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Biology 202 > Chapter 9 > Flashcards

Chapter 9 Flashcards

1
Q

What generates O2 and organic molecules used for cellular respiration?

A

photosynthesis

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2
Q

What do exergonic catabolic reactions produce?

A

energy

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3
Q

What is included in cellular respiration?

A

both aerobic and anaerobic respiration
-often used to refer to aerobic respiration

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4
Q

Aerobic respiration is similar in broad principle to

A

the combustion of gasoline in an automobile engine after oxygen is mixed with hydrocarbon fuel

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5
Q

What is fermentation?

A

a partial degradation of sugars that occur without O2

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6
Q

Aerobic respiration consumes what?

A

organic molecules and O2

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7
Q

What does aerobic respiration yield?

A

ATP

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8
Q

What makes anaerobic respiration different from aerobic respiration?

A

consumes compounds other than O2

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9
Q

Redox reactions

A

chemical reactions that transfer electrons between reactants = oxidation-reduction reactions

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10
Q

What happens in oxidation?

A

a substance loses electrons “oxidized”

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11
Q

What happens in reduction?

A

a substance gains electrons “reduced”(the amount of positive charge is reduced)

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12
Q

Reducing agent

A

the electron donor

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13
Q

oxidizing agent

A

the electron receptor

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14
Q

During cellular respiration, what is oxidized and what is reduced?

A

the fuel(such as glucose) is oxidized and O2 is reduced

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15
Q

The more hydrogen atoms one molecule has the

A

better energy source it is

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16
Q

What is NAD+?

A

Nicotinamide adenine dinucleotide, a coenzyme derivative of the vitamin niacin

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17
Q

Where are electrons from organic compounds usually first transferred to?

A

NAD+

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18
Q

NAD+ functions as an

A

oxidizing agent during cellular respiration

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19
Q

NADH

A

the reduced from of NAD+ represents stored energy that is tapped to synthesize ATP

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20
Q

Electron transport chain

A

-passes electrons in a series of steps instead of one explosive reaction
-NADH passes the electrons into the chain
-O2 pulls electrons down the chain in an energy-yielding tumble

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21
Q

What occurs to the energy yielded from the electron transport chain?

A

it is used to regenerate ATP

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22
Q

What are the 3 stages of harvesting of energy from glucose?

A

-glycolysis(breaks down glucose into 2 molecules of pyruvate)
-citric acid cycle(completes the breakdown of glucose)
-oxidative phosphorylation(accounts for most of the ATP synthesis)

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23
Q

What is the process that generates most of ATP?

A

oxidative phosphorylation(powered by redox reactions)

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24
Q

What accounts for almost 90% of ATP generated by cellular respiration?

