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AEBI 122 > Chapter 9 - Cellular Respiration: Harvesting Chemical Energy > Flashcards

Chapter 9 - Cellular Respiration: Harvesting Chemical Energy Flashcards

1
Q

Life is what?

A

Life is work

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2
Q

Living cells require what to survive?

A

Living cells require energy from outside sources

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3
Q

Organic compounds have what?

A

organic compounds have potential energy due to arrangement of atoms

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4
Q

when compounds are broken down into simpler compounds?

A

some energy is used as work the rest dissipates as heat

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5
Q

Anabolic and Catabolic Pathways are…?

A

Anabolic and Catabolic pathways are interconnected

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6
Q

An overview of Metabolism?

A
  1. In stage 1, macromolecules are hydrolyzed into their building blocks
  2. In stage 2, building blocks are further degraded into a few common metabolites
  3. In stage 3, small molecular weight metabolites like acetyl-CoA are degraded yielding ATP
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7
Q

The breakdown of molecules is?

A

an exergonic reaction

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8
Q

what is fermentation?

A

is a partial degradation of sugar that occurs without O2

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9
Q

what is aerobic respiration?

A

consumes organic molecules and O2 and yields ATP

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10
Q

what is anaerobic respiration?

A

is similar to aerobic respiration except it consumes compounds other than O2

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11
Q

what is cellular respiration?

A

includes both aerobic and anaerobic respiration but is OFTEN used to describe AEROBIC RESPIRATION
- it is helpful to trace cellular respiration with the sugar glucose

C6H12O6 + O2 -> 6CO2 + 6H2O + Energy (ATP + Heat)

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12
Q

The cellular respiration of glucose is…?

A

is a spontaneous reaction releasing -686kcal/mol

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13
Q

what are redox reactions?

A

chemical reactions that transfer electrons between reactants are called oxidation-reduction reactions or redox reactions

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14
Q

The transfer of electrons during cellular respiration does what?

A

The transfer of electrons during chemical reactions releases energy in organic molecules
- this energy is ultimately used to synthesize ATP

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15
Q

what is oxidation?

A

a substance loses electrons or is oxidized

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16
Q

what is reduction?

A

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

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17
Q

what is a reducing agent?

A

The electron donor is called the reducing agent

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18
Q

what is the oxidizing agent?

A

the electron acceptor is called the oxidizing agent

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19
Q

what do some redox reactions do?

A

Some redox reactions do not transfer electrons but change the electron sharing inc covalent bonds

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20
Q

during cellular respiration the fuel is…?

A

during cellular respiration the fuel (glucose) is oxidized and O2 is reduced

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21
Q

Energy Harvesting via NAD+?

A
  1. electrons from organic compounds are usually first transferred to NAD+, a coenzyme
  2. electrons travel attached to protons, which in turn do not get transferred directly to oxygen, but to NAD+
  3. As an electron acceptor, NAD+ functions as an oxidizing agent during cellular respiration
  4. each NADH (reduced from NAD+)represents stored energy that is tapped to synthesize ATP
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22
Q

what is the electron transport chain (ETC)?

A

NADH passes the electron to the electron transport chain

  • the ETC passes electrons in a series of steps instead of one explosive reaction
  • The energy yielding is used to regenerate ATP
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23
Q

Cellular Respiration has 3 stages, what are they?

A
  1. Glycolysis
  2. The Citric acid Cycle (Krebs Cycle)
  3. Oxidative phosphorylation
24
Q

what is glycolysis?

A

breaks down glucose into two molecules of pyruvate

25
Q

what is the citric acid cycle?

A

completes the breakdown of glucose, pyruvate goes to CO2

26
Q

what is oxidative phosphorylation?

A

accounts for most of the ATP synthesis because it is powered by redox reactions
- accounts for almost 90% of ATP synthesis during cellular respiration

27
Q

what is substrate-level phosphorylation?

A

A smaller amount of ATP (10%) is formed in glycolysis and the citric acid cycle

28
Q

Glycolysis happens with or without?

A

oxygen, it does not make CO2

- in the presence of O2, the energy produced is further used by the citric acid cycle and oxidative phosphorylation

29
Q

Where does glycolysis occur?

A

in the cytoplasm

30
Q

What are the two phases of Glycolysis?

A
  1. Energy investment phase

2. Energy Payoff Phase

31
Q

The driving forces of glycolysis are?

A

Are these three reactions

  1. glucose
  2. G6P (glucose-6-phosphate)
  3. F6P (fructose-6-phosphate)
32
Q

What happens during the Energy investment phase of glycolysis?

