Mitochondria

Question 1

What is function of mito

Answer 1

ATP production and apoptosis

Question 2

Describe mitochondria shape and distribution

Answer 2

Lamellar cristea - most common: Hepatocyte (oval with num cristea) Skeletal (In rows btwn myofibrils) Sperm (wrapped around flagella)
Tubular Cristea - steroid secreting cells

Question 3

What is general structure of mitochondria

Answer 3

OM - Intermemb space - IM - matrix

Question 4

Describe the outer membrane of mt

Answer 4

Permeable to small molecules = porins

Biochem rxn: Cardiolipin synth and lipid mod

Question 5

Describe the inner membrane of mt

Answer 5

Impermeable to most molecules (Cardiolipin)
Cristea increase SA, incs ETC and ATP synthase, important receptors for matrix proteins
20% = CL = 2xPL=4 tails = impermeable

Question 6

Describe the matrix of mt

Answer 6

mtDNA, mtRibo, tRNA, rRNA present

Location of oxidative metabolism (pyruvate oxidation, FA oxidation, TCA)

Question 7

What is the pathway for energy Generation

Answer 7

Glycolysis in cyto - pyruvate + FA - mt - Acetyl coa - meta by TCA (Nad+ to nadh) - high energy electrons from nadh passes along ETC to O2 - creates proton gradient across IM - drives ATP synthase - mechanical potential drives adp to atp

Question 8

Describe ATP synthase

Answer 8

Head= ATPase; subunits bind adp and Pi

Question 9

Describe thermogenesis function

Answer 9

Uncoupling protein (UCP) = Thermogenin (in IM channel) allows protons to leak from cyto to matrix therefore decoupling ATP synthase from respiration resulting in oxidative metabolism (TCA and ETC) producing heat (Brown adipose)

Question 10

Describe Reactive Oxidative species (ROS)

Answer 10

Ox-phos in mt generates energy and ROS which can inactivate ETC electron accpetors therefore increasing number of ROS.
ROS dmgs proteins, rna, dna (mtDNA more suc as no histone and decreased dna repair) (linked with alz, cancer, and aging)

Question 11

What are some antioxidants to deactivate ROS

Answer 11

glutathione, peroxidase, super oxide dismatase

Question 12

Describe apoptotic role of mt

Answer 12

Preapoptotic bcl-2 proteins (BAD + BAX) translocate from cyto to mito membrane in response to cell dmg and stress -> Forms pores in OM -> Release of pro-apoptotic factors in cytosol (cytochrome C) -> activates capase cascade -> apoptosis

Question 13

Describe mt inheritence

Answer 13

Bottleneck (only % of mtDNA given) leads to variability in disease = heteroplasmy

Question 14

Protein import and role for mt

Answer 14

mt not self sufficient
transL in cyto - Hsp 70 (stops fold) - mt via sig seq - TOM (OM recog sig) - TIM (transloc via e-chem gradient to IM) - sig seq removed via matrix protease - spont fold or Hsp60 and ATP

Question 15

Describe Bath Syndrome

Answer 15

X-linked cardiolipid synth disorder = cardiomyopathy, muscle weakness, neutropenia, sudden death infants