A

oxidative phosphorylation

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25
What is formed in glycolysis and citric acid cycle by substrate level phosphorylation?
a smaller amount of ATP
26
For each molecule of glucose catabolized to CO2 & water by respiration, the cell makes up how many molecules of ATP?
32 molecules
27
Glycolysis
-"splitting of sugar" breaks down glucose into 2 molecules of pyruvate -occurs whether or not O2 is present -occurs in cytoplasm & has 2 major phases
28
What are the 2 major phases of glycolysis?
-energy investment(the cell spends ATP) -energy payoff(investment is repaid with interest)
29
Citric acid cycle
-pyruvate enters the mitochondrion (in eukaryotic cells) where the oxidation of glucose is completed -in the presence of O2 -"krebs cycle or tricarboxylic acid cycle" -completes break down of pyruvate to CO2 -the cycle oxidizes organic fuel derived from pyruvate, generating: 1 ATP, 3 NADH, & 1 FADH2 per turn
30
what must occur before the citric acid cycle can begin?
pyruvate must be converted to acetyl Coenzyme A(Acetyl CoA, CoA derives from a B5 vitamin), which links glycolysis to citric acid cycle
31
How many steps does the citric acid cycle have?
8 steps, each catalyzed by a specific enzyme
32
First step of citric acid cycle
the acetyl group of acetyl CoA joins the cycle by combining with oxaloacetate, forming citrate
33
The next 7 steps of the citric acid cycle
break down citrate back to oxaloacetate
34
NADH & FADH2
account for most of the energy extracted from food
35
What do NADH & FADH2 do?
donate electrons to electron transport chain, which powers ATP synthesis via oxidative phosphorylation
36
Where is the electron transport chain located?
in the inner membrane (cristae) of the mitochondrion
37
Electron Transport
-carriers alternate reduced and oxidized states as they accept and donate electrons -electrons drop in free energy as they go down the chain and are finally passed to O2, forming H2O -electrons are transferred from NADH or FADH2 to the electron transport chain - electrons are passed through a number of proteins including cytochromes(each with an iron atom) to O2 -transport chain generates no ATP directly -breaks the large free-energy drop from food to O2 into smaller steps that release energy in manageable amounts
38
What causes proteins to pump H+ from the mitochondrial matrix to inter membrane space?
electron transfer in electron transport chain
39
What does the H+ do?
moves back across membrane, passing through proton pump, ATP synthase
40
What does ATP synthase use?
exergonic flow of H+ to drive phosphorylation of ATP
41
What's an example of chemiosmosis?
the use of energy in a H+ gradient to drive cellular work
42
What does the energy stored in H+ gradient across membrane do?
couples the redox reactions of electron transport chain to ATP synthesis
43
Energy flow
glucose-NADH-electron transport chain-proton motive force-ATP
44
Glycolysis (not definition)
-anaerobic(does not need oxygen) -occurs in cytoplasm glucose-2 pyruvate+ 2NADH + 2ATP
45
Krebs cycle
-aerobic(needs oxygen) -occurs in matrix of mitochondria 2 Acetyl-coenzymeA - 4CO2 + 6NADH+ 2ATP + 2FADH2
46
Electron Transport System
-aerobic(needs oxygen) -occurs in inner membrane of mitochondria/cristae-invaginations passage of electrons from NADH to O2- H2O +H+gradient 26-28 ATP
47
DG for 1 mol Glucose
-686 kcal/mo
48
DG stored in 1 molecule of ATP
-7.3 kcal/mol
49
7.3 kcal/mol(32)
233.6 kcal/mol
50
233.6x100/686
34%( potential energy stored in glucose converted to ATP)
51
Even the best man made engines can only achieve
25% efficiency
52
Anaerobic respiration
uses electron transport chain with a final electron acceptor other than O2(sulfate)
53
Fermentation
uses substrate-level phosphorylation instead of an electron transport chain to generate ATP -consists of glycolysis plus reaction that regenerate NAD+ which can be reused by glycolysis
54
What are the 2 common types of fermentation?
alcohol fermentation lactic acid fermentation
55
Alcohol fermentation
pyruvate converted to ethanol, releasing CO2
56
Lactic acid fermentation
pyruvate forming lactate, no release of CO2-human muscle cells to make ATP when O2 is scarce
57
What occurs in all 3: fermentation, anaerobic, and aerobic respiration?
-all use glycolysis to oxidize glucose & harvest chemical energy of food -NAD+ is the oxidizing agent that accepts electrons during glycolysis
58
What is different in all 3?
final electron acceptors: -fermentation: an organic molecule(pyruvate, acetaldehyde) -cellular respiration: O2
59
True or False: cellular respiration produces 2 ATP per glucose and fermentation produces 32 ATP per glucose
False
60
Obligate Anaerobes
-carry out fermentation or anaerobic respiration -cannot survive in presence of O2 -I.e. brain neurons, can carry out only aerobic oxidation of pyruvate, not fermentation
61
Facultative anaerobes
-can survive using either fermentation or cellular respiration -pyruvate is a fork in the metabolic road that leads to 2 alternative catabolic routes -i.e. human muscle cells can behave as facultative anaerobes
62
Glycolysis accepts a wide range of
carbohydrates
63
Proteins
must be digested to amino acids; amino groups can feed glycolysis or the citric acid cycle, the -NH2 is release as urea
64
Fats
digested to glycerol( used in glycolysis) & fatty acids(used in generating acetyl CoA) -fatty acids are broken down by beta oxidization & yield as much ATP as an oxidized gram of carbohydrate
65
Glucose can be synthesized from
pyruvate
66
Fatty acids can be synthesized from
acetyl CoA and dihydroxyacetone phosphate
67
What do anabolic and biosynthetic pathways do with ATP?
consume not generate
68
Feedback inhibition
most common mechanism for control -if ATP concentration drops, respiration speeds up; if plenty of ATP, respiration slows down

Biology 202 (5 decks)

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