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Cellular Respiration Chapter 9.

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Presentation on theme: "Cellular Respiration Chapter 9."— Presentation transcript:

1 Cellular Respiration Chapter 9

2 Read “What happens to sugars” paragraph
Page 231 Read “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 Respiration The 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 equation After 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 processes Making ATP molecules

11 3 stages of cellular respiration
1. Glycolysis 2. citric acid cycle (also known as Krebs Cycle) 3. electron transport chain We 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 oxygen Glycolysis is anaerobic. Can occur with or without oxygen Formation of Acetyl co A, Citric acid cycle and ETC are aerobic Number and type of final products of cellular respiration depend on the aerobic or anaerobic path taken

13 Anaerobic and Aerobic Glycolysis 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 chain If 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 glycolysis 0 in the formation of acetyl CoA 2 Citric Acid cycle 32-34 Electron Transport Chain 36-38 ATP total

15 # of ATP produced by anaerobic respiration (fermentation)
2 To 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

16 Step 1 Glycolysis Page 231

17 What is Glycolysis Series 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 pyruvate Glucose 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 process Net 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 glycolysis Glucose+ 2 ATP = 2PGAL + 2ADP

23 Phase 2 of glycolysis Each 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”

24 NAD+ +2H= NADH

25 Nicotinamide Adenine Dinucleotide
NAD+ is a hydrogen or electron acceptor molecule Glycolysis produces molecules of NADH The electron carrier NAD+ forms NADH when it accepts 2 electrons NADH is the energy used to drive cellular respiration NADH 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 glycolysis Each of the 10 steps is facilitated by a different enzyme All reactions occur in the cytoplasm and can take place with or without oxygen

27 steps of glycolysis- summary
Occurs in cytoplasm of cell Glucose is broken down into 2 pyruvate molecules (3 carbons each) 2 ATP are consumed 4 ATP are produced Net gain of 2 ATP 2 NADH are produced which can be used to make more ATP later 2 molecules of water are produced FATE OF PYRUVATE: Oxygen present- pyruvate enters the mitochondria, is transformed into Acetyl-CoA and the Krebs cycle starts If there is no oxygen present, pyruvate is transformed into lactic acid or ethanol by the process of fermentation

28 10 steps of glycolysis Animation:

29 Glycolysis Product Summary
4 ATP (needed 2 to start so net gain of only 2) 2 NADH 2 molecules of pyruvic acid (pyruvate) 2 water molecules

30 Glycolysis equation

31 Proteins and lipids providing fuel for ATP production
Proteins (amino acids) and fats can enter the Krebs cycle to produce energy Each 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 glucose diagram

32 Glycolysis summary

33 ATP summary for Glycolysis
Starting with glucose, how many ATP are made using aerobic glycolysis? 6 Starting with glucose, how many ATP are made using anaerobic glycolysis? 2

34 Stage 2: Formation of Acetyl coenzyme A
Smallest stage Pyruvate molecules formed in glycolysis enter the MITOCHONDRIA if oxygen is present Pyruvate 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 formed Why are 2 NADH formed???? Because there are 2 pyruvate produced in glycolysis that enter stage two. 1 pyruvate=1NADH Acetyl CoA will enter the Citric Acid Cycle

36 Citric Acid Cycle page 233 Step 3

37 Citric Acid Cycle or KREBS cycle (step 3)
1930- British scientist Hans Krebs Requires oxygen- “aerobic” Occurs in inner space of mitochondria called MATRIX Yields NADH, FAD, and ATP Formation 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+= NADH FAD= FADH2



42 A-D page 233 A. the 2 carbon compound acetyl-CoA reacts with a 4 carbon compound called oxaloacetic acid to form citric acid which is a 6 carbon compound B. 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 produced D. 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 NADH Citric Acid cycle- 6 NADH, 2 FADH, 2 ATP Combined total: 4 ATP, 10 NADH, 2 FADH NADH and FADH enter the electron transport chain

46 “Value” of the Krebs Cycle
Yields only 2 ATP Yields 6 NADH and 2 FADH2….these are used in the ETC which is like “money in the bank”

47 Krebs cycle song

48 Cellular Respiration Lab
Day 1- set up Day 2- observe results

49 Cellular respiration ETC (step 4)
“Oxidative Phosphorylation” Occurs in Cristae of mitochondria Uses 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 FADH2 Chemiosmosis- “ATP synthesis”. Moving e- across semipermeable membranes, down a gradient Once inside the Cristae, high energy electrons are shuffled from one protein to another due to different electronegativity levels 3 ATP will be produced per NADH molecule 10 NADH enter the ETC, so 30 ATP are produced FADH yields 2 ATP each, so 4 ATP are produced

50 ATP summary Glycolysis =2 Formation of Acetyl CoA=0
Citric Acid Cycle (Krebs)= 2 ETC= (28-30 from NADH and 4 from FADH2) Total ATP per glucose molecule

51 Quiz tomorrow Identify 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 electrons Reduction- gain of electrons NAD+ to NADH is a reduction reaction NADH 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, NADH 3. CAC- occurs in mitochondria, starting material Acetyl CoA, water. End products carbon dioxide, NADH, ATP, FADH2 4. 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 again Two major types: lactic acid fermentation and alcoholic fermentation Figure 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 ATP The 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 ATP EX. 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

58 Fermentation lab

59 Photosynthesis and CR comparison
Page 237

60 Bozeman Biology Podcast

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