Transcript Power, Sex, Suicide. Mitochondria and the Meaning

SBS922 Membrane Biochemistry
Mitochondria and chloroplasts
John F. Allen
School of Biological and Chemical Sciences, Queen Mary, University of
London
1
Look in course resources on SBS web site or go to
http://www.qmw.ac.uk/~ugbt120/mem_b.htm
Second Year : Membrane Biochemistry
Please look at Lecture summaries for Lectures 18,19 and 20 in Basic Biochemistry
above to recall the first year lectures
• Click here for a summary of Lecture 15 "An Introduction to Mitochondria.
Separation of mitochondrial compartments"
• Click here for a summary of Lecture 16 " Analysis of mitochondrial compartments
/ Proteins. Chloroplasts"
• Click here for a sample calculation of electron transfer rates in mitochondria in
Practical 3
• Click here for a summary of Lecture 17 "Observed characteristics of oxidative
phosphorylation"
•
Click here for a summary of Lecture 18 "Chemisosmotic hypothesis"
• Click here for a summary of Lecture 19 "Experimental evidence that satisfies
Mitchell's three essential requirements"
Bioenergetics, 3rd Edition
David Nicholls and Stuart J
Ferguson
Academic Press · Published July
2002
Recommended text for 3rd year
course Membrane Proteins.
Chapter 4 is good for Membrane
Biochemistry lectures and
practicals
Mitochondria (singular; mitochondrion).
– mitochondria power animal and plant cells
– mitochondria are "domesticated" bacteria
– during "domestication" - cell evolution - these bacteria
relinquished many genes to the nucleus of the host cell...
.…and there are now few left (13 in the case of vertebrates,
including mammals, including humans) encoding around 1 %
of mitochondrial proteins
And it is always the same 1 %.....
Why?
Scientific Art From
Lane, N. (2005)
Power, Sex, Suicide: Mitochondria and
the Meaning of Life
http://pages.britishlibrary.net/nick.lane/
Mighty Mitochondria
copyright Odra Noel
A mitochondrion—one of many tiny powerhouses within cells that control our lives in
surprising ways
copyright Ina Schuppe-Koistinen
Goodsell, D. S. The Machinery of Life. Springer-Verlag, New
York and Berlin, 1993
Allen, J. F. (2003) Phil. Trans. R. Soc. B458, 19-38
Inter-membrane space
I
II
III
IV
ATPase
Mitochondrial matrix
Protein subunit encoded in mitochondrial DNA
Protein subunit encoded in nuclear DNA
Mitochondrial inner membrane
H+
Direction of vectorial proton translocation
Direction of electron transfer
Inter-membrane space
I
II
H+
III
IV
H+
ATPase
H+
H+
NADH
O2
NAD+
succinate fumarate
H2O
ADP
ATP
Mitochondrial matrix
The mitochondrial theory of ageing
"Errors" in electron transfer - transfers to the "wrong"
electron acceptor - occur at fixed frequency.
The products of these reactions damage mitochondrial
genes, which then produce defective proteins, which
then make more "errors" in electron transfer....damaging
more genes, making more defective proteins....and so
on.
Coda. Two views of mitochondria
View 1
John Burn (Newcastle Institute of Clinical Genetics). Quoted in
The Times, 9th September 2005
Mitochondria:
– “…are not part of the genetic material that we consider
makes us as human beings.”
“My belief is that what we are doing is changing a battery that
doesn’t work for one that does….Changing the mitochondria
won’t affect the important DNA.”
Coda. Two views of mitochondria
View 2
Nick Lane. Power, Sex, Suicide. Mitochondria and the
Meaning of Life. Oxford University Press. Publication: 27th
October 2005.
Mitochondria:
– “…give striking new insights into why we are here at all,
whether we are alone in the universe, why we have our sense
of individuality, why we should make love, where we trace our
ancestral roots, why we must age and die––in short, into the
meaning of life.”