Lecture 19: Cellular Respiration'

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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 Discus
s the major components of cellular
respiration. Concepts and terms glycolosis,
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. Conce
pts and terms fermentation, lactic acid Describe
the role of inhibitors in studying respiratory
biochemistry and describe the processes of
alternative respiration in plants. Assigned
reading Chapter 9 in the text.
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Mitochondria are the cells' power sources. They
are distinct organelles with two membranes.
Usually they are rod-shaped, however they can be
round. The outer membrane limits the organelle.
The inner membrane is thrown into folds or
shelves that project inward. These are called
"cristae mitochondriales". This electron
micrograph taken from Fawcett, A Textbook of
Histology, Chapman and Hall, 12th edition, 1994,
shows the organization of the two membranes.
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http//cellbio.utmb.edu/cellbio/mitochondria_1.htm
powerhouses
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http//cellbio.utmb.edu/cellbio/mitochondria_1.htm
Substructure
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C6H12O6 6O2 -gt 6 CO2 6H2O
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http//ntri.tamuk.edu/cell/mitochondrion/glycpics.
html
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http//ntri.tamuk.edu/cell/mitochondrion/glycol.ht
ml
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http//www.people.virginia.edu/rjh9u/krebs.html
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The cytochromes are small proteins, each carrying
a heme group with a single atom of iron. They are
thus able to carry only one electron.
Fe3 e- --gt Fe2
Three dimensional structure of reduced Cytochrome
c from Tuna. The heme group is shown in red, and
Fe in purple. The two structures shown (above)
are of cytochrome c the wire frame on the left
and a backbone model (which shows the peptide
bond backbone of the protein). http//www.biosci
.uq.edu.au/GMC/oxphos.html
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Peter Mitchell (1920 - 1992) Nobel
Laureate 1961 paper introducing the
chemiosmotic hypothesis.
http//www.life.uiuc.edu/crofts/bioph354/lect11.ht
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This image of the complete ATP synthase complex
from E. coli, using image averaging and
cryo-electron microscopy, and the model derived
from it. http//www.life.uiuc.edu/crofts/bioph354/
lect10.html
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http//www.wellesley.edu/Chemistry/chem227/metabol
ism/kreb/kreb.htm
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During extreme exertion Initially, stored ATP
is metabolized (5mmol/kg muscle. Its gone in
about 5 s. Then phosphocreatine is converted to
ATP gone in another 5 s. Then glycolysis starts
(anaerobic respiration)oops, lactate
accumulates. Aerobic respiration kicks in after
about 2 min.
American swimmer Dara Torres stretches during the
team's first practice in Sydney.
http//www.msnbc.com/news/458414.asp
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The Alternative Oxidase
http//www.plantphys.net/article.php?ch11id148
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http//www.plantphys.net/printer.php?ch11id126
Relationship of oxygen consumption rate and
inflorescence (spadix) temperature in Eastern
skunk cabbage Symplocarpus foetidus measured in
the field in Ontario, Canada. The points were
gathered at 24-minute intervals from a single
plant over a 5-day period. Peak respiration
occurs at a spadix temperature of about 18C,
which occurs at an ambient temperature of about
3C. Above this level, the cluster of points at
the upper right demonstrates the inverse
relationship between respiration and spadix
temperature. When ambient temperature dropped
below about 3C, however, heat production could
not be sustained, and spadix temperature dropped
quickly to just above ambient, resulting in the
cluster of points at the lower left. (Click image
to enlarge.)