Mitochondria Flashcards Preview

Biochemistry MBS > Mitochondria > Flashcards

Flashcards in Mitochondria Deck (28):
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

mitochondrial permeability transition

-loss of the impermeability of inner mitochondrial membrane
-caused by the permanent opening of the ANT pore caused by eg excess of calcium
-triggered through calcium dependent binding of matrix protein cyclophilin D to ANT
-can be inhibited by a non-specific CypD inhibitor (cyclosporine A)
-MPT happens in the cardia and neuronal cells during times of ischemia
-MPT causes collapse of the mitochondrial membrane potential (stopping ATP synthesis), destruction of the mitochondrial outer membrane and release of pro-apoptotic molecule from the intermembrane space