Mitochondrial Oxidative
Phosphorilation and
Genetics
Abigail Hardy
The Mitochondria
Thousands of
mitochondria in
high energy areas
 Contact sites
facilitate the entry
of protiens into
matrix
 Produces ~90% of
the cellular ATP in
eukaryotic cells

Major Protien Complexes
Oxidative Phosphorylation


Complexes I to IV, in
addition to other
components, act together
as an electron transport
chain
Protons in intermembrane
space form an
electrochemical gradient,
which provides potential
energy used by complex
V for the phosphorylation
of ADP to ATP.

Membrane channel
protien (ANT) transports
ATP out and ADP into
matrix
– 1:1 ratio of transfer

Both ADP and ATP move
freely through the outer
membrane
Mitochondrial DNA
Mitochondria have
their own genetic
apparatus
 Circular (16,568 bp)
 2-10 separate
mitochondrial
gemomes in matrix
 Carries information
for:

– 2 rRNAs
– 22 tRNAs
– 13 proteins
The 13 proteins
encoded are involved
in OXPHOS functions
 Nuclear genes encode
about 70 additional
protiens that make up
the OXPHOS system
 A mitochondrion is
the joint product of
two different genetic
systems

Human Mitochondrial Genome
Mitochondrial Replication
During mitochondrial multiplication each
genome is randomly distributed to a
daughter mitochondrion
 Does NOT follow the Mendelian pattern of
inheritance b/c not part of chromosomal
system
 Details of mitochondrial reproduction are
not known

Mitochondrial Genetics


Mitochondria of
the zygote come
from the oocyte
(mother) and
almost never the
sperm (father)
If the same set of symptoms in a number of various
multigenerational families is inherited only from affected
females and almost never from affected males, then
there is a strong likelihood that it is caused by a
mutation in one of the mitochondrial DNA genes
Oocyte Mitochondria
Human oocyte loses
mitochondria as it
matures through the
genetic bottleneck
 Mitochondria are
randomly distributed into
daughter cells
 Mitochondrial
Mutation Load= the
ratio of mutated to
normal mitochondrial
DNA

Homoplasmy= all
mitochondria of a cell or
tissue have the same
genome
 Heteroplasmy= contains
both mutant and wildtype genomes

– Proportion of mutant to
wild-type M. DNA
determines if energy
shortage occurs

Threshold for phenotypic
expression
Bibliography

Widmaier, E.P., Raff, H., Strang, K.T. Vander’s Human
Physiology: The Mechanisms of Body Function. 10th ed.
Boston: McGraw-Hill, 2005.

www.cbs.dtu.dk/staff/ dave/roanoke/bio101ch06.htm