D.N.AD.N.AObjective: Sequence the events of cell respiration, including major reactants and Objective: Sequence the events of cell respiration, including major reactants and

products of glycolysis, krebs cycle, ETC, and fermentation. products of glycolysis, krebs cycle, ETC, and fermentation.

1. ATP serves as a common energy source for organisms because1. ATP serves as a common energy source for organisms because

A. it is the smallest energy moleculeA. it is the smallest energy molecule

B. it stores the least energy of any energy sourceB. it stores the least energy of any energy source

C. its energy can be easily transferred to do cellular workC. its energy can be easily transferred to do cellular work

D. it is extremely stable and can be stored in the cell for long periods of timeD. it is extremely stable and can be stored in the cell for long periods of time

E. traces of it have been found in fossils of ancient organisms dating back to E. traces of it have been found in fossils of ancient organisms dating back to the beginning of life on Earththe beginning of life on Earth

2. Which metabolic process is common to both aerobic cellular respiration and 2. Which metabolic process is common to both aerobic cellular respiration and alcoholic fermentation?alcoholic fermentation?

A.A. Krebs cycleKrebs cycle

B.B. GlycolysisGlycolysis

C.C. Electron transport chainElectron transport chain

D.D. Conversion of pyruvic acid to acetyl CoAConversion of pyruvic acid to acetyl CoA

E.E. Production of a proton gradientProduction of a proton gradient

D.N.AD.N.AObjective: Sequence the events of cell respiration, including Objective: Sequence the events of cell respiration, including

major reactants and products of glycolysis, krebs cycle, ETC, and major reactants and products of glycolysis, krebs cycle, ETC, and fermentation. fermentation.

Which of the following describes glycolysis?Which of the following describes glycolysis?

A. It begins the oxidation of glucoseA. It begins the oxidation of glucose

B. It produces a small amount of ATPB. It produces a small amount of ATP

C. Generates NADHC. Generates NADH

D.D. Splits glucose to form two molecules of pyruvateSplits glucose to form two molecules of pyruvate

E.E. All of the aboveAll of the above

What is the function of OWhat is the function of O22 in aerobic metabolism in aerobic metabolism

A. Oxidizes glucose, making it more soluble in waterA. Oxidizes glucose, making it more soluble in water

B. Reduces enzymes, limiting glucose synthesisB. Reduces enzymes, limiting glucose synthesis

C. Activates enzymes in the citric acid (Krebs) CycleC. Activates enzymes in the citric acid (Krebs) Cycle

D. Accepts electrons through the electron transport chainD. Accepts electrons through the electron transport chain

E. Transforms ion gates to allow diffusion of K+E. Transforms ion gates to allow diffusion of K+

During complete aerobic cellular respiration, each molecule of During complete aerobic cellular respiration, each molecule of glucose broken down in the mitochondria can yield 36 glucose broken down in the mitochondria can yield 36 molecules of ATP. What conditions might lead to a decrease in molecules of ATP. What conditions might lead to a decrease in the amount of ATP produced in a given system?the amount of ATP produced in a given system?

A. An increase in the amount of glucose added to the systemA. An increase in the amount of glucose added to the system

B. A decrease in the amount of light the system is exposed toB. A decrease in the amount of light the system is exposed to

C. A decrease in the amount of oxygen available in the C. A decrease in the amount of oxygen available in the systemsystem

D. A decrease in the amount of carbon dioxide available in the D. A decrease in the amount of carbon dioxide available in the systemsystem

E. An increase in the amount of ADP in the systemE. An increase in the amount of ADP in the system

Cellular Respiration OverviewCellular Respiration Overview

Cellular RespirationCellular Respiration

Aerobic Cellular Respiration occurs in the Aerobic Cellular Respiration occurs in the presence of oxygen in the cytosol and the presence of oxygen in the cytosol and the mitochondriamitochondriaThe process can be summarized as:The process can be summarized as:

CC66HH1212OO66 + 6O + 6O22 6CO 6CO22 + 6H + 6H22O + Energy O + Energy (ATP and Heat) (ATP and Heat)

