84
1 ENERGY & CELLULAR RESPIRATION

ENERGY & CELLULAR RESPIRATION

  • Upload
    jontae

  • View
    28

  • Download
    0

Embed Size (px)

DESCRIPTION

ENERGY & CELLULAR RESPIRATION. Metabolism. Sum total of all the chemical reactions within an organism. Anabolism. Putting molecules together to create polymers Energy in – endergonic _________________ _________________. Catabolism. Releases energy by breaking bonds - PowerPoint PPT Presentation

Citation preview

Page 1: ENERGY & CELLULAR RESPIRATION

1

ENERGY & CELLULAR RESPIRATION

Page 2: ENERGY & CELLULAR RESPIRATION

2

Metabolism• Sum total of all the chemical reactions

within an organism

Page 3: ENERGY & CELLULAR RESPIRATION

3

Anabolism• Putting molecules together to create

polymers• Energy in – endergonic• _________________• _________________

Page 4: ENERGY & CELLULAR RESPIRATION

4

Catabolism• Releases energy by breaking bonds energy out – exergonic• _____________________

Page 5: ENERGY & CELLULAR RESPIRATION

5

Three kinds of work by cells1. Mechanical – cilia, flagella, muscle

contractions2. Transport work – pumping mol.’s across

membranes against the gradient3. Chemical work – pushing endergonic rxn’s

that wouldn’t occur spontaneously– Ie. Synthesis of polymers from monomers

Page 6: ENERGY & CELLULAR RESPIRATION

6

ATP• Adenosine triphosphate - Adenosine -- nitrogen base and a ribose - Triphosphate -- 3 phosphate groups• Immediate & usable form of energy

needed for work• ATP produced during cellular respiration

Page 7: ENERGY & CELLULAR RESPIRATION

7

ATP continued• High energy covalent bond exists b/w

phosphates - A---P-----P-----P - Add water to break bond & get energy out - ATP + water Pi + E + ADP

- ADP + water Pi + E + AMP

Page 8: ENERGY & CELLULAR RESPIRATION

8

Types of reactions1. Oxidation – reduction reactions AKA Redox reactions2. Phosphorylation

Page 9: ENERGY & CELLULAR RESPIRATION

9

Redox Reactions• Reduction – gain of electron (reduces the charge)• Oxidation – loss of electrons

– Pg. 163

Page 10: ENERGY & CELLULAR RESPIRATION

10

Phosphorylation• Making an ATP from ADP

– ADP + Pi → ATP

• Two types: - Oxidative phosphorylation - Substrate level phosphorylation

Page 11: ENERGY & CELLULAR RESPIRATION

11

Oxidative Phosphorylation• Producing ATP using energy from redox

reactions of an electron transport chain

Page 12: ENERGY & CELLULAR RESPIRATION

12

Substrate Level Phosphorylation• Enzymes transfer a P from a substrate to

ADP thus making ATP

Page 13: ENERGY & CELLULAR RESPIRATION

13

Cellular Respiration• Catabolic pathways that break down organic

molecules for the production of ATP• Overall energy gain from 1 mol. of glucose 1. Equation for complete breakdown of glucose C6H12O6 + 6O2 6CO2 + 6H2 O + 36 ATP

2. AKA oxidation of glucose 3. Rate is 40% efficient

Page 14: ENERGY & CELLULAR RESPIRATION

14

Stages of Cellular Respiration• Glycolysis• Citric acid cycle aka Krebs• Oxidative Phosphorylation: electron

transport and chemiosmosis– The citric acid cycle and oxidative

phosphorylation are often referred to as Aerobic respiration and both occur in the mitochondria

Page 15: ENERGY & CELLULAR RESPIRATION

15

Glycolysis

• Splitting of the 6C glucose into two 3C compounds (pyruvate)

• Occurs in cytoplasm• Anaerobic process – no oxygen required

Page 16: ENERGY & CELLULAR RESPIRATION

16

Steps of glycolysis - Each step changes glucose & is catalyzed

by a specific enzyme - Some steps are rearrangement steps thus

producing isomers - Some are redox or phosphorylation

reactions.

