cell biology

2. Oxidative
phosphorylation
 ATP synthesis
 oxygen-consuming respiratory
chain
Deficiency
any symptom
any organ
any age

3. Mitochondrial
OXPHOS
deficiencies
Metabolic disorders
estimated at 1/8500 birth
genetic diseases
defects in mitochondrial or
nuclear DNA

4. mitochondrial
respiratory
chain
100 different proteins
13-encoded by mitochondrial genes
others by nuclear genes
3% of all the cellular proteins

5. mitochondrial
DNA
16,569 base pair
double stranded
circular molecule
lacks introns
D-loop
contains the
promoters for

6. independent
replication
transcriptio
n
translation
Mitotic segregation
Randomly
partitioned
Homoplasmy
All mtDNA
molecules are
identical
Genotypic drift
 Heteroplasmy
Any mutant
mtDNA
molecule

7.  mitochondrial proteins
 encode subunits of the
RC
 assembly of the
OXPHOS complexes
 synthesis of cofactors

8. Mitochondrial
Protein
Synthesis
 mammalian
apparatus is not
completely known
 resembles its
prokaryotic
counterpart
 different from the

9. differences from the universal code
AUA
codes
for
methio
nine
and
not
for
isoleuc
ine
UAG is used as a stop
codon
UGA serves as codon for
tryptophan rather than a
mammalian mtDNA
contains only 22 tRNA
genes, sufficient to read
all codons with a
mechanism unique to
mitochondrial system

10. all hydrophobic proteins
in the inner mitochondrial membrane
Mitochondrial mRNA
translation
takes place in a
complex bound to the
inner membrane
LETM1
an inner membrane
protein,
serves as an anchor

11. Requires…
 about 150 different proteins are
involved
 in the translation of the 13 proteins
 encoded by the mitochondrial
…and several initiation,
elongation and
termination translation
factorsribosomal assembly proteins
aminoacyl-tRNA synthetases tRNA-modifying en
rRNA methylating enzymes
(TFB1M)
ribosomal proteins