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Cell Biology > Chapter 7: Cellular Respiration > Flashcards

Chapter 7: Cellular Respiration Flashcards

1
Q

What do organisms need to do work?

A

Energy

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2
Q

What are the types of energy and give examples of each?

A

(i) Kinetic energy: energy of motion
* Ex: solar energy, mechanical energy (movement), thermal energy
(ii) Potential energy: stored energy due to the location of structure of matter
(chemical bonds)
* Ex: chemical energy

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3
Q

Can energy be tranformed?

A

Yes, Energy can be transformed from one type to the other.

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4
Q

Is energy transformation 100% efficient?

A

No because some energy is always lost as heat!

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5
Q

When cells use ATP to power work, what happens to some of the energy?

A

Some energy is lost as heat (thermal energy)

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6
Q

Is ATP kinetic or potential energy?

A

It is potential energy as it is the chemical energy form where the chemical bonds store energy. These bonds are to be broken then they can release energy.

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7
Q

What is Gibbs free energy?

A

the portion of a system’s energy that is available for work
-see Gibbs equation

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8
Q

How does Gibbs free energy relate to a reaction’s spontaneity?

A

(-) DG = spontaneous, energy is released
(+) DG = not spontaneous, energy is consumed
D: change in Gibbs free energy

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9
Q

What is a spontaneous rxn?

A
  • DG<0
  • Proceeds alone, without added energy!
  • EXERGONIC reaction (net release of energy)
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10
Q

What is a non-spontaneous rxn?

A
  • DG>0
  • Requires an input of energy to happen
  • ENDERGONIC reaction (net input of energy)
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11
Q

Is cellular respiration a spontaneous rxn?

A

Yes cellular respiration is a spontaneous rxn (exergonic)

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12
Q

Is photosynthesis a spontaneous rxn?

A

No photosynthesis is a non-spontaneous rxn (endergonic)

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13
Q

What does glycolysis produce?

A

input: Glucose (C6H12O6)
output: 2 ATP, 2 NADH, 2 Pyruvate

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14
Q

Are anabolic rxns exergonic or endergonic?

A

Endergonic

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15
Q

Where do we get the energy to perform non-
spontaneous reactions?

A

Organisms harness the energy of spontaneous reactions to drive
non-spontaneous reactions! (Energy coupling)

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16
Q

What are the types of work the body performs?

A

(1) Chemical (Synthesis)
Ex: protein synthesis
(2) Mechanical
Ex: actin-myosin muscle contraction,
chromosome movement, beating cilia
(3) Intracellular transport
Ex: active transport

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17
Q

Does work in your body require energy?

A

yes work is endergonic

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18
Q

What is ATP?

A

Adenosine triphosphate
- The hydrolysis of ATP (ATP to ADP + Pi) is a
highly exergonic reaction
- The products (ADP + Pi) are much more
stable than the reactant (ATP)

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19
Q

What does ATP do?

A

In our cells ATP hydrolysis is coupled to
endergonic processes:
i. synthesis work
ii. transport work
iii. mechanical work

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20
Q

What is the shape of ATP?

A

RNA with 3 phosphates attached

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21
Q

What would happen if the
hydrolysis of ATP occurred in a
test tube?

A

The tube would get hotter

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22
Q

Is ATP renewable?

A

yes

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23
Q

What is phosphorylation?

A

ATP can transfer a phosphate group to a reactant to “activate it”

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24
Q

How is ATP coupled to cause transport work?