Page 17: ENERGY & CELLULAR RESPIRATION

17

Glycolysis is divided into 2 parts

• Energy investment phase• Energy payoff phase

Page 18: ENERGY & CELLULAR RESPIRATION

18

Energy investment

Page 19: ENERGY & CELLULAR RESPIRATION

19

(PFK)

Energy investment

Page 20: ENERGY & CELLULAR RESPIRATION

20

• Step 3 -- Regulatory step - Uses enzyme PFK - ATP is an allosteric inhibitor of PFK - Therefore if ATP is abundant this step will be inhibited thus glycolysis stops - Is this a good thing?

Page 21: ENERGY & CELLULAR RESPIRATION

21

Energy investment

PGAL

Page 22: ENERGY & CELLULAR RESPIRATION

22

End of energy investment phase

• 2 ATP invested• Glucose is now 2 PGAL molecules

Page 23: ENERGY & CELLULAR RESPIRATION

23

Energy investment

PGAL

Page 24: ENERGY & CELLULAR RESPIRATION

24

Energy payoff phase

Page 25: ENERGY & CELLULAR RESPIRATION

25

Glycolysis - energy payoff phase• Step 6 - For every glucose molecules 2 PGAL enter - A dehydrogenase removes a pair of hydrogen

atoms (2 electrons and 2 protons) from PGAL - Dehydrogenase then delivers the 2 electrons and

1 proton to NAD + creating NADH - the other proton (H+) is released• Each PGAL yields 1 NADH so 2 NADH are

gained• Pi enters

Page 26: ENERGY & CELLULAR RESPIRATION

26

Energy payoff phase

Page 27: ENERGY & CELLULAR RESPIRATION

27

Energy payoff phase

Page 28: ENERGY & CELLULAR RESPIRATION

28

Energy payoff phase

Page 29: ENERGY & CELLULAR RESPIRATION

29

Page 30: ENERGY & CELLULAR RESPIRATION

30

Page 31: ENERGY & CELLULAR RESPIRATION

31

Summary of glycolysis

1. Began with glucose – a 6C sugar

2. End with 2 pyruvates – each pyruvate has 3C’s (the original 6C’s from glucose still there)

Page 32: ENERGY & CELLULAR RESPIRATION

32

Summary cont’d3. Invested 2 ATP’s – got 4 out so net gain of

2 ATP’s4. Two waters given off at step 95. Two NADH’s gained – electron carriers

that will eventually yield energy

Page 33: ENERGY & CELLULAR RESPIRATION

33

Net gain from glycolysis from a single glucose mol.

• 2 ATP’s -- energy carrier• 2 pyruvates -- energy carrier• 2 NADH -- energy carrier• 2 H2O -- waste

Page 34: ENERGY & CELLULAR RESPIRATION

34

2 possibilities for pyruvate* Path depends on presence of oxygen.* No oxygen – fermentation in cytosol* Sufficient oxygen – aerobic respiration :

pyruvate enters mitochondria

Page 35: ENERGY & CELLULAR RESPIRATION

35

Page 36: ENERGY & CELLULAR RESPIRATION

36

Aerobic respiration Oxidation of pyruvate to acetyl CoA - See pg. 170 fig. 9.10 - Small but important transition step –

allows pyruvate to enter mitochondria

Page 37: ENERGY & CELLULAR RESPIRATION

37

Page 38: ENERGY & CELLULAR RESPIRATION

38

Aerobic respiration cont’d• Pyruvate oxidized to release NADH and

CO2 (total 2 per glucose)• Takes place in matrix solution of

mitochondria – enzymes & coenzymes are present

Page 39: ENERGY & CELLULAR RESPIRATION

39

Total gain from oxidation of pyruvate step

• 2 CO2 -- waste• 2 NADH – energy carriers• 2 Acetyl CoA (to continue with respiration)

