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Chapter 7
How Cells Harvest Energy
7.1 Overview of Respiration
Autotrophs
Heterotrophs
Cellular respiration
Dehydrogenation
Redox reactions
Aerobic
Anaerobic
Fermentation
Electron carriers (NADH and FADH2)
Electron transport chains
ATP
Substrate level phosphorylation
Oxidative phosphorylation
7.2 Glycolysis: Splitting Glucose
Occurs in the cytoplasm
Breaks down glucose into 2 pyruvate molecules
First stage is endergonic
Second stage is exergonic
NET PRODUCTS:
2 molecules of pyruvate
2 ATP
2 NADH
2 H2O
7.3 The Oxidation of Pyruvate to Produce Acetyl-CoA
Occurs in the mitochondria
Formation of Acetyl-CoA
NET PRODUCTS:
2 CO2
2 NADH
7.4 Kreb’s Cycle
Occurs in the mitochondria
Cyclic pathway
NET PRODUCTS:
6 NADH
2FADH2
2 ATP
4 CO2
7.5 Electron Transport Chain and Chemiosmosis
Occurs in the mitochondria
NADH and FADH2 donate electrons producing ATP
ATP synthase
NET PRODUCTS:
34 ATP
4 H2O
7.6 Energy Yield of Aerobic Respiration
TOTAL NET YIELD FROM AEROBIC RESPIRATION:
Glycolysis 2ATP
Krebs 2 ATP
ETC 34 ATP
38 ATP
Energy yield can fluctuate.
***Your textbook provides a modified energy yield of 32 ATP due to alternate
calculations of ATP generated from electron carriers. We will discuss these alternate
calculations in class***
7.7 Regulation of Aerobic Respiration
feedback inhibition
7.8 Oxidation Without Oxygen
Anaerobic cellular respiration uses the same pathway already described, but it does not
use oxygen as its terminal electron acceptor
Fermentation
Starts with glycolysis
Ethanol fermentation:
Pyruvate is converted to acetaldehyde
Lactic Acid fermentation:
Converts pyruvate to lactate
7.9 Catabolism of Proteins and Fats
Proteins: amino group is removed as waste and carbon backbone goes into glycolysis
and/or Kreb’s
Fats: glycerol goes into glycolysis and carbon backbone goes into Kreb’s
7.10 Evolution of Metabolism
Carbon degradation
Glycolysis
Anoxygenic photosynthesis
Oxygen forming photosynthesis
Nitrogen fixation
Aerobic respiration