Topic 9 Flashcards
porins
proteins that form transmembrane channels permeable to molecules below 10kDA
cardiolipin
phospholipid with four fatty acyl tails synthesized within mitochondria that decrease permeability of mitochondria inner membrane to protons
cristae
folds of inner membrane; number varies with energy demands
95% of human mitochondrial proteins are encoded by…
nuclear DNA
T/F: Each mitochondria can contain diff. number of DNA molecules
T
mitochondrial fission requires
- dna replication
- rna synthesis
- membrane generation via phospholipid transfer from ER
- protein synthesis within mitochondria and protein importation from cytoplasm
Most nuclear encoded mitochondrial proteins are synthesized
on free ribosomes in cytoplasm
import of mitochondrial matrix and inner membrane proteins
with amino terminal presequence
Tom, Tim, Hsp70, MPP
target proteins to outer compartments
internal mitochondrial targeting sequence and internal compartment targeting sequences for intermembrane, outer, and some inner proteins
Tom complex
translocase of outer membrane
Tim complex
translocase of inner membrane
Hsp70
chaperones that keep proteins unfolded until reaching final destination
MPP
matrix processing peptidase that cleaves targeting sequence following transport
Tim9, Tim10
inter membrane space chaperones; carry protein to Tim 22 channel complex
Oxa-translocase
within inner membrane for proteins synthesized within matrix
Sorting of proteins containing internal targeting sequences to inner membrane
Tim9,Tim10, Oxa-translocase, inner membrane protein eroded by nuclear and mitochondrial DNA
Sorting of proteins containing internal targeting sequences to inter membrane space and outer membrane
Mim1, SAM, outer membrane with alpha-helix transmembrane and beta sheet/barrel transmembrane domains, inter membrane interacting with chaperones
Mim 1
inserts proteins with a single alpha helical transmembrane domain inserted into outer membrane
SAM
Sorting and Assembly Machinery for moving proteins from intermembrane to outer
cytoplasmic phospholipid transfer proteins
transfer phospholipids synthesized in ER to mitochondria
catabolism
breakdown of large, complex molecules into smaller, simpler molecules with release of chemical energy
ATP
captures energy released by catabolism to form phosphoanhydride bonds
hydrolysis phosphoanhydride bonds
provide energy for most cellular rxns
Two sources of Acetyl CoA
pyruvate and fatty acids
pyruvate
product of glucose breakdown through glycolysis
Citric Acid cycle produces ___ molecules of NADH and ___ of FADH2 that are used to make ATP through _____________________ via the electron transport chain
3, 1, oxidative phosphorylation
reduction of NAD+
accepts a proton and 2 electrons
oxidation of NADH
leases a proton and 2 electrons
During oxidative phosphorylation, electrons that enter the electron transport chain from NADH and FADH2 combine with ___ to produce _____.
O2, H2O
chemiosmotic coupling
electron transport through electron transport chain is coupled to ATP synthesis
chemiosmotic coupling involves storage of energy in a ____________ which is subsequently used to drive ATP synthesis
proton gradient
5 protein complexes of electron transport chain
DNA and mitochondrial encoded proteins
electron carriers
negatively charged molecules that can transfer a proton
coenzyme Q (ubiquinone)
lipid soluble electron carrier (e- carried to complex III)
cytochrome c (cyt c)
peripheral membrane protein on outer face of inner membrane (e- carried to complex IV)
Describe transport of electrons from NADH down electron transport chain within inner membrane
- e- enter ETC from NADH in complex I
- e- transferred to coenzyme Q to complex III
- e- transferred from cyt b to cyt c to complex IV
- complex IV transfers e- to oxygen
Describe transport of electrons from FADH2 down electron transport chain within inner membrane
- succinate produced in citric acid cycle is reduced by succinate dehydrogenase in complex II to generate FADH2
- FADH2 reduced to FAD +H2, donating e- to coenzyme Q
- e- transported through complex III and IV driving proton pump
complex I and III
transfer 4 protons per pair of e- per complex
complex IV
transfer of 2 protons per pair of e-, plus 2 protons combined with O2 to form water
electrochemical gradient
pH gradient and electric potential
proton motive force
deltaG of ~ -5kcal/mol per proton
phospholipid bilayer of the inner membrane is ___________ to ions so protons can cross only through….
impermeable, protein channels
complex V
ATP synthase; two subunits (F0, F1)
F0
spans inner membrane and forms channel through which protons move
F1
catalyzes synthesis of ATP (contains ATP synthase)
The flow of protons through ___ drives the rotation of part of ____ , which acts as a rotary motor to drive ATP synthesis.
F0, F1
___ protons are required to synthesize 1 ATP
4
oxidation of one NAHD yields __ ATP and oxidation of FADH2 yields __ ATP
3, 2
Transport of metabolites (ATP from matrix to cytosol, inorganic phosphate and pyruvate into matrix) across the mitochondrial inner membrane relies on…
electrochemical proton gradient
brown adipose tissue
predominant in hibernation gland and in newborn infants; higher levels of innervation, vascularization, lipid droplets, and mitochondria
thermogenin
uncoupling protein of inner mitochondrial membrane in brown adipose tissue; allows for transport of protons across inner membrane into matrix without going through complex V
cyanide
inhibits final e- transfer to oxygen driving all e- transfer to a halt
mitochondrial myopathic and neuropathies
-generally affect ETC and can arise through mutations in nuclear or mitochondrial DNA
chloroplasts
a plastid
peroxisomes
-single membrane organelles of eukaryotic cells
-can replicate but no genetic material
carry out metabolic functions, particularly oxidation rxns
-site of lipid synthesis
fatty acid oxidation in plants and yeast only occurs in ________ while FA oxidation in mammals also occurs in the mitochondria
peroxisomes