Page 40: ENERGY & CELLULAR RESPIRATION

40

Citric Acid Cycleaka Krebs Cycle

• Takes place in matrix solution• One acetyl CoA enters Krebs by bonding

with OAA to form citric acid• The CoA drops off the acetyl compound &

goes back to get another acetyl group • Citric acid can also inhibit PFK• See pg. 171

Page 41: ENERGY & CELLULAR RESPIRATION

41

Page 42: ENERGY & CELLULAR RESPIRATION

42

Page 43: ENERGY & CELLULAR RESPIRATION

43

Page 44: ENERGY & CELLULAR RESPIRATION

44

Citric Acid cycle summary• Into Citric Acid cycle - Acetyl CoA - NAD +

- FAD +

- ADP

Page 45: ENERGY & CELLULAR RESPIRATION

45

Citric Acid cont’d• Out of Citric Acid cycle per glucose mol. - 2 ATP - 6 NADH - 2 FADH - 4 CO2

Page 46: ENERGY & CELLULAR RESPIRATION

46

Citric Acid cont’d- OAA is regenerated to repeat the cycle- Glucose has been completely oxidized.

All C’s from original glucose mol. have been removed.

How many net ATP’s so far?

Page 47: ENERGY & CELLULAR RESPIRATION

47

Citric Acid cont’d• 4 total ATP’s gained thus far• 2 ATP from glycolysis• 2 ATP from Citric acid• What type of phosphorylation occurred in

glycolysis and Citric Acid cycle? - Substrate level phosphorylation

Page 48: ENERGY & CELLULAR RESPIRATION

Oxidative Phosphorylation• Production of ATP using energy from

electron transport chain (ETC)

48

Page 49: ENERGY & CELLULAR RESPIRATION

Electron Transport Chain

• A chain of molecules that pass an electron from one molecule to another

• Located across the intermembrane – members weave in and out of the matrix and intermembrane space

49

Page 50: ENERGY & CELLULAR RESPIRATION

50

ETC cont’d• Electrons that enter come from NADH and

FADH• Per glucose molecule what enters ETC?• 10 NADH’s - 2 from glycolysis - 2 from oxidation of pyruvate - 6 from Krebs• 2 FADH’s from Citric Acid cycle

Page 51: ENERGY & CELLULAR RESPIRATION

51

Page 52: ENERGY & CELLULAR RESPIRATION

52

Structure of ETC cont’d• Most components of ETC are proteins

called cytochromes (thus aka cytochrome chain)

• Q (ubiquinone) is the only one that is not a protein

• Electrons “fall” down an energy gradient from NADH to oxygen

• Electronegative oxygen “pulls” electrons down the chain.

Page 53: ENERGY & CELLULAR RESPIRATION

53

Structure of ETC cont’d• At the “bottom” O2 captures these electrons

along with hydrogen nuclei (H+) forming H2O.

Page 54: ENERGY & CELLULAR RESPIRATION

54

Page 55: ENERGY & CELLULAR RESPIRATION

55

Working ETC• Multiprotein complexes accept and then

donate electrons.• As they do this, they pump H+ from matrix

to intermembrane space

Page 56: ENERGY & CELLULAR RESPIRATION

56

• NADH deposits its electrons at the start thus the electrons from NADH pass 3 multiprotein complexes

• This pumps enough H+ to create energy for production of 3 ATP molecules

• FADH deposits its electrons farther down the chain and misses the 1st complex therefore fewer protons are being pumped into the space, therefore only 2 ATP’s made

Working ETC

Page 57: ENERGY & CELLULAR RESPIRATION

57

• * The 2 NADH’s from glycolysis made in cytosol are brought into mitochondria by shuttle

• The shuttle may cause the NADH to enter at the same location as the FADH.

