits an enzyme used in the synthesis pathway.

103
Q

If ATP concentration begins to drop, respiration speeds up;

A

when there is plenty of ATP, respiration slows down.

104
Q

Control of catabolism is based mainly on

A

regulating the activity of enzymes at strategic points in the catabolic pathway.

Biology 1406 (53 decks)

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