Lecture 19: Cellular Respiration.
By the end of this lecture you should be able to…
Describe respiration as a redox reaction.
Concepts and terms: reductant, oxidant, NADH
Describe the structure of mitochondria
Discuss the major components of cellular respiration.
Concepts and terms: glycolysis, Krebs cycle, electron transport
Describe the major inputs and products of each component of the respiratory pathway.
Describe chemiosmosis.
Concepts and terms: ATP synthase, proton gradient.
Contrast aerobic and anaerobic respiration.Concepts and terms: fermentation, lactic acid
Describe the role of inhibitors in studying respiratory biochemistry.
Assigned reading: Chapter 9 in the text.
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http://cellbio.utmb.edu/cellbio/mitochondria_1.htm#powerhouses
Mitochondria are the cells' power sources. Usually they are rod-shaped; however they can be round.
C6H12O6 + 6O2 6CO2 + 6 H2O
Cellular respiration:
• Electrons from food are transferred initially to NAD+• Some of the energy released from NADH is used to make ATP
NAD: nicotinamide adenine dinucleotide
http://ntri.tamuk.edu/cell/mitochondrion/glycpics.html
Substrate-level phosphorylationOxidative phosphorylation
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Figure 9.11 A closer look at the Krebs cycle (Layer 1)
Figure 9.11 A closer look at the Krebs cycle (Layer 2)
Figure 9.11 A closer look at the Krebs cycle (Layer 3)
Figure 9.11 A closer look at the Krebs cycle (Layer 4)
• The conversion of pyruvate and the Krebs cycle produces large quantities of electron carriers.
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Peter Mitchell (1920 - 1992) Nobel Laureate…
…1961 paper introducing the chemiosmotic hypothesis.
http://www.life.uiuc.edu/crofts/bioph354/lect11.html
Chemiosmosis
Proton-motive forceOxidative phosphorylation
• A protein complex, ATP synthase, in the cristae actually makes ATP from ADP and Pi.
• ATP used the energy of
an existing proton gradient to power ATP synthesis.– This proton gradient
develops between the intermembrane space and the matrix.
Copyright © 2002 Pearson Education, Inc., publishing as Benjamin Cummings
Fig. 9.14
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AerobicAnaerobic
During extreme exertion…
Initially, stored ATP is metabolized (~5mmol/kg muscle. It’s gone in about 5 s.
Then phosphocreatine is converted to ATP; gone in another 5 s.
Then glycolosis starts (anaerobic respiration)…oops, lactate accumulates.
Anaerobic respiration kicks in after about 2 min.
Feedback mechanisms control cellular respiration