2 Read “What happens to sugars” paragraph Page 231Read “What happens to sugars” paragraph
3 Animals, fungi, protozoa and most bacteria are unable to perform photosynthesis and therefore must rely on the carbohydrates formed in plants to obtain the energy necessary for their metabolic processes.
5 Cellular RespirationThe process by which the MITOCHONDRIA break down food molecules to produce ATP
6 Another definition…..Controlled release of energy in the form of ATP from organic compounds in cells
7 Taking a closer look into the mitochondria , “Power house of the cell”
8 mitochondria 2 membrane layers- outer and inner Cristae- folds of inner membrane to increase surface area. Where reactions occur.Matrix is the fluid inside
9 equationAfter the three steps in cellular respiration glucose and oxygen are turned into carbon dioxide, water, and energy in the following equation:C6H12O6 + 6O2 --> 6CO2 + 6H2O + energy
10 Energy produced is used for: Body processesMaking ATP molecules
11 3 stages of cellular respiration 1. Glycolysis2. citric acid cycle (also known as Krebs Cycle)3. electron transport chainWe will learn the process in 4 steps: add “formation of acetyl coenzyme A” between glycolysis and CAC
12 Aerobic or Anaerobic Anaerobic- process which does not require oxygen Aerobic- process which does require oxygenGlycolysis is anaerobic. Can occur with or without oxygenFormation of Acetyl co A, Citric acid cycle and ETC are aerobicNumber and type of final products of cellular respiration depend on the aerobic or anaerobic path taken
13 Anaerobic and AerobicGlycolysis does not require oxygen. It can occur with or without oxygen.If oxygen is present, the pyruvate will enter the citric acid cycle and electron transport chainIf oxygen is absent, fermentation will occur. Fermentation will be covered in detail at the end of this unit
14 # ATP produced by AEROBIC Cellular Respiration 2 ATP glycolysis0 in the formation of acetyl CoA2 Citric Acid cycle32-34 Electron Transport Chain36-38 ATP total
15 # of ATP produced by anaerobic respiration (fermentation) 2To perform the same amount of work, an anaerobic cell must consume up to 20 times as much glucose or other carbohydrate as a cell using aerobic respiration
17 What is GlycolysisSeries of chemical reactions in the cytoplasm of a cell that break down glucose (a six carbon sugar) into two molecules of PYRUVIC ACID or PYRUVATE (a three carbon compound)
18 *****Glycolysis occurs in the CYTOPLASM of the cell******
19 Glycolysis is responsible for the production of ATP through the degradation of glucose. It is a fundamental reaction performed by all organisms where glucose is turned into pyruvate.Converts 1 glucose to 2 pyruvateGlucose is a 6 carbon sugar and pyruvate is a 3 carbon sugar (3x2=6)
20 Glycolysis uses and makes ATP Requires 2 molecules of ATP to start glycolysis- to “activate glucose”Makes 4 molecules in the processNet 2 molecules of ATP produced for each molecule of glucose broken down
21 2 major phases of glycolysis Phase 1 details:phosphate is added to the glucose. Process known as “phosphorylation”.Glucose splits forming 2 molecules of PGAL which requires 2 ATP
22 Phase 1 of glycolysisGlucose+ 2 ATP = 2PGAL + 2ADP
23 Phase 2 of glycolysisEach PGAL is oxidized by the removal of 2 hydrogen atoms. Each PGAL is transformed into a molecule of PYRUVATE.This produces 4 ATP in a process known as “substrate level phosphorylation”
25 Nicotinamide Adenine Dinucleotide NAD+ is a hydrogen or electron acceptor moleculeGlycolysis produces molecules of NADHThe electron carrier NAD+ forms NADH when it accepts 2 electronsNADH is the energy used to drive cellular respirationNADH temporarily stores large amounts of free energy. The free energy comes from hydrogen atoms being removed from atoms (chemical bonds being broken)During glycolysis, 2 NADH are produced
26 10 steps of glycolysisEach of the 10 steps is facilitated by a different enzymeAll reactions occur in the cytoplasm and can take place with or without oxygen
27 steps of glycolysis- summary Occurs in cytoplasm of cellGlucose is broken down into 2 pyruvate molecules (3 carbons each)2 ATP are consumed4 ATP are producedNet gain of 2 ATP2 NADH are produced which can be used to make more ATP later2 molecules of water are producedFATE OF PYRUVATE:Oxygen present- pyruvate enters the mitochondria, is transformed into Acetyl-CoA and the Krebs cycle startsIf there is no oxygen present, pyruvate is transformed into lactic acid or ethanol by the process of fermentation
31 Proteins and lipids providing fuel for ATP production Proteins (amino acids) and fats can enter the Krebs cycle to produce energyEach gram of lipid contains more than twice as much energy as 1 gram of glucose or amino acids because lipids have a lot of hydrogen atoms……can yield up to 44 ATP as compared to from glucosediagram
33 ATP summary for Glycolysis Starting with glucose, how many ATP are made using aerobic glycolysis?6Starting with glucose, how many ATP are made using anaerobic glycolysis?2
34 Stage 2: Formation of Acetyl coenzyme A Smallest stagePyruvate molecules formed in glycolysis enter the MITOCHONDRIA if oxygen is presentPyruvate will be converted to Acetyl CoEnzyme A
35 Conversion of pyruvate to Acetyl Co A Each pyruvate is oxidized to a 2 carbon molecule called “acetate”Acetate will combine with coenzyme A forming “acetyl coenzyme A”Carbon dioxide and 2NADH also formedWhy are 2 NADH formed????Because there are 2 pyruvate produced in glycolysis that enter stage two. 1 pyruvate=1NADHAcetyl CoA will enter the Citric Acid Cycle
37 Citric Acid Cycle or KREBS cycle (step 3) 1930- British scientist Hans KrebsRequires oxygen- “aerobic”Occurs in inner space of mitochondria called MATRIXYields NADH, FAD, and ATPFormation of Acetyl Co A is a Prepatory Step: Takes the 2 pyruvates produced in glycolysis and, thru the process of pyruvate oxidation, alters the pyruvate to form acetyl Co A. CO2 is released and NADH is formed.