Redox ReactionRedox Reaction

Redox ReactionsRedox Reactions – Reactions involving – Reactions involving the transfer of electronsthe transfer of electronsOxidationOxidation – When a substance loses – When a substance loses electrons in a redox reactionelectrons in a redox reaction– The substance accepting the electron is The substance accepting the electron is

known as the oxidizing agentknown as the oxidizing agent

ReductionReduction – When a substance gains – When a substance gains electrons in a redox reactionelectrons in a redox reaction– The substance donating the electron is known The substance donating the electron is known

as the reducing agentas the reducing agent

Example: Sodium ChlorideExample: Sodium Chloride

Becomes Oxidized (loses electron)

Becomes Reduced (gains electron)

Oxidizing

Agent

Reducing

Agent

Production of ATPProduction of ATP

Becomes Oxidized

Becomes Reduced

Reducing

Agent

Oxidizing

Agent

Overview of the ProcessOverview of the Process

With oxygen present, there are 3 main With oxygen present, there are 3 main steps in cellular respiration:steps in cellular respiration:

1.1. GlycolysisGlycolysis

2.2. The Citric Acid Cycle (Krebs Cycle)The Citric Acid Cycle (Krebs Cycle)

3.3. Oxidative Phosphorylation: ETC and Oxidative Phosphorylation: ETC and chemiosmosischemiosmosis

GlucoseGlycolysis Pyruvate

Oxidative Phosphorylation:

ETC And

Chemiosmosis

NADH and FADH2

NADH

ATP ATP ATP

Types of PhosphorylationTypes of Phosphorylation

Phosphorylation is how ATPs are formedPhosphorylation is how ATPs are formed

Oxidative PhosphorylationOxidative Phosphorylation – Phosphates – Phosphates added to ADP via the redox reactions in the added to ADP via the redox reactions in the ETCETC

Substrate Level PhosphorylationSubstrate Level Phosphorylation – An – An enzyme transfers a phosphate from a enzyme transfers a phosphate from a substrate, to ADP (glycolysis and citric acid substrate, to ADP (glycolysis and citric acid cycle)cycle)

GlycolysisGlycolysis

Glyco=Sugar; Lysis= SplitGlyco=Sugar; Lysis= Split

In Glycolysis, Glucose is split into two 3-carbon In Glycolysis, Glucose is split into two 3-carbon pyruvate (pyruvic acid) moleculespyruvate (pyruvic acid) molecules

In order to begin, glycolysis requires the input In order to begin, glycolysis requires the input of energy (ATP)of energy (ATP)

Glycolysis occurs in the cytosolGlycolysis occurs in the cytosol

Lets look at Glycolysis in a very simple form:Lets look at Glycolysis in a very simple form:

Net Gain in GlycolysisNet Gain in Glycolysis

2 ATP2 ATP- 2 ATP (Energy investment phase)- 2 ATP (Energy investment phase)

+ 4 ATP+ 4 ATP (Energy yielding phase) (Energy yielding phase)

+ 2 ATP+ 2 ATP

2 NADH2 NADH– Electron carriersElectron carriers– Will be used to make ATP later Will be used to make ATP later

2 Pyruvate2 Pyruvate

C C C C C C

C C C

C C C

C C C

C C C

Glucose

Pyruvic Acid

2ATP

2 ADP

4 ADP

4ATP

2 NAD+

2 NADH

Citric Acid CycleCitric Acid Cycle

Also referred to as the Krebs CycleAlso referred to as the Krebs Cycle

Takes place in the mitochondrial matrixTakes place in the mitochondrial matrix

When oxygen is present, the Citric Acid When oxygen is present, the Citric Acid Cycle follows GlycolysisCycle follows Glycolysis

This cycle takes pyruvate from glycolysis This cycle takes pyruvate from glycolysis to make ATP, NADH, and FADHto make ATP, NADH, and FADH22

Citric Acid Cycle SimplifiedCitric Acid Cycle Simplified

Pyruvate turns into acetyl CoAPyruvate turns into acetyl CoA

Acetyl CoA enters the Citric Acid Cycle Acetyl CoA enters the Citric Acid Cycle and is then transformed into citrate and is then transformed into citrate

Citric Acid Cycle - ProductsCitric Acid Cycle - Products

3 NADH, 1 FADH2, 1ATP, and CO3 NADH, 1 FADH2, 1ATP, and CO22 are are

produced in the Citric Acid Cycleproduced in the Citric Acid Cycle– Each NADH will generate about 3 ATPEach NADH will generate about 3 ATP– FADH2 will generate about 2 ATPFADH2 will generate about 2 ATP

The COThe CO22 released from this cycle is the same released from this cycle is the same

