Mitochondria and chloroplasts SBS922 Membrane Biochemistry 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 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 3 rd year course Membrane Proteins. Chapter 4 is good for Membrane Biochemistry lectures and practicals

– 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? Mitochondria (singular; mitochondrion).

Scientific Art From Lane, N. (2005) Power, Sex, Suicide: Mitochondria and the Meaning of Life

Mighty Mitochondria copyright Odra Noel

A mitochondrion—one of many tiny power- houses 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

IIIIIIIVATPase Mitochondrial matrix Inter-membrane space

Protein subunit encoded in mitochondrial DNA Protein subunit encoded in nuclear DNA Direction of vectorial proton translocation H+H+ Direction of electron transfer Mitochondrial inner membrane

IIIIIIIVATPase Mitochondrial matrix Inter-membrane space H+H+ H+H+ H+H+ H+H+ NADHO2O2 ATP ADP H2OH2O NAD + succinatefumarate

"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. The mitochondrial theory of ageing

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 1

Nick Lane. Power, Sex, Suicide. Mitochondria and the Meaning of Life. Oxford University Press. Publication: 27th October 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.” Coda. Two views of mitochondria View 2