AP Biology Ch. 9 – Cellular Respiration

Catabolic pathway Fermentation Aerobic respiration Anaerobic respiration Cellular respiration Redox reaction Oxidation/reduction Reducing agent Oxidizing agent NAD+ Electron transport chain Glycolysis Citric acid cycle Oxidative phosphorylation Substrate- level phosphorylationSubstrate- level phosphorylation Pyruvate Acetyl CoA Cytochromes ATP synthase Chemiosmosis Proton-motive force Alcohol fermentation Lactic acid fermentation Obligate anaerobes Facultative anaerobes Beta oxidation

Catabolic Pathway  A metabolic pathway that releases stored energy by breaking down complex molecules  Back to contents Back to contents

Fermentation  Catabolic process that makes a limited amount of ATP from glucose without an electron transport chain and that produces a characteristic end product such as ethyl alcohol or lactic acid  Back to contents Back to contents

Aerobic Respiration  Catabolic pathway that consumes oxygen and organic molecules, producing ATP.  This is the most efficient catabolic pathway and is carried out in most eukaryotic cells and many prokaryotic organisms  Back to contents Back to contents

Anaerobic Respiration  The use of molecules other than oxygen to accept electrons at the end of the electron transport chain  Back to contents Back to contents

Cellular Respiration  The catabolic pathways of aerobic and anaerobic respiration which break down organic molecules for the production of ATP  Back to contents Back to contents

Redox Reaction  Oxidation-Reduction Reaction  A chemical reaction involving the complete or partial transfer of one or more electrons from one reactant to another  Back to contents Back to contents

Oxidation/Reduction  Oxidation – the loss of electrons from one substance in a Redox Reaction  Reduction – the addition of electrons to another substance in a Redox Reaction  Back to contents Back to contents

Reducing Agent/Oxidizing Agent  The electron donor in a Redox Reaction is the reducing agent  The electron acceptor in a Redox Reaction is the oxidizing agent  Back to contents Back to contents

NAD+  A coenzyme that is the electron carrier that receives the hydrogen atom (1 proton and 1 electron) before it continues on to oxygen in energy releasing steps  Back to contents Back to contents

Electron Transport Chain  A sequence of electron carrier molecules that shuttle electrons during the redox reactions that release energy used to make ATP  Back to contents Back to contents

Oxidative Phosphorylation  The production of ATP using energy derived from the redox reactions of an electron transport chain  The third major stage of cellular respiration  Back to contents Back to contents

Substrate-level Phosphorylation  The formation of ATP by an enzyme directly transferring a phosphate group to ADP from an intermediate substrate in catabolism  Back to contents Back to contents

Glycolysis  The splitting of glucose into pyruvate.  Occurs in almost all living cells  Serves as the starting point for fermentation and cellular respiration  Back to contents Back to contents  (back to lactic /alcohol fermentation)lacticalcohol

Pyruvate  Ionized form of pyruvic acid  During glycolysis glucose is split into two three-carbon sugars and these smaller sugars are then oxidized and rearranged to form two molecules of pyruvate  Back to contents Back to contents

The Citric Acid Cycle  Also called the Krebs Cycle  Takes place within the mitochondrial matrix of eukaryotic cells or the cytosol of prokaryotes  Second major phase of cellular respiration  Back to contents Back to contents

Acetyl CoA  Acetyl coenzyme A  Pyruvate is transformed to Acetyl CoA in the citric acid cycle  Back to contents Back to contents

Cytochromes  Iron-containing protein that is a component of electron transport chains in the mitochondria of eukaryotic cells as well as the plasma membrane of prokaryotic cells  Back to contents Back to contents

ATP Synthase  A complex of several membrane proteins that provide a port though which proteins diffuse. This complex functions in chemiosmosis with adjacent electron transport chains, using energy of a hydrogen ion (proton) concentration gradient to make ATP. Found in mitochondrial membrane in eukaryotic cells and the plasma membrane of prokaryotes  Back to contents Back to contents

Chemiosmosis  Mechanism that uses energy stored in the form of a hydrogen ion gradient across a membrane to drive cellular work such as the synthesis of ATP. Most ATP synthesis in cells occurs by chemiosmosis  Back to contents Back to contents

Proton-Motive Force  The potential energy stored in the form of an electrochemical gradient, generated by the pumping of hydrogen ions across a biological membrane during chemiosmosis  Back to contents Back to contents

Alcohol Fermentation  Glycolysis followed by followed by the conversion of pyruvate to carbon dioxide and ethyl alcohol Glycolysis  Back to contents Back to contents

Lactic Acid Fermentation  Glycolysis followed by the conversion of pyruvate to lactate, with no release of carbon dioxide Glycolysis  Back to contents Back to contents

Obligate Anaerobes  An organism that only carries out fermentation or anaerobic respiration. Such organisms cannot use oxygen and in fact may be poisoned by it  Back to contents Back to contents

Facultative Anaerobes  An organism that makes ATP by aerobic respiration if oxygen is present but that switches to anaerobic respiration or fermentation if oxygen is not present  Back to contents Back to contents

Beta Oxidation  A metabolic sequence that breaks fatty acids down to two-carbon fragments that enter the citric acid cycle as acetyl CoA  Back to contents Back to contents