Lecture 11.5.14-11.7.14 (Exam #4) Flashcards
Redox Reaction is also known as
oxidation reduction reactions
Redox Reactions
reactions that are concerned with the transfer of electrons between species
Oxidation (4)
loss electrons
loss hydride
loss of energy
exothermic
Reduction (4)
gain electrons
gain hydride
gain of energy
endothermic
Oxidation reactions are_______ while reduction reactions are ________
spontaneous; nonspontaneous
Acids_____protons. Acid______electrons.
donate/accept
Bases____protons.Bases____electrons.
accept/donate
What does SHE stand for?
Standard Hydrogen Electrode
What is the purpose of SHE?
an electrode that is the basis for the thermodynamic scale of oxidation-reduction potentials
The abbreviation for SHE is
H+/H2
Examples of mobile carriers of electrons (2)
Cytochrome C; Q membrane
Examples of prosthetic groups (3)
FAD; heme; iron sulfur clusters
Example of redox couples
NADH/NAD+
Reduction potential
Eo
ability to reduce (how well one substance reduces another)
electrochemical concept
A + reduction potential is spontaneous or non-spontaneous?
spontaneous
What happens if electrons flow toward/away from SHE
towards from SHE= negative voltage (nonspontaneous)
away from SHE= positive voltage (spontaneