Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings Essential Idea Cell respiration supplies energy for the functions of life.

Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings Understanding Cell respiration is the controlled release of energy from organic compounds to produce ATP. ATP from cell respiration is immediately available as a source of energy in the cell. Anaerobic cell respiration gives a small yield of ATP from glucose. Aerobic cell respiration requires oxygen and gives a large yield of ATP from glucose.

Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings IB Assessment Statement Define cell respiration. GuQhttp:// GuQ

Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings

Define Respiration Cell respiration is the controlled release of energy from organic compounds in cells to form ATP. ATP or Adenosine triphosphates is the molecule which directly fuels the majority of biological reactions. – Everyday each person will hydrolyse (reduce) ATP molecules to ADP. – The ADP is reduced back to ATP using the free energy from the oxidation of organic molecules.

ATP = Life’s energy currency $$$$ ATP (adenosine triphosphate) is the cell’s energy shuttle ATP provides energy for cellular functions

Copyright Pearson Prentice Hall Chemical Energy and ATP ATP consists of: – adenine – ribose (a 5-carbon sugar) – 3 phosphate groups Adenine ATP Ribose 3 Phosphate groups

Copyright Pearson Prentice Hall Chemical Energy and ATP Storing Energy ADP has two phosphate groups instead of three. A cell can store small amounts of energy by adding a phosphate group to ADP. ADP ATP Energy Partially charged battery Fully charged battery + Adenosine Diphosphate (ADP) + Phosphate Adenosine Triphosphate (ATP)

Copyright Pearson Prentice Hall Chemical Energy and ATP Releasing Energy Energy stored in ATP is released by breaking the chemical bond between the second and third phosphates. P ADP 2 Phosphate groups

The bonds between the phosphate groups of ATP’s tail can be broken by hydrolysis Energy is released from ATP when the terminal phosphate bond is broken Adenosine triphosphate (ATP) Energy PP P PP P i Adenosine diphosphate (ADP)Inorganic phosphate H2OH2O + +

The Regeneration of ATP ATP is a renewable resource that is regenerated by addition of a phosphate group to ADP The energy to phosphorylate ADP comes from catabolic reactions in the cell The chemical potential energy temporarily stored in ATP drives most cellular work P i ADP Energy for cellular work (endergonic, energy- consuming processes) Energy from catabolism (energonic, energy- yielding processes) ATP +

Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings Chemical Energy Transfer Food to ATP

Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings The Pathways of cellular respiration and Production of ATP There are several steps to the process of cellular respiration but the overall chemical equation is below: C 6 H 12 O 6 + 6O 2 --> 6CO 2 + 6H 2 O + Energy (ATP + heat) Overall this equation states that glucose reacts with oxygen to form/ produce carbon dioxide and water Note: Cellular respiration releases energy. It is therefore a exothermic (exergonic) reaction.

Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings IB Assesment Statement State that, in cell respiration, glucose in the cytoplasm is broken down by glycolysis into pyruvate, with a small yield of ATP.

The Stages of Cellular Respiration: A Preview Cellular respiration has three stages: 1.Glycolysis (breaks down glucose into two molecules of pyruvate) 2.The citric acid cycle/ Krebs Cycle (completes the breakdown of glucose) 3.Oxidative phosphorylation (accounts for most of the ATP synthesis) The latter process generates most of the ATP is called oxidative phosphorylation because it is powered by redox reactions

Glycolysis harvests energy by oxidizing glucose to pyruvate Glycolysis (“splitting of sugar”) breaks down glucose into two molecules of pyruvate Glycolysis occurs in the cytoplasm Requires NO oxygen and so is considered an Anaerobic Reaction The overall reaction for glycolysis is for every one molecule of glucose used: – 2 molecules of Pyruvate are formed – 2 net molecules of ATP are formed – 2 molecules of NADH are formed

Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings Glycolysis Location: Cytoplasm Process: Glycolysis Substrate: Glucose Products: 2 Pyruvate and a small amount of ATP Glycolysis does not use oxygen.

Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings Glycolysis Animation Watch Animation for more details: hill.com/sites/ /student_view0/chapt er25/animation__how_glycolysis_works.html?is bn= &firstName=&MI=&lastName= &my =&myStyle=&prof =&profStyle= &ta =&taStyle=&other =&otherStyle= hill.com/sites/ /student_view0/chapt er25/animation__how_glycolysis_works.html?is bn= &firstName=&MI=&lastName= &my =&myStyle=&prof =&profStyle= &ta =&taStyle=&other =&otherStyle

Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings IB Assessment Statement Explain that, during anaerobic cell respiration, pyruvate can be converted in the cytoplasm into lactate, or ethanol and carbon dioxide, with no further yield of ATP.

Fermentation allows glycolysis to continue. Fermentation is an anaerobic process. – occurs when oxygen is not available for cellular respiration – does not produce ATP Fermentation allows glycolysis to continue making ATP when oxygen is unavailable.

Pyruvate Glucose CYTOPLASM No O 2 present Fermentation Ethanol or lactate Acetyl CoA MITOCHONDRION O 2 present Cellular respiration Citric acid cycle There are two types of Fermentation/ anaerobic respiration 1.Lactic Acid Fermentation 2.Alcoholic Fermentation

Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings Anaerobic Respiration Anaerobic respiration is the oxidation of organic compounds without oxygen. It is less efficient than aerobic respiration (with oxygen). There are different types of anaerobic respiration. Here we will compare anaerobic respiration in yeast and humans.

Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings Humans anaerobic respiration Location: cytoplasm Substrate: Glucose Product: lactic acid (lactate) + ATP Note: lactic anaerobic respiration supplements aerobic respiration in the production of ATP. Both aerobic and anaerobic respiration can take place in the human cell at the same time

Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings Humans anaerobic respiration

Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings Exercise and anaerobic respiration : Human lactic anaerobic respiration is a process that supplements the production of ATP. The lactic pathway is so inefficient that under normal circumstances it cannot produce enough energy to support human systems. In describing the lactic pathway it is often suggested that sprinters 'do not breath during the 100m sprint' (they do, just watch any video) and they only produce ATP for running from the lactic pathway. This is a mis-representation of a complex response to the demand for ATP. It is far better to consider that anaerobic respiration in humans supplements (adds to) the aerobic production of ATP.

Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings Yeast anaerobic respiration: Location: cytoplasm Substrate: Glucose Product: Ethanol + carbon dioxide + ATP This is the end point for this fermentation reaction. Ethanol and CO 2 are both excreted with no further metabolism of the energy stored in the ethanol (very inefficient) Note: The glucose molecule has been hydrolysed further than in human respiration. Some organisms are totally anaerobic others can switch between anaerobic and aerobic.

Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings Yeast anaerobic respiration:

Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings Anaerobic respiration: Fermentation respiration in yeast yields two useful products from a human perspective. The carbon dioxide can be used in a variety industrial processes the best known of which is to raise bread. Many Brewers of alcohol will bottle the CO 2 for use in the 'carbonation' of other drink products. The alcohol itself is of course the basis of many industries such as beer brewing. In more recent time the use of fermentation products is being used as an alternative source of fuel such as is the case in fuel for automobiles.

Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings IB Assessment Statement Explain that, during aerobic cell respiration, pyruvate can be broken down in the mitochondrion into carbon dioxide and water with a large yield of ATP

Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings

Aerobic Respiration Location: Mitochondria Substrate: Pyruvate Products: ATP, Carbon dioxide, water and heat. The production of ATP in the aerobic pathway is much greater than in either glycolysis or the anaerobic alternatives. The oxygen breathed in during ventilation is sent form the lung into the blood and then transported to the cell. The oxygen diffuses into the cell and then into the mitochondria for aerobic respiration

Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings Aerobic Respiration This diagram is a summary of the complete aerobic pathway. The by-product carbon dioxide is excreted and of course the heat produced is important in thermoregulation

Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings Aerobic Respiration (a) Glucose transported to the cell diffuses into the cytoplasm. Glucose is the initial substrate for respiration. (b) Glycolysis in which glucose with six carbons is broken down into two Pyruvate each with 3 carbons. This yields a small amount of ATP.

Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings Aerobic Respiration (c) Anaerobic respiration in which lactic acid is produced, oxidation from glucose yields a small amount of ATP. Remember that anaerobic respiration will occur at the same time as aerobic respiration to provided more energy. (d) Aerobic respiration in which pyruvate is broken down, oxidised, further in the mitochondria where a lot of ATP is produced.

Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings Aerobic Respiration (e) Oxygen is required for step (d)to be completed. This is transported to the cell on the haemoglobin found inside red blood cells. (f) carbon dioxide is produced as waste from aerobic respiration it diffuses into the blood and is transported to the lungs where it is excreted in exhaled air.

LE 9-6_1 Mitochondrion Glycolysis Pyruvate Glucose Cytosol ATP Substrate-level phosphorylation

LE 9-6_2 Mitochondrion Glycolysis Pyruvate Glucose Cytoplasm ATP Substrate-level phosphorylation ATP Substrate-level phosphorylation Krebs cycle

LE 9-10 CYTOPLASM Pyruvate NAD + MITOCHONDRION Transport protein NADH + H + Coenzyme ACO 2 Acetyl Co A

LE 9-6_3 Mitochondrion Glycolysis Pyruvate Glucose Cytosol ATP Substrate-level phosphorylation ATP Substrate-level phosphorylation Citric acid cycle ATP Oxidative phosphorylation Oxidative phosphorylation: electron transport and chemiosmosis Electrons carried via NADH Electrons carried via NADH and FADH 2

This is all occur in the folds of the inner membrane of the mitochondria 6H O 2 6CO 2 6O 2 mitochondrion matrix (area enclosed by inner membrane) inner membrane ATP energy energy from glycolysis and

LE 9-16 CYTOSOL Electron shuttles span membrane 2 NADH or 2 FADH 2 MITOCHONDRION Oxidative phosphorylation: electron transport and chemiosmosis 2 FADH 2 2 NADH6 NADH Citric acid cycle 2 Acetyl CoA 2 NADH Glycolysis Glucose 2 Pyruvate + 2 ATP by substrate-level phosphorylation + 2 ATP by substrate-level phosphorylation + about 32 or 34 ATP by oxidation phosphorylation, depending on which shuttle transports electrons form NADH in cytosol About 36 or 38 ATP Maximum per glucose:

LE 9-18 Pyruvate Glucose CYTOSOL No O 2 present Fermentation Ethanol or lactate Acetyl CoA MITOCHONDRION O 2 present Cellular respiration Citric acid cycle

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Practice Questions Compare anaerobic and aerobic respiration

Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings

Skills and Applications Application: Use of anaerobic cell respiration in yeasts to produce ethanol and carbon dioxide in baking. Application: Lactate production in humans when anaerobic respiration is used to maximize the power of muscle contractions. Skill: Analysis of results from experiments involving measurement of respiration rates in germinating seeds or invertebrates using a respirometer.