A
  1. Glucose is phosphorylated by enzyme, hexokinase
  2. Isomerization of glucose into fructose by the enzyme phosphoglucoisomerase
  3. sugar broken down into 2 smaller sugars of each other by Aldolase(breaks sugars) and isomerase(converts sugars into 2 small sugars)
33
Q

What happens during the energy payoff phase of glycolysis?

A
  1. Enzyme catalyzes 2 reactions (oxidation and transfer of protons to NAD+, second phosphorylation)
  2. substrate-level phosphorylation creates 2 moles of ATP (Exergonic reaction, product is carboxylic acid)
  3. Enolase removes water to form PEP (Very high energy substrate)
  4. substrate-level phosphorylation creates ATP (Final Product Pyruvate with net gain of 2 ATP)
34
Q

what is Acetyl-CoA?

A

before the citric acid cycle can begin, pyruvate must be converted into Acetyl-CoA, which links the cycle to glycolysis

35
Q

Where does the Citric Acid Cycle occur?

A

within the mitochondrial matrix

36
Q

What does the Citric Acid Cycle do?

A

The cycle oxidizes organic fuel derived from pyruvate, generating 1ATP, 3NADH, 1FADH2 per turn

37
Q

An overview of The Citric Acid Cycle?

A
  1. The citric acid cycle has eight steps, each catalyzed by a specific enzyme
  2. The Acetyl-CoA joins the cycle by combining with oxaloacetate, forming citrate
  3. The next 7 steps decompose citrate back to oxaloacetate, making the process a cycle
  4. The NADH and FADH2 produced by the cycle relay electrons extracted from food to the electron transport chain
38
Q

what Happens after glycolysis and the citric acid cycle?

A

NADH and FADH2 account for most of the energy extracted from food
- These two electron carriers donate electrons to the electron transport chain, which powers ATP synthesis via oxidative phosphorylation

39
Q

The Electron Transport Chain?

A
  • The ETC is in the cristae of the mitochondria
  • most of the chains components are proteins, which exist in multiprotein complexes
  • Electrons drop free energy as the go down the chain and are finally passed to O2, forming H2O
  • ETC generates NO ATP
40
Q

what are cytochromes?

A

Electrons are passed through a number of proteins including cytochromes (each with an iron atom) to O2

41
Q

What is ATP synthase?

A

ETC causes proteins to pump H+ from the mitochondrial matrix into the inter-membrane space, H+ then moves back across the membrane, passing through channels in ATP synthase

42
Q

What type of flow does ATP synthase use?

A

ATP Synthase uses the EXERGONIC FLOW of H+ to drive phosphorylation of ATP

43
Q

What is Chemiosmosis?

A

the use of energy in H+ gradient to drive cellular work

- an energy coupling system, that uses energy stored in the form of of a proton gradient to drive work

44
Q

What is the proton-motive force?

A

The H+ gradient is referred to as a proton-motive force, emphasizing its capacity to do work

45
Q

During Cellular respiration most energy flows in this sequence?

A

glucose -> NADH -> ETC -> proton-motive force -> ATP

46
Q

Fermentation does what?

A

fermentation uses phosphorylation instead of ETC to generate ATP

47
Q

What is Alcohol Fermentation?

A

pyruvate is converted to ethanol in two steps, with the first releasing of CO2
- Alcohol fermentation by yeast is used in brewing, winemaking and baking

48
Q

what is Lactic Fermentation?

A

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

49
Q

What do human muscle cells do?

A

Human muscle cells use lactic acid fermentation to generate ATP when O2 is limited

50
Q

Cellular respiration and fermentation?

A

cellular respiration produces 38 ATP per glucose molecule and fermentation produces 2 ATP per glucose molecule

51
Q

what are obligate anaerobes?

A

They carry out fermentation or anaerobic respiration and CANNOT survive on the presence of O2

52
Q

what are facultative anaerobes?

A

They can survive using either fermentation or cellular respiration
- ie) yeast and many bacteria

53
Q

Metabolic Regulation?

A

Cellular activity is regulated as needed

- Regulation may involve controlling key enzymes of metabolic pathways

54
Q

How are enzymes controlled?

A
  • Enzymes are controlled by alteration in active sites
55
Q

What are the different types of alterations in active sites do enzymes undergo?

A
  1. Covalent Modification of enzymes regulated by phosphorylation such as protein kinases
  2. Allosteric Modulation by enzymes regulated by compounds binding to allosteric sites
56
Q

what is feedback inhibition (a type of Allosteric Modulation)?

A

The product of the pathway allosterically inhibits one of the first enzymes of the pathway
- most common mechanism for control

AEBI 122 (6 decks)

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