The Living World Chapter 5

1
Cellular Respiration Harvesting Chemical
Energy Chapter 9
Associate Professor Pamela L. Pannozzo Principles
of Biology I BSC 1010
2
(No Transcript)
3
Cellular Respiration

• Occurs in the
• Cytoplasm and mitochondria of plant, animal,
  fungi, and protist cells
• Carbohydrates, proteins, fats can all fuel
  cellular respiration

C6H12O6 6O2 gt 6CO2 6H2O energy (heat/ATP)
4
Cellular Respiration
5
Cellular Respiration is a Redox Reaction
6
Transfers of Electrons are Transfers of Energy
7
(No Transcript)
8
(No Transcript)
9
Coenzyme NAD

• Electron acceptor
• Breaks fall of electrons into small energy steps

10
Step-wise Chemical Reactions
11
3 Cellular Respiration Stages

• Glycolysis
• Occurs in the cytosol
• No O2 required
• Glucose catabolism to 2 pyruvate
• 2 Net ATP formed via substrate phosphorylation 2
  NADH take electrons to electron transport chain
• Citric Acid (Krebs) Cycle
• Occurs in the mitochondrial matrix
• O2 required CO2 released
• Pyruvate catabolism to acetyl coenzyme A
• 2 Net ATP formed via substrate phosphorylation
  8 NADH/2 FADH2 take electrons to electron
  transport chain
• Oxidative Phosphorylation
• Occurs in the inner mitochondrial membrane
• O2 required
• 32/34 ATP formed via chemiosmosis
• Steps
• Electron transport
• Chemiosmosis

12
(No Transcript)
13
Glycolysis

• Glucose catabolized into pyruvate
• Only small amount of energy released
• 2 NADH carry electrons to electron transport

14
Glycolysis
15
(No Transcript)
16
(No Transcript)
17
Citric Acid (Krebs) Cycle

• Pyruvate derivative converted into acetyl CoA,
  CO2 given off
• Acetyl CoA converted into intermediary compounds
• 2 ATP, 8 NADH, and 2 FADH2 produced

18
(No Transcript)
19
(No Transcript)
20
Oxidative Phosphorylation

• Electrons from NADH and FADH2 transferred to
  electron transport chain molecules, to O2
• H pumped from mt matrix to mt intermembrane
  space
• Back flow of H into mt matrix (exergonic proton
  motive force) through ATP synthase provides
  energy for phosphorylation of ADP (chemiosmosis)
• 32-34 ATP produced

21
ATP The Energy Currency of the Cell
Used to power many of the cells activities
Provided through photosynthesis or aerobic
respiration
22
(No Transcript)
23
ATP Yield Per Glucose Molecule
24
Efficiency of Cellular Respiration

• 40 energy of glucose turned to ATP, 60 lost as
  heat
• Automobile gasoline combustion 25 energy
  converted to mechanical energy 75 lost as heat

25
Anaerobic Cellular Respiration Fermentation

• A pathway for cells to oxidize organic fuel and
  produce ATP without oxygen
• Generates less ATP than aerobic cellular
  respiration
• Common Types
• Lactic acid fermentation (end product 2 lactate)
• Alcohol fermentation (end product 2 Ethanol)
• Steps
• Glycolysis oxidizes glucose to pyruvate
• NAD acts as intermediate electron acceptor
• Final electron acceptor is pyruvate or
  acetaldehyde
• Regenerates NAD from NADH

26
(No Transcript)
27
(No Transcript)
28
Versatility of Catabolism
29
Control of Cellular Respiration

• Negative Feedback for Anabolic Enzyme Production
• Speed of Catabolic Cellular Respiration
• Allosteric inhibition and activation at various
  steps in the metabolic pathway

30
(No Transcript)