38 Page 233- Citric Acid Cycle Diagram The citric acid cycle breaks down a molecule of acetyl- Co A and forms ATP and CO2. The electron carriers NAD+ and FAD pick up energized electrons and pass them to the electron transport chain in the matrix of the mitochondria.
39 Flavin adenine dinucleotide Hydrogen and electron acceptor compound. Captures energy and stores it like NAD+.NAD+= NADHFAD= FADH2
42 A-D page 233A. the 2 carbon compound acetyl-CoA reacts with a 4 carbon compound called oxaloacetic acid to form citric acid which is a 6 carbon compoundB. a molecule of CO2 is formed, reducing citric acid from 6 carbons to 5 carbons. In the process, a molecule of NADH and H+ is produced.
43 C. another molecule of CO2 is released, forming a 4 carbon compound C. another molecule of CO2 is released, forming a 4 carbon compound. A molecule of ATP and NADH are also producedD. the 4 carbon molecule goes through a series of reactions in which FADH2, NADH, and H+ are formed. The carbon chain is rearranged, and oxaloacetic acid is again made available for the cycle.
44 Krebs cycle goes around TWO times Once for each acetyl CoA or per one glucose
45 Product summary Glycolysis- 2 ATP, 2 pyruvates, 2 NADH Formation of Acetyl CoA- 2 NADHCitric Acid cycle- 6 NADH, 2 FADH, 2 ATPCombined total: 4 ATP, 10 NADH, 2 FADHNADH and FADH enter the electron transport chain
46 “Value” of the Krebs Cycle Yields only 2 ATPYields 6 NADH and 2 FADH2….these are used in the ETC which is like “money in the bank”
48 Cellular Respiration Lab Day 1- set upDay 2- observe results
49 Cellular respiration ETC (step 4) “Oxidative Phosphorylation”Occurs in Cristae of mitochondriaUses electron carrier molecules called NAD+ and FAD. These molecules carry energy (hydrogen electrons)Reminder: NAD+ forms from NADH when it accepts two electrons. FAD forms FADH2Chemiosmosis- “ATP synthesis”. Moving e- across semipermeable membranes, down a gradientOnce inside the Cristae, high energy electrons are shuffled from one protein to another due to different electronegativity levels3 ATP will be produced per NADH molecule10 NADH enter the ETC, so 30 ATP are producedFADH yields 2 ATP each, so 4 ATP are produced
50 ATP summary Glycolysis =2 Formation of Acetyl CoA=0 Citric Acid Cycle (Krebs)= 2ETC= (28-30 from NADH and 4 from FADH2)Total ATP per glucose molecule
51 Quiz tomorrowIdentify where each of the ATP are produced in aerobic cellular respiration
52 Oxidative Phosphorylation Animation Interactive animation to try at home
53 “REDOX” Redox- oxidation/reduction reaction Oxidation- loss of electronsReduction- gain of electronsNAD+ to NADH is a reduction reactionNADH to NAD+ is an oxidation reaction
54 Summary of Aerobic Respiration 1. Glycolysis- occurs in cytosol. Starting material glucose, ATP, NAD+, end products pyruvate, ATP (2 net), NADH.2. formation of acetyl co A- occurs in mitochondria. Starting material- pyruvate, coenzyme A, end products Acetyl CoA, carbon dioxide, NADH3. CAC- occurs in mitochondria, starting material Acetyl CoA, water. End products carbon dioxide, NADH, ATP, FADH24. ETC- occurs in mitochondria, starting material NADH, FADH2, oxygen. End products ATP and water
55 Fermentation Anaerobic process Follows glycolysis Provides means to continue producing ATP until oxygen is available againTwo major types: lactic acid fermentation and alcoholic fermentationFigure 9.12 page 235
56 Lactic acid fermentation Two molecules of pyruvic acid produced by glycolysis use NADH to form two molecules of lactic acid and two molecules of ATPThe lactic acid is transferred from muscle cells, where it is produced during strenuous exercise (resulting in muscle fatigue) , to the liver that converts it back to pyruvic acid
57 Alcoholic fermentation Used by yeast cells and some bacteria to produce CO2, ethyl alcohol, and 2 ATPEX. When making bread, yeast cells produce CO2 that forms bubbles in the dough.Oven heat kills the yeast and the bubble pockets are left to lighten the bread
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