COCO22 that you exhale while breathing that you exhale while breathing

Electron Transport ChainElectron Transport Chain

The ETC converts the NADH and FADHThe ETC converts the NADH and FADH22

from glycolysis and the Krebs Cycle into ATPfrom glycolysis and the Krebs Cycle into ATP

Occurs in inner membrane of mitochondrionOccurs in inner membrane of mitochondrion

The energy in each NADH molecule moves The energy in each NADH molecule moves enough protons (Henough protons (H++) into the mitochondrial ) into the mitochondrial matrix to create ATP (oxidative matrix to create ATP (oxidative phosphorylation)phosphorylation)

Oxidative PhosphorylationOxidative Phosphorylation

This is the process of extracting ATP form This is the process of extracting ATP form the energy in NADH and FADHthe energy in NADH and FADH22

Occurs in the cristae of the mitochondriaOccurs in the cristae of the mitochondria

The electrons are passed through an ETC The electrons are passed through an ETC to release ATPto release ATP

The final electron acceptor is oxygenThe final electron acceptor is oxygen

Oxygen bonds with 2 electrons (carried by Oxygen bonds with 2 electrons (carried by Hydrogen) to produce waterHydrogen) to produce water

e-e-

ADP

ADP

ADP

ADP

ATP

ATP

ATP

ATP

OH H

ChemiosmosisChemiosmosisThe energy the electrons lose The energy the electrons lose along the way moves Halong the way moves H++ out of out of the matrix and into the the matrix and into the intermembrane space of the intermembrane space of the mitochondrionmitochondrion

As HAs H++ ions diffuse through ions diffuse through the membrane, ATP the membrane, ATP synthase uses the energy synthase uses the energy to join ADP and a to join ADP and a phosphate group phosphate group ATP ATP

Aerobic Respiration: Total Energy Aerobic Respiration: Total Energy YieldYield

Glycolysis:Glycolysis:– 2 ATP (Net)2 ATP (Net)– 2 NADH 2 NADH 6 ATP 6 ATP

Krebs Cycle:Krebs Cycle:– 2 ATP2 ATP– 8 NADH 8 NADH 24 ATP (ETC) 24 ATP (ETC)– 2 FADH2 FADH22 4 ATP (ETC) 4 ATP (ETC)

TOTAL:TOTAL:– 8 ATP + 30 ATP 8 ATP + 30 ATP 38 ATP 38 ATP

Anaerobic EnvironmentsAnaerobic Environments

When no oxygen is present, the cell will When no oxygen is present, the cell will have to do one of two things:have to do one of two things:– Die due to the fact that there is no Oxygen to Die due to the fact that there is no Oxygen to

accept electrons at the end of oxidative, so no accept electrons at the end of oxidative, so no more NAD+ are mademore NAD+ are made

oror– They can undergo Fermentation:They can undergo Fermentation:

Lactic AcidLactic Acid

AlcoholicAlcoholic

FermentationFermentation

Takes place in the mitochondrial inner Takes place in the mitochondrial inner membranemembrane

Does not require oxygen to occurDoes not require oxygen to occur

Does not directly produce ATPDoes not directly produce ATP

Alcoholic FermentationAlcoholic Fermentation

Occurs in some BACTERIA and Occurs in some BACTERIA and YEASTYEAST

2 step process:2 step process:– Carbon dioxide is released from Carbon dioxide is released from

pyruvate (3-C), forming pyruvate (3-C), forming acetaldehyde (2-C)acetaldehyde (2-C)

– Acetaldehyde is reduced by Acetaldehyde is reduced by NADH (gains an electron), NADH (gains an electron), forming ethyl alcohol (ethanol)forming ethyl alcohol (ethanol)

– NADNAD++ is regenerated, thereby is regenerated, thereby allowing glycolysis to continueallowing glycolysis to continue

Used to produce beer and wineUsed to produce beer and wine

Lactic Acid FermentationLactic Acid Fermentation

Occurs in ANIMALSOccurs in ANIMALS

1 step process:1 step process:– Pyruvate is reduced by Pyruvate is reduced by

NADH (gains an electron), NADH (gains an electron), forming lactic acidforming lactic acid

NADNAD++ is regenerated, is regenerated, thereby allowing glycolysis thereby allowing glycolysis to continueto continue

Occurs in muscle cells, Occurs in muscle cells, causing muscle pain and causing muscle pain and fatiguefatigue