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Cellular Respiration ch 8

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1 Cellular Respiration ch 8

2 Cellular Respiration Have you ever wondered why exactly you need to breathe?  What happens when you stop breathing?

3 Cellular respiration is the set of the metabolic reactions and processes that take place in the cells of organisms to convert biochemical energy from nutrients into adenosine triphosphate (ATP), and then release waste products. Mitochondria!

4 C6H12O6 + 6O2 -->6 CO2 + 6H2O + 36 ATP
C6H12O6 + 6O2 -->6 CO2 + 6H2O + 36 ATP

5 Heterotrophs  Autotrophs  How are they connected?
making energy & organic molecules from ingesting organic molecules glucose + oxygen  carbon + water + energy dioxide C6H12O6 6O2 6CO2 6H2O ATP + oxidation = exergonic Autotrophs Where’s the ATP? making energy & organic molecules from light energy So, in effect, photosynthesis is respiration run backwards powered by light. Cellular Respiration oxidize C6H12O6  CO2 & produce H2O fall of electrons downhill to O2 exergonic Photosynthesis reduce CO2  C6H12O6 & produce O2 boost electrons uphill by splitting H2O endergonic + water + energy  glucose + oxygen carbon dioxide 6CO2 6H2O C6H12O6 6O2 light energy + reduction = endergonic

6 O2 or no O2 Aerobic Respiration: requires oxygen (air) (breathing) Anaerobic Respiration: does not need oxygen (no air) (breathing)

7 AEROBIC = with oxygen, occurs in the presence of oxygen -  in mitochondira
Without oxygen, another path is taken ....this path is called fermentation,  or  Anaerobic = without oxygen, in cytosol

8 2. Kreb's Cycle (Citric Acid Cycle) 3. Electron Transport Chain
There are three stages 1.  Glycolysis 2.  Kreb's Cycle (Citric Acid Cycle) 3.  Electron Transport Chain

9 GLYCOLYSIS can occur without oxygen GLYCOLYSIS   =  "glyco - lysis "  is the splitting of a 6 carbon glucose into two pyruvates,  each having 3 carbons net yield of 2 ATP per glucose molecule net yield of 2 NADH per glucose molecule

10 What does cellular respiration produce? Does it need light?
QOD What does cellular respiration produce? Does it need light? What does anaerobic mean? What does aerobic mean? What is the equation for cellular respirations?

11 Stage 1: Glycolysis: Products: 2 ATP 2 NADH 2 Pyruvic Acids
Anaerobic = no O2 needed Occurs in cytoplasm Occurs in all organisms Net of 2ATP Products: 2 ATP 2 NADH 2 Pyruvic Acids

12 Stage 1: Glycolysis: Products: 2 ATP 2 NADH 2 Pyruvic Acids
Anaerobic = no O2 needed Occurs in cytoplasm Occurs in all organisms Net of 2ATP Products: 2 ATP 2 NADH 2 Pyruvic Acids

13 Equation for Cellular Respiration: oxidation & reduction
REDOX reactions in respiration release energy as breakdown organic molecules break C-C bonds strip off electrons from C-H bonds by removing H atoms C6H12O6  CO2 = the fuel has been oxidized electrons attracted to more electronegative atoms in biology, the most electronegative atom? O2  H2O = oxygen has been reduced couple REDOX reactions & use the released energy to synthesize ATP *Need mitochondria and enzymes to make this happen! O2 is 2 oxygen atoms both looking for electrons LIGHT FIRE ==> oxidation RELEASING ENERGY But too fast for a biological system C6H12O6 6O2 6CO2 6H2O 36ATP + oxidation reduction or 38

14 Mitochondria: power house
Label on your paper

15 2. Citric Acid or Krebs Cycle
Hans Krebs It is not necessary to know the individual steps occur ONLY if oxygen is present and the cell has mitochondria. In this stage of cellular respiration, the oxidation of glucose to CO2 is completed. (this is why we exhale carbon dioxide)

16 Acetyl CoA enters Krebs cycle
Pre Krebs: The pyruvic acid (C3) loses a C to CO2 and use a H + to form NADH and becomes Acetyl Co-A (C2). Simple put: Pyruvate is converted to Acetly CoA releases 2 CO2 reduces 2 NAD  2 NADH (moves e-) produces 2 acetyl CoA Acetyl CoA enters Krebs cycle

17 Products (per glucose)
Krebs Cycle Overview Citric acid Aerobic Occurs in the matrix (inner compartment) Products (per glucose) 2 ATP 6 CO2 8 NADH 2 FADH2. These energy carriers now enter the electron transport chain (ETC).