Page 58: ENERGY & CELLULAR RESPIRATION

58

• 38 maximum• Or 36 depending on shuttle for NADH• How many ATP’s made through substrate

level phosphorylation?• 4• How many ATP’s made through Oxidative

Phosphorylation?• 34

Page 59: ENERGY & CELLULAR RESPIRATION

How does ETC make ATP?• Chemiosmosis

59

Page 60: ENERGY & CELLULAR RESPIRATION

60

Chemiosmosis• Coupling the redox reactions of ETC to

ATP synthesis• As e-’s are sent through ETC, H+ are

pumped across membrane from matrix to intermembrane space

Page 61: ENERGY & CELLULAR RESPIRATION

61

Chemiosmosis

• H+ flow through the multiprotein complexes from matrix to intermembrane space

• Protons then diffuse back into matrix through ATP synthase complexes - this powers ATP generation

• H+ move one by one into binding sites of the proteins causing a rotation

Page 62: ENERGY & CELLULAR RESPIRATION

62

Chemiosmosis cont’d• Some H + leak back through ATP synthase• This causes a proton gradient called the

proton motive force.

Page 63: ENERGY & CELLULAR RESPIRATION

63

Chemiosmosis cont’d• Structure of ATP synthase causes

conformational changes that activate sites where ADP & P join to form ATP.

• Much is hypothesized here. See fig. 9.14

Page 64: ENERGY & CELLULAR RESPIRATION

64

Page 65: ENERGY & CELLULAR RESPIRATION

65

Page 66: ENERGY & CELLULAR RESPIRATION

66

Page 67: ENERGY & CELLULAR RESPIRATION

67

Page 68: ENERGY & CELLULAR RESPIRATION

68

Page 69: ENERGY & CELLULAR RESPIRATION

69

Page 70: ENERGY & CELLULAR RESPIRATION

70

Anaerobic Respiration• Same process as aerobic resp. but uses

sulfate or nitrate as final H acceptor not oxygen.

Page 71: ENERGY & CELLULAR RESPIRATION

71

Regulation

• 3 substances that regulate cellular respiration:

- ATP inhibits PFK - Citric acid inhibits PFK - AMP stimulates PFK

Page 72: ENERGY & CELLULAR RESPIRATION

72

Oxidation of other organic molecules.

• fig. 9.20

Page 73: ENERGY & CELLULAR RESPIRATION

73

Biosynthesis• The above processes working in reverse to

create proteins, fats, carbs. (glycogen)

Page 74: ENERGY & CELLULAR RESPIRATION

74

Page 75: ENERGY & CELLULAR RESPIRATION

75

Page 76: ENERGY & CELLULAR RESPIRATION

76

Fermentation• Two types of fermentation 1. Alcohol ferm. -- yeast cells & bacteria 2. Lactic acid ferm. -- fungi & human

muscle cells

Page 77: ENERGY & CELLULAR RESPIRATION

77

Fermentation cont’d• Alcohol ferm. - Details fig. 9.18 - Glycolysis occurs first

Page 78: ENERGY & CELLULAR RESPIRATION

78

Page 79: ENERGY & CELLULAR RESPIRATION

79

Alcohol Fermentation cont’d2 steps: - 1. Pyruvic acid from glycolysis

releases CO2 & forms acetaldehyde

- 2. Acetaldehyde is reduced by NADH to ethyl alcohol and gives off H +

Page 80: ENERGY & CELLULAR RESPIRATION

80

Alcohol ferm. cont’d• NAD + is regenerated for glycolysis• Net gain - 2ATP from glycolysis - 2 H2O “ “

- 2 CO2

- 2 ethanol (ethyl alcohol)

Page 81: ENERGY & CELLULAR RESPIRATION

81

Page 82: ENERGY & CELLULAR RESPIRATION

82

Lactic acid ferm. One step: Pyruvate is reduced directly by NADH to

form lactate (lactic acid) Net gain: 2 ATP from glycolysis 2 H2O

2 lactates

Page 83: ENERGY & CELLULAR RESPIRATION

83

Lactic acid ferm. cont’d

• Muscles do this when O2 in high demand or in short supply

• Glycogen glucose pyruvate lactate

Page 84: ENERGY & CELLULAR RESPIRATION

84

Lactic acid ferm. cont’d• Results of formation of lactic acid a. Muscle fatigue b. Lactic acid build up c. Drop in pH of cells slows rxns. d. Lactic acid to liver to be resynthesized into pyruvic acidPyruvate glucose glycogen