2. Mitochondria
• 90% of ATP generated there
• 10 to 1000s per cell (highest in
brain, skeletal muscle, heart,
kidney, liver)
• About 50 known mutations of
human mitochondrial DNA
Chapter 12 (pp. 349-354)
3.
4. About 90 different proteins make up
the Electron Transport Chain
Figure 12.2
6. Mitochondrial DNA
…the “25th chromosome”?
16,568 bp
• 2 Ribosomal RNAs
• 22 Transfer RNAs
• 13 Proteins
2-10 copies
per organelle
Figure 12.3
7. • 13 of the 90 Electron Transport Chain proteins are encoded by mitochondrial
DNA.
• The other 77 (plus about 1000 other mitochondrial proteins) are encoded by
nuclear DNA.
...So, mitochondria truly are a cooperative venture between two genetic systems!
12. Homoplasmy =
Same mitochondrial genome in all tissues
of a body.
Heteroplasmy =
More than one mitochondrial genome
in a body, but can have various ratios
in different tissues.
13. Homoplasmy =
Same mitochondrial genome in all tissues
of a body.
Heteroplasmy =
More than one mitochondrial genome
in a body, but can have various ratios
in different tissues.
This one is more common !
14. If a mutation occurs in the mitochondrial DNA of the mother,
the severity of the disease in the offspring depends on:
• Amount of mutant mitochondria inherited by child
• Partitioning of mutant mitochondria to different tissues of
the body
• Energy needs of different tissues (higher in heart, muscle,
brain, liver)
15. Mitochondrial Encephalomyopathy with Lactic Acidosis &
Strokelike Episodes = ‘MELAS’ (pp. 355-357)
• Most common mitochondrial disease
• Recurrent strokes before age of 40
• Myopathy (muscle weakening)
• Lower pH (due to lactic acid build-up)
• Deafness
• Droopy eyelids
• Short stature
• Diabetes
16.
17. MELAS mutation is in the gene
for the tRNA for Leucine
80% of mutations
• reduced protein synthesis
• shorter tRNA half-life
• no new proteins
< See clumps of deformed
mitochondria in arteries
of brain….stroke?
18.
19. Kearns-Sayre Syndrome = KSS (pp. 358-359)
• Ophthalmoplegia (paralysis or weakness of one or more
eye muscles)
• Degeneration of pigment layer of retina
• Cardiac abnormalities
• Neurological abnormalities
• Onset at age 20 (fatal in few years)
• Large deletions (1000s bp) of mito DNA; duplications
• Is not typically inherited, but rather is ‘sporadic’ (meaning
it just seems to show up in people)
26. What can you do to prevent Free-Radical damage?
• Get your Vitamins-E and-C and β-Carotene (Vitamin-A precursor).
These are ‘anti-oxidants’.
• Regular exercise. Although exercise generates free-radicals
if you do it enough your body responds by absorbing them.
• Eat less. Lab rats on limited diets lived 50% longer, Fruitflies
lived 30% longer.
• Reduce smoking, drinking alcohol, fatty foods
• Get less sun exposure.
28. Mitochondria DNA can be used to study our past:
• Maternally inherited only
• No recombination
• Non-coding region collects mutations more
quickly than nuclear DNA (less of a repair mechanism)
Applications: Evolution & Forensics
31. DNA testing was done on the remains of a Vietnam
soldier who was buried in the Tomb of the Unknowns
at Arlington National Cemetery
Remains of unidentified soldiers from
WW I and WW II, Korea & Vietnam
32. In this case, they did RFLP analysis
of DNA from the mitochondria.
Extracted mito DNA from the
buried bones and compared
that to the DNA of the supposed
mother and siblings
33. It matched those of United States Air Force First Lieutenant
Michael Joseph Blassie. Lieutenant Blassie's remains were
returned to his family in July 1998, and were buried in his
hometown of St. Louis, Missouri.
Remains of unidentified soldiers from
WW I and WW II, Korea & Vietnam