18 Count the C & electron carriers!
pyruvate acetyl CoA 3C 2C NADH NADH citrate 4C 6C 4C 6C reduction of electron carriers This happens twice for each glucose molecule CO2 Everytime the carbons are oxidized, an NAD+ is being reduced. But wait…where’s all the ATP?? NADH x2 5C 4C FADH2 CO2 4C 4C NADH ATP

19 3. Electron Transport System:
Oxidative Phosphorylation: process in which ATP is formed as a result of the transfer of electrons from NADH or FADH 2 to O 2 by a series of electron carriers. As opposed to photophosphorylation…. a) consists of a series of enzymes on the inner mitochondrial membrane b) electrons are released from NADH and from FADH2 and as they are passed along the series of enzymes, they give up energy which is used to fuel a process called chemiosmosis which drives ATP synthesis ETC

20 Does this picture look familiar?
You've seen this before in photosynthesis. Products: 34 ATP Animation of the ETC McGraw Hill Animation

21 McGraw Hill Animation

22 Cytochrome c oxidase complex FADH NADH
Coenzyme Q NAD dehydrogenase Bc complex Coenzyme c Cytochrome c oxidase complex FADH NADH ADP ATP synthase McGraw Hill Animation

23 FADH NADH H2O McGraw Hill Animation ADP NAD dehydrogenase Coenzyme Q
Bc complex Coenzyme c Cytochrome c oxidase complex FADH NADH H2O ADP ATP synthase McGraw Hill Animation

24 Cytochrome c oxidase complex FADH NADH
Coenzyme Q NAD dehydrogenase Bc complex Coenzyme c Cytochrome c oxidase complex FADH NADH H2O ADP ATP synthase McGraw Hill Animation

25 -net yield of 32 or 34 ATP per glucose molecule
- 6 H2O are formed when the electrons unite with O2* at the end of electron transport chain.  * We breath because we need oxygen as the final electron acceptor! The resulting ATP is able to leave the mitochondria by the ATP transport protein in the membrane. It goes to wherever it is needed in the cell. Without oxygen to serve as the final electron acceptor, the process shuts down.

26 Breakdown of One Glucose Molecule
Calculations from each: NADH= 2 or 3 ATP can be made FADH2= 2 ATP can be made 1. Glycolysis – Produces: 2 ATP 2 NADH 2. Krebs Cycle (including “pre-Kreb’s”) - Produces: 2 ATP 8 NADH FADH2 Total: 4ATP 10 NADH FADH2 3. ETC - Produces: x x 2 30 ATP ATP = 34 ATP Total: 4ATP + 34 ATP + a grand total of 38 ATP ! Theoretical Yield Determining the exact yield of ATP for aerobic respiration is difficult for a number of reasons. - bacteria may differ in their carriers in the ETC - the number of ATP generated per reduced NADH or FADH2 is not always a whole number. For every pair of electrons transported to the electron transport chain by a molecule of NADH, between 2 and 3 ATP are generated. For each pair of electrons transferred by FADH2, between 1 and 2 ATP are generated. For simplicity, however, we look at the theoretical maximum yield of ATP per glucose molecule oxidized by aerobic respiration.

27 Determining the exact yield of ATP for aerobic respiration is difficult for a number of reasons.
- bacteria may differ in their carriers in the ETC - the number of ATP generated per reduced NADH or FADH2 is not always a whole number. For every pair of electrons transported to the electron transport chain by a molecule of NADH, between 2 and 3 ATP are generated. For each pair of electrons transferred by FADH2, between 1 and 2 ATP are generated. For simplicity, however, we look at the theoretical maximum yield of ATP per glucose molecule oxidized by aerobic respiration.

28

29 Cellular Respiration Summary
1 4 2 - Each NADH produces 3 ATP - Each FADH2 produces 2 ATP 2 3 5 2 6net 2 7net 34 11 8NADH 9 10

30 Cellular Respiration Summary
2 NADH 2 FADH2 6 NADH - Each NADH produces 3 ATP - Each FADH2 produces 2 ATP 2 NADH 2 ATP 2 ATP net 2 ATP net 34 ATP possible 8 NADH 2 FADH2 6 CO2

31 What happens if you don’t get enough oxygen?
Fermentation: use of pyruvate to make minimal ATP when there is no O2 = anaerobic This happens when the Krebs cycle cannot occur due to lack of oxygen By products of fermentation include lactic acid and alcohol Lactic Acid in muscle cells can cause muscle cramps.

32 Two Types: Lactic Acid Fermentation: in animals, turns pyruvate into lactic acid Alcoholic Fermentation: in yeast and bacteria, turns pyruvate into ethyl alcohol

33 Lactic Acid Fermentation Alcoholic Fermentation

34 Fermentation This happens when the Krebs cycle cannot occur due to lack of oxygen Byproducts of fermentation include lactic acid and alcohol Lactic Acid in muscle cells can cause muscle cramps.

35 Fermentation Applications of fermentation
This happens when the Krebs cycle cannot occur due to lack of oxygen Byproducts of fermentation include lactic acid and alcohol Lactic Acid in muscle cells can cause muscle cramps. Fermentation is used in making food products and alcohol products.  Applications of fermentation

36 Aka/ Other Vocab: Oxidative Phosphorylation: (aka ETC of cellular respirations) process in which ATP is formed as a result of the transfer of electrons from NADH or FADH 2 to O 2 by a series of electron carriers. Pre Kreps = Prep Reactions Kreb Cycle= Citric Acid Cycle Why? Substrate Level ATPsynthase= glycolysis and Kreb cycle together GTP: Guanosine-5'-triphosphate- GTP is involved in energy transfer within the cell, a GTP molecule is generated by one of the enzymes in the citric acid cycle. This is leads to the generation of one molecule of ATP, since GTP is readily converted to ATP.

37 Why is it called the citric acid cycle?

38 Is the Mitochondrial Genome Still Functional?
Evidence of Endosymbiosis: Mitochondrial genomes are very small and show a great deal of variation as a result of divergent evolution. Mitochondrial genes that have been conserved across evolution include rRNA genes, tRNA genes, and a small number of genes that encode proteins involved in electron transport and ATP synthesis. The mitochondrial genome retains similarity to its prokaryotic ancestor, as does some of the machinery mitochondria use to synthesize proteins. In fact, mitochondrial rRNAs more closely resemble bacterial rRNAs than the eukaryotic rRNAs found in cell cytoplasm. In addition, some of the codons that mitochondria use to specify amino acids differ from the standard eukaryotic codons.

39 Mitochondrial Disease
In school, children with mitochondrial disease often seem to work in “spurts” and then “peter out,” becoming lethargic and finding it difficult to concentrate. It ranges from intermittent difficulty thinking, remembering, moving and acting, to severe handicaps. Some results may be fatigue, muscle weakness and diabetes. What do you think, at the molecular level, is causing these symptoms?

40 What are the 3 stages of cellular respiration?
1.  2.  3. 

41 Food for thought 1. What is the purpose of cellular respiration?
2. Where does cellular respiration occur within the cell? 3. What is the waste product of cellular respiration? Would you go to an oxygen bar?

42

43 4. Compare Photosynthesis to Respiration
a.  Where does each occur? b.   What are the products of each? c.   What compounds are needed to start the processes? d.  What is the function of the electron transport chain in each process e.  Describe the role of ATPase in both processes.            

44 Photosynthesis – Respiration Cycle

45 Photophosphorylation vs Oxidative Phosphorylation:

46 Self Test 1. In order to produce energy, cells start with glycolysis. If oxygen is NOT present after glycolysis, what process occurs next?  a) Electron Transport Chain   b) Krebs Cycle   c) Fermentation 2. If oxygen IS present after glycolysis, what process occurs next?  a) Electron Transport Chain b) Krebs Cycle    c)Fermentation 3. A process that does NOT require oxygen is known as what?             a) Aerobic           b) Anaerobic 4. In glycolysis, glucose is broken into 2 molecules of __________________ acid 5.  Where does the Kreb's cycle occur? _________________ 6.   What gas is a waste product produced in the Krebs cycle? ____

47 7.  What enzyme is used in the electron transport chain to create ATP?
a.  citric acid          b. pyruvate             c. ATPase 8.  Where does glycolyis occur? a.  cytoplasm              b.  mitochondria          c.  chloroplast 9.  Which process produces the largest amount of ATP? a.  fermentation          b.  Krebs Cycle            c.   ETC 10.  The oxygen required by cellular respiration is reduced and becomes part of which molecule? a.  ATP                b. CO2            c.  H20

48 The Mystery of the Seven Deaths
Case Study: http://sciencecases.lib.buffalo.edu/cs/files/cellular_respiration.pdf In this case study, students learn about the function of cellular respiration and the electron transport chain and what happens when that function is impaired. Students play the role of medical examiner as they analyze the autopsy results to determine the cause of the mysterious deaths of these seven victims.  Explain the overall purpose of cellular respiration. Describe the intermediate metabolites of cellular respiration. Explain the function and importance of the electron transport chain. Describe the role of oxygen in cellular respiration

49 trophic level: each step in a food chain or food web, feeding level
Third level Consumer Secondary Consumers Primary Consumer Producer

50 90% is used for metabolic activity and is given off as heat.
Tropic levels 10% of the energy at one trophic level is available for organisms at the next trophic level. 90% is used for metabolic activity and is given off as heat. Tropic levels clip


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