A
  • The transfer of a phosphate group onto a carrier protein causes a change in the
    conformation (shape) of the protein allowing it to move a molecule across the
    membrane.
  • De-phosphorylation returns the protein to its original shape.
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25
How is mechanical work powered by ATP?
* Motor proteins interact non-covalently with ATP. ATP hydrolysis changes the conformation of the motor protein so that it “takes a step” forward along a cytoskeletal track (different from phosphorylation!) * This conformational change is the basis for movement at the molecular, cellular and organismal level
26
How do we make ATP?
Cellular respiration
27
What type of rxn is cellular respiration?
Cellular respiration is a redox reaction * Electrons are transferred from one molecule to another * One molecule loses electrons (is oxidized) and the other gains electrons (is reduced) Oxidation: C6H12O6 = 6CO2 Reduction: 6O2 = 6H2O
28
What is an overview of cellular respiration?
* Process by which cells extract and use energy contained in organic compounds. * Organic compound (ex: glucose) is OXIDIZED! * Energy is released as e- move from organic compounds to O2 (the final electron acceptor in respiration -Energy is released as e- move from high free energy to lower free energy!
29
What are the electron carriers?
NADH and FADH2
30
What do the electron carriers do?
* Through glycolysis, pyruvate oxidation and the citric acid cycle, e- are stripped from glucose and transferred to NAD+ and FAD (are reduced to NADH and FADH2) * NADH and FADH2 “carry” and donate the electrons to the electron transport chain (ETC) to make ATP (oxidative phosphorylation) * O2 captures the electrons along with H+ to form H2O
31
What are the steps of cellular respiration?
- Glycolysis - Pyruvate oxidation - Citric acid cycle (Krebs cycle) - Oxidative phosphorylation and chemiosmosis
32
Is the movement of electrons from glucose to O2 spontaneous or non-spontaneous?
- spontaneous - exergonic - coupled to endergonic rxns
33
Why is O2 the final e^- acceptor?
O2 is very electronegative
34
What are the two ways of making ATP and which makes the most?
1) Substrate-level phosphorylation 2) Oxidative phosphorylation (most ATP is made this way)
35
What is substrate-level phosphorylation?
* enzyme catalyzes the transfer of a phosphate group to ADP from a substrate (enzyme steals phosphate from substrate and forces it join ADP) * Substrate-P + ADP = substrate + ATP * Glycolysis and Krebs cycle
36
What is oxidative phosphorylation?
* Chemiosmosis powers the production of ATP by ATP- synthase (Takes floating phosphate and joins it to ADP) * ADP + Pi = ATP * Electron transport chain (ETC)
37
What is the net equation for cellular respiration?
many enzymatic reactions C6H12O6 + 6O2= 6CO2 + 6H2O + 32 ATP
38
Which step of cellular respiration occurs outside the mitochondria?
Glycolysis
39
What does pyruvate oxidation produce?
input: 2 Pyruvate output: 2 Acetyl-CoA, 2 NADH, 2 CO2
40
What does the Krebs cycle (citric acid cycle) produce?
input: 2 Acetyl-CoA output: 6 NADH, 2 FADH2, 2 ATP, 4 CO2
41
What does the electron transport chain produce?
input: 10 NADH, 2 FADH2, 6 O2 output: 28 ATP, 12 H2O
42
What is the redox rxn that allows cellular respiration to happen?
Oxidation: C6H12O6 = 6CO2 Reduction: 6O2 = 6H2O
43
Where do electrons move?
From high free energy to lower free energy
44
What are the electron carriers?
- Through glycolysis, pyruvate oxidation and the citric acid cycle, e- are stripped from glucose and transferred to NAD+ and FAD (are reduced to NADH and FADH2) - NADH and FADH2 “carry” and donate the electrons to the electron transport chain (ETC) to make ATP (oxidative phosphorylation) - O2 captures the electrons along with H+ to form H2O
45
What is the final electron acceptor?
O2 because it is very electronegative
46
Is the movement of e- from glucose to O2 spontaneous or non-spontaneous?
