Mitochondria & Peroxisomes Flashcards
what does the number of mitochondria on the cell depend on?
the metabolic requirements of the cell
how is mitochondria different to other organelles?
they contain their own circular DNA
explain endosymbiosis in terms of mitochondria
- small free living prokaryotes were engulfed but not consumed by larger eukaryotes and the two developed a symbiotic relationship.
- smaller organism provides ATP and the larger one provides nutrients
where are mitochondrial proteins made?
in their own ribosomes
how are mitochondria organised in skin fibroblast cells?
mitochondria interconnected to form networks
how are mitochondria organised in cardiac cells?
they are in abundance and reside in distinct zones
how are mitochondria transported?
they are transported on microtubules by dynein and kinesin
what are the functions of mitochondria?
- fatty acids are broken down to acetyl CoA
- decarboxylation of pyruvate to acetyl CoA
- breaks down acetyl CoA
- oxidative phosphorylation
- thermogenesis to generate heat
- apoptosis
what is abnormal in patients with beri beri?
higher than normal serum levels of pyruvate and ketogluarate (alpha)
what is the function of peroxisomes?
production of cholesterol and phospholipids
- contain enzymes that use oxygen to oxidize substrates
- produce hydrogen peroxide
- important in breaking down long chain fatty acids
- steps in synthesis of certain lipids
- breakdown of excess purines to uric acid
what targets peroxisomal proteins to the peroxisomes?
PTS (peroxisome targeting signal)
what are some symptoms of beri beri?
- damage to the peripheral nervous system
- pain in the limbs
- weakness of the musculature
- distorted skin sensation
- the heart may be enlarged and cardiac output inadequate
describe the structure of peroxisomes
- approximately 0.1-1 μm in diameter.
- surrounded by a single lipid bilayer membrane.
- no DNA or ribosomes (meaning they do not make the proteins that they contain, they instead acquire them).
