Block 1 Lecture 9 Flashcards
(23 cards)
what is homeostasis in cells
their fabric is continually replaced but the overall structure in unchanging
what is fission
when mitochondria split in 2
how can mitochondria synthesize new proteins
mtDNA
what is autophagy
process where worn out mitochondria are broken down
what breaks down mitochondria
lysosomes
what is the mechanism of autophagy
ER wraps around mitochondria, hydrolytic enzymes are introduced by fusion with lysosomal vesicle, the inside becomes acidic and mitochondria are digested
what do mitochondria have their own of
DNA, ribosomes, tRNA
where is DNA found in mitochondria
in the matrix in nucleoids
what do nucleoids contain
4-5 copies of mtDNA
where do most proteins in mitochondria come from
most are synthesized in cytosol and transported into mitochondrion
what are TOMs
translocon of outer membrane
what are TIMs
translocon of inner membrane
how do proteins enter the mitochondria
- signal sequence happens at recognition
- inserted into membrane by TOM complex
- translocated into matrix
- cleavage by signal peptidase
why is mtDNA maternal
because sperm cell has 100 mitochondria and oocyte has 100,000
what is heteroplasmy
where a cell or tissue contains more than one type of mitochondrial genome
what are the roles of mitochondria
- apoptosis
- heat production
- generation of reactive oxygen species
- calcium store
- role in some diseases
what is the mechanism of apoptosis
- opening of the permeability transition pore lets cytochrome C exit
- cytochrome c activates apaf 1
- apaf 1 activates caspases
- intracellular proteases degrade cellular components
what is the role of mitochondria in pancreatic B cells
serves as fuel sensors that link glucose exposure to insulin release
what is the mechanism of mitchondrias effects in a pancreatic b cell
- GLUT2 transporters introduce glucose and mitochondria cause increase of ATP:ADP ratio
- K+ gate closure causes depolarization
- voltage sensitive Ca2+ channels open
- exocytosis of insulin granules to bloodstream
what are uncoupling proteins
transmembrane proteins that decrease the proton gradient generated in oxidative phosphorylation
what does uncoupling protein 1 do
- diverts energy from ATP generation to adoptive thermogenesis (Heat release)
- thermogeneic uncoupling occurs in response to overeating and cold
- decrease in mitochondrial production of damaging ROS
what does uncoupling protein 2 do
- plays role inn metabolic adaptation to fasting regardless of weight
- cuases nonthermogenic uncoupling
- negative regulation of insulin secretion in pancreatic beta cell contributing significantly to type 2 diabetes induced by superoxide generation
how is the 3 person baby made
female with mutant mitochondria has mitochondria discarded. her nuclear genome is fused with healthy mitochondria from another female to make an oocyte. a Male sperm fertilizes with the oocyte.
