Chapter 5 Flashcards
what other organelle is involved in the fission of mitchondria?
the ER. wraps around the mito and acts as a noose. fission facilitated by DRP1 proteins
T/F: mitochondria contain cholesterol
false, they contain cardiolipid, a disphophatidyl glycerol
role of cardiolipid
a di phosphatidyl glycerol that facilitates protein complexes involved in ETC and ATP synthesis
which of the two membranes in a mitochondria have more proteins
the inner mito membrane has more proteins
what enzymes are contained in the outer mito memberane
enzymes involved in trytophan synthesis and epinephrine oxidation and FA elongation
why is the outermembrane so permeable compared tot he inner membrane?
the outermembranes have porin channels that allow flow of ATP, NADH, coA etc
Where in the mito is the DNA and the ribosomes
in the matrix
why is mito DNA important
it codes for 2rRNAs and 22tRNAs responsible for mito protein synthesis
mitochondrial RNA is synthesized by ____ polymerase
RNA polymerase
3 steps of cell resp for aerobes
1) glycolysis
2) Krebs
3) ETC
2-carbon acetyl coA is ____ with oxaloacetate to form citrate
condensed
ketogenic amino acids
amino acids that are broken down into acetyl coA
glucogenic amino acids
AAs that are broken down into Krebs intermediates
what does the glycerol phosphate shuttle do
converts cytosolic NADH from glycolysis into the inner membrane by converting it into FADH2
two methods of cytosolic nadh entering the inner membrane to go through ETC
1) malate aspartate shuttle
2) glycerol phosphate shuttle
oxidative phosphorylation
when ATP formation is driven by energy that is released from electrons removed during substrate oxidation
good oxidizing agents have a ____ electron affinity
high electron affinity. oxidizing agents will oxidize a substance because it wants its electrons
redox reactions are accompanied by a ____ in free energy, why?
decreased in delta G. as electrons get passed, they lose energy, you cannot pass electrons to create a higher energy product spontaneously
electron carriers in the ETC complex I have a _____ redox potential than complex IV
complex I has a lower redox potential. Complexes are in order of increasing electron affinity (higher and higher electron affinities)
5 types of electron carriers
1) flavoproteins
2) cytochromes
3) Fe-S
4) Three Cu Atoms
5) ubiquinones
what is a flavoprotein and how many electrons can they accept? what vitamins are they derived from?
flavoprotein is an electron carrier that is a poly peptide bound to FMN or FAD. derived from B2. can accept 2 e-
Cytochromes contain a ____ prosthetic group. how many e- can they carry? how many types of cytochromes?
heme prosthetic group, can carry one e- (fe3+ to 2+), 3 types of cytochromes (a,b,c)
3 Cu atoms. How many electrons can they hold?
1 e=
Ubiquinone is ____ soluble. how many electrons does ubiquinone hold? What is it made of?
its lipid soluble, can hold 2 e-. Made of 5 isoprenoid rings
What are Fe-S electron carriers? how many e- can theyhold?
Fe-s is an electron carrier with iron covalently bonded to inorganic sulfer. can hold one e-.
how are Fe-S electron carriers linked to their specific protein complexes?
through cystein residues
how is the sequence of Fe-S electron carriers in the ETC determind
using inhibitors
example of an FMN flavoprotein
Quinone–>semiquinone—>hydroquinone
redox states of ubiquinone
ubiquinone —>ubisemiquinone —> ubiquinol
alternative name for complex I
NADH dehydrogenase
name for complex III
cyt c reductase
name for complex IV
cyt c oxidase
why are complexes called proton pumps?
because it uses active transport in the form of electrons to pump protons across the gradient
how does cyt c oxidase (complex IV) pump protons across the gradient?
it relies on the energy released by oxygen reduction to drive conformational change of the pump to push protons across
what are substrate protons?
protons that get used by complex IV but do not get pumped across the gradient. these protons are consumed in complex IV’s reactions.
complex 4 uses 8 protons in total:
- 4 as substrate protons
- 4 that are pumped across the membrane
both types contribute to creating an electrochemical gradient
2 components to the proton gradient. What do these components create?
1) the concentration gradient, creating a change in pH
2) the separation of charge across the membrane creates an electric potential
both components create the proton motive force
chemiosmotic theory
generation of ATP via ATP synthase, which functions by coupling H+ flow/translocation that is powered by e- transfer down the electron transport chain
how does DNP uncouple glucose oxidation with ADP phosphorylation?
it is lipid solluble and engulfs a proton, allowing protons to move back into the cell through its gradient. No atp is formed during this.
how does rotenone block electron transport?
it keeps Fe-S electron carrier in complex I reduced, so no electrons can be transfered to ubiquinone.
how does antimycin A block electron transport
inhibits the oxidation of ubiquinone. electrons cannot be transfered to complex III
Why is cyanide lethal?
because it blocks the ETC, block complex IV at the site where O2 is supposed to accept e-
how can you remove the F1 particles of ATP synthase for analysis?
1) sonification to expose ATP synthase heads
2) treat with Urea
bindning change mechanism
energy released by movement of protons does not direcly drive ADP phosphorylation, but CHANGES THE BINDING affinity of the active site for ATP production
how many active sites on F1
three, the beta subunits)
three statees of F1beta subunts
1) L state; loose state, reactants loosely held
2) tense state: reactants are smooshed together (forms atP)
3) open state: low affinity for nucleotides, ATP is released.
ATP is synthesized by _____ catalysis
rotational catalysis: stalk rotates relative to the alpha and beta subunits in the F1 head
the pmf and electrical energy stored in the proton gradient is ______ into mechanical energy (rotation of F0 base and stalk), which makes ATP
transduced
___ degree rotation creates one atp
120 degree rotation of the stalk creates one atp
how can you directly observe rotational catalysis?
by tagging the gamma subunit (stalk) with a fluorecent actin filament. attach the filament by switching a serine residue to a cysteine of the stalk
what amino acid in Fo complex is required for the protons to enter the c subunit disk?
Asp61 is present in the C subunit, binding the protons. everytime a proton binds, the ring rotates 30 degrees
for every ATP produced, how many H+ ions need to be moved?
4 get pumped back into the matrix
function of adenine nucleotide translocase
transport ATP from matrix to the cytosol for cellular activities, exchanging for ADP
functino of peroxisomes
site of H2O2 synthesis and degradation