Spontaneous (DG<0)
47
What are the two ways ATP is made?
1. Substrate-level phosphorylation 2. Oxidative phosphorylation
48
What is Substrate-level phosphorylation?
- enzyme catalyzes the transfer of a phosphate group to ADP from a substrate - Glycolysis and Krebs cycle - Steals phosphate from substrate and forces it join ADP
49
What is Oxidative phosphorylation?
- Chemiosmosis powers the production of ATP by ATP- synthase - Takes floating phosphate and joins it to ADP - electron transport chain (ETC)
50
What are the two phases of glycolysis?
1. energy investment: Glucose+2ATP=2 glyceraldehyde 3 phosphate (G3P) *catalyzed by Phosphofructokinase 2. energy payoff: 2G3P=2pyruvate+4ATP+2NADH
51
What is Phosphofructokinase?
- Phosphofructokinase is an enzyme important to glycolysis, important for negative feedback inhibition - Most enzymes can catalyze a reaction in both directions however Phosphofructokinase catalyzes in one direction making it a key regulator of cellular respiration
52
What is pyruvate oxidation?
- Pyruvate is transported into the mitochondrial matrix and oxidized to acetyl-CoA - Pyruvate = CO2 + NADH + Acetyl-CoA (happens twice, once for each pyruvate) - 2 pyruvate per glucose
53
What is the Krebs cycle?
- The final oxidation steps take place and the remaining high energy electrons from glucose are transferred to NAD+ and FAD (NAD+ and FAD are reduced) - What is left of glucose (2 Acetyl-CoA) is fully oxidized to produce: * 6 NADH * 2 FADH2 * 2 ATP * 4 CO2
54
Where does the Krebs cycle occur?
The mitochondrial matrix
55
What does the ETC contain?
* 4 enzyme complexes (I,II, III and IV; contain cofactors that act as e- carriers) * 2 mobile e- carriers (coenzyme Q and cytochrome C) * Complex II (shuttles e- from FADH2 to coenzyme Q)
56
Where is the ETC?
Embedded in the inner mitochondrial membrane
57
How does the ETC work?
* e- move through the ETC from high energy to low energy (spontaneous) * Energy released is used to pump protons (non- spontaneous) into the intermembrane space
58
What does Complex 1 do?
* Receives e- from NADH * Pumps protons from matrix into intermembrane space
59
What does Coenzyme Q (ubiquinone) do?
* Receives e- from Complex I or FADH2 (via complex II) * Moves in the lipid bilayer (lipid soluble)
60
What does Complex 3 do?
* Receives e- from coenzyme Q * Pumps protons from matrix into intermembrane space * Contains cytochromes (contain an iron-containing heme group)
61
What does Cytochrome C do?
* Receives e- from Complex III
62
What does complex 4(cytochrome oxidase) do?
* Receives e- from cytochrome C * Transfers e- to O2 to produce H2O * Pumps protons from matrix into intermembrane space * Contains cytochromes
63
Why is the movement of electrons along the ETC spontaneous/exergonic?
because e- are moving from low to high electronegativity (“downhill”)
64
Does FADH2 or NADH have a lower free energy?
FADH2 has lower free energy than NADH and enters the ETC at a lower energy via Complex II!
65
What is chemiosis?
The movement of protons (H+) across a selectively permeable via ATP synthase membrane by passive transport (exergonic)
66
What is the energy coupling for oxidative phosphorylation?
Chemiosmosis (exergonic) is coupled to the production of ATP by ATP synthase (endergonic)
67
Where is the concentration of H^+ greater the intermembrane space or the matrix?
- The intermembrane space thus is why the H^+ flows into the matrix producing energy like hydro - This powers ATP synthesis (ADP + Pi = ATP)
68
What is ATP synthase?
- Enzyme embedded in the inner mitochondrial membrane that synthesizes ATP from ADP and Pi - Powered by the proton gradient created by ETC (movement of H^+)
69
Is chemosis spontaneous?
Yes, Spontaneous process (high [H+] to low [H+])
70
What type of ATP production is chemiosis and how much ATP is made?
Oxidative phosphorylation and 28 ATP

Cell Biology (9 decks)

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