Chapter 7: Cellular Respiration Flashcards by Connor Nielsen

What do organisms need to do work?

Energy

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

(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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Can energy be tranformed?

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

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Is energy transformation 100% efficient?

No because some energy is always lost as heat!

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

Some energy is lost as heat (thermal energy)

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Is ATP kinetic or potential energy?

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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What is Gibbs free energy?

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

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

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

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What is a spontaneous rxn?

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

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What is a non-spontaneous rxn?

DG>0
Requires an input of energy to happen
ENDERGONIC reaction (net input of energy)

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Is cellular respiration a spontaneous rxn?

Yes cellular respiration is a spontaneous rxn (exergonic)

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Is photosynthesis a spontaneous rxn?

No photosynthesis is a non-spontaneous rxn (endergonic)

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Are catabolic rxns exergonic or endergonic?

Exergonic

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Are anabolic rxns exergonic or endergonic?

Endergonic

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

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

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What are the types of work the body performs?

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

Does work in your body require energy?

yes work is endergonic

What is ATP?

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

What does ATP do?

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

What is the shape of ATP?

RNA with 3 phosphates attached

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

The tube would get hotter

Is ATP renewable?

yes

What is phosphorylation?

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

How is ATP coupled to cause transport work?

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.

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

How do we make ATP?

Cellular respiration

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

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  O2 (the final electron acceptor in respiration -Energy is released as e- move from high free energy to lower free energy!

What are the electron carriers?

NADH and FADH2

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

What are the steps of cellular respiration?

- Glycolysis - Pyruvate oxidation - Citric acid cycle (Krebs cycle) - Oxidative phosphorylation and chemiosmosis

Is the movement of electrons from glucose to O2 spontaneous or non-spontaneous?

- spontaneous - exergonic - coupled to endergonic rxns

Why is O2 the final e^- acceptor?

O2 is very electronegative

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)

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

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)

What is the net equation for cellular respiration?

many enzymatic reactions C6H12O6 + 6O2= 6CO2 + 6H2O + 32 ATP

Which step of cellular respiration occurs outside the mitochondria?

Glycolysis