CH 9: Cellular Respiration

H+ then moves back across the membrane, passing through the protein complex called ______________.

ATP synthase

Redox reactions

Chemical reactions that transfer electrons between reactants

Pyruvate Oxidation

Conversion of pyruvate to acetyl CoA and CO2 that occurs in the mitochondrial matrix in the presence of O2.

NAD+ as an electron shuttle

Electrons from organic compounds are usually first transferred to NAD+, a coenzyme

Stages of Cellular Respiration

Glycolysis (breaks down glucose into two molecules of pyruvate) The citric acid cycle (completes the breakdown of glucose) Oxidative phosphorylation (accounts for most of the ATP synthesis)

Cellular respiration

Includes both aerobic and anaerobic respiration but is often used to refer to aerobic respiration

Glycolysis: energy investment phase

Input: glucose, 2 ATP Output: pyruvate, 2 net ATP, 2 NADH

Glycolysis: energy payoff phase

Input: glucose, 2 ATP, 2 NAD+ Output: 2 pyruvate, 2 net ATP, 2 NADH

Citric Acid Cycle inputs and outputs

Inputs: 2 pyruvate -->Acetyl-CoA; 2 oxaloacetate Outputs: 6 CO2, 2 ATP, 8 NADH, 2 FADH2

Glycolysis inputs and outputs

Inputs: glucose, 2 ATP Outputs: 2 pyvare, 2 net ATP (4 ATP), 2 NADH

In lactic acid fermentation, pyruvate is reduced by NADH, forming

NAD+ and lactate as end products, with no release of CO2

Stepwise Energy Harvest via NAD+ and the Electron Transport Chain

NADH passes the electrons to the electron transport chain

Glycolysis occurs whether or not _______ is present.

O2

______________ is the the process that generates almost 90% of the ATP

Oxidative Phosphorylation

ATP yield per molecule of glucose at each stage of cellular respiration

Review pg. 177

Free energy change during electron transport chain

See Pg. 174

H3C-CH3 --> H2C=CH2 Oxidation or Reduction?

Some redox reactions do not transfer electrons but change the electron sharing in covalent bonds. Methane is reducing agent (electron donor) and oxygen is oxidizing agent (electron acceptor)

Accounts for the smaller amount o ATP is formed in glycolysis and cytric acid cyle

Substrate-level phosphorylation

The Pathway of the Electron Transport

The electron transport chain is in the inner membrane (cristae) of the mitochondrion Most of the chain's components are proteins, which exist in multi-protein complexes (cytochromes) Electrons drop in free energy as they go down the chain and are finally passed to O2, forming H2O

Substrate-level phosphorylation

The enzyme-catalyzed formation of ATP by direct transfer of a phosphate group to ADP from an intermediate substrate in catabolism.

Oxidative Phosphorylation

The production of ATP using energy derived from the redox reactions of an electron transport chain.

H+ then move into binding sites on the rotor of ATP synthase, causing it to spin in a way that catalyzes __________________.

phosphorylation of ADP to ATP

Fermentation and anaerobic respiration enable cells to

produce ATP without the use of oxygen

The energy released as electrons are passed down the electron transport chain is used to

pump H+ from the mitochondrial matrix to the inter membrane space

a substance gains electrons is

reduced

Transfer of electrons during chemical reactions

releases energy stored in organic molecules

Fermentation uses __________________ instead of an electron transport chain to generate ATP

substrate level phosphorylation

Feedback inhibition

the most common mechanis for metabolic control

Chemiosmosis

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

Citric Acid Cycle (Krebs Cycle)

- 2 Pyruvates enter the mitochondrion - releases 2 ATP, 6NADH, and 2 FADH2 for each glucose

Proton motive force (PMF)

- potential energy stored across a membrane - cell actively pumps hydrogen ions out of the cytoplasm creating a charge across the membrane

In alcohol fermentation, pyruvate is converted to ethanol in two steps

1st: Releases CO2 from pyruvate 2nd: Produces NAD+ and ethanol Fermentation by yeast used for brewing, wine, baking

____________ and _____________ are two type of fermentation

alcohol fermention; lactic acid fermentation

Dehydrogenase

an enzyme that catalyzes the removal of hydrogen atoms from a particular molecule, particularly in the electron transport chain reactions of cell respiration in conjunction with the coenzymes NAD and FAD.

Glycolysis ("sugar splitting")

breaks down glucose into two molecules of pyruvate

Control of ____________ is based on regulating the activity of ___________ at strategic points in the catabolic pathway

catabolism; enzymes

Without oxygen, the electron transport chain will

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

During oxidative phosphorylation

chemiosmosis couples electron transport to ATP synthesis

Where does glycolysis occur?

cytoplasm

Most cellular respiration depends on

electronegative oxygen to pull electrons down the transport chain

Catabolic pathways funnel _________from many kinds of organic molecules into ___________________

electrons; cellular respiration

Two major phases of glycolysis

energy investment phase and energy payoff phase

Anaerobic respiration uses an electron transport chain with a_______________________other than oxygen, such as sulfate.

final electron acceptor

Flow of energy in cellular respiration

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

Fermentation consists of __________ plus reactions that generate ________, which can be reused by glycolysis

glycolysis; NAD+

A substance loses electrons is

oxidized

About 34% of the energy in a glucose molecule is

transferred to ATP during cellular respiration, making about 32 ATP. The rest of the energy is lost as heat.