Flashcards in Mitochondria Deck (28)
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1
4 compartments
-outer membrane
-inner membrane
-intermembrane space
-matrix
2
outer membrane
-permeable to molecules up to 10 kDa
3
inner membrane
-impermeable
-molecules need a specific transporter/shuttle to pass through
-oxidative phosph proteins are located here
4
matrix
-contains TCA cycle enzymes and mitochondrial DNA
5
mtDNA
-size
-copies
-encodes
-different from genomic DNA
-small, circular (17kb)
-up to 10,000 copies per cell
-encodes 13 oxphos proteins, 2rRNAs and 22tRNAs
6
majority of mitochondrial proteins are...
-encoded for in genomic DNA
-synthesized in the cytosol
-have to be transported into the mitochondria
7
mitochondrial import of proteins is carried out by
-TOM (outer membrane)
-TIM (inner membrane)
8
targetting region of mitochondrial proteins
-typically N-terminal
9
energy requirement of proteins getting into the mitochondria
-energy dependent process
-proteins must be unfolded upon entry and refolded once inside
10
TOM proteins
transport proteins from the cytoplasm through the outer membrane
-TOM70: transports proteins that are destined to be integral membrane proteins in the inner membrane of the mitochondria
-TOM20: transports proteins that are destined to reside in the matrix
-TOM40: this is the actual channel protein which the mitochdria bound proteins pass through (lives in the outer membrane)
11
TIM proteins
-responsible for getting mitochondrial proteins through the inner membrane
12
Step 1 of oxidative phos
-called the respiratory chain
-a series of redox couples that transfer electrons from donors (NADH, succinate) to the final acceptor, oxygen
13
step 2
-transfer of protons from the matrix into the intermembrane space, creating a membrane potential between matrix and intermem space.
-this is called a proton gradient
-this is done via energy created from the respiratory chain
14
what complexes push electrons into intermembrane space
1,3,4
15
step 3
-F0F1 ATP synthase (complex 5) uses proton motive force to synthesize ATP from ADP and Pi
-
16
F0 complex
-part of complex 5 of oxphos
-proton channel in the mitochondrial inner membrane
17
F1 complex
-contains 3 ATP synthesizing active centers (faces mitochondrial matrix)
18
mechanics of F0F1 ATP synthesis
-F0 lets in protons creating a mechanical force that produces a confirmational change in active centers on F1
-these confirmational changes promote ATP synthesis
19
oligomycin
-inhibitor of ATP synthase
20
coupling
-interdependence of the rates of the respiratory chain (e transfer/oxygen consumption) and the rate of ATP synthesis
-this means that if one is inhibitted, it will directly inhibit the other
21
two main factors in the rate of ATP synthesis
-availibility of substrates of complexes 1 and 2 (NADH and succinate) (uncommon)
-availability of ADP for ATP synthase (very frequent)
22
uncoupling
-loss of coupling between respiratory chain and ATP synthase
-happens if protons are allowed back into the matrix without going through ATP synthase (through a different proton channel)
-membrane potential is abolished, respiratory chain is working at full steam, and ATP synthase isnt generating any ATP
-this will produce heat instead of ATP
23
how to test coupling
treat cells/mitochondria with oligomycin and measure oxygen consumption
-if it is decreased then mitochondria is coupled
24
uncouplers
-FCCP, dinitrophenols, UCP1/thermogenin
-brown fat contains mitochondria and burns calories at maximal rates
25
uncoupled mitochondria and obesity
-uncoupling forces respiratory chain to burn calories at a maximal rate without doing work
-this could be useful against obesity, however, heat production could be a harmful side affect
26
ANT
-adenine nucleotide translocase
-transports newly synthesized ATP from the mitochondrial matrix into the cytosol and ADP from cytosol into the mitochondrial matrix
27
inhibitors of ANT
-altractyloside
-bongkrekic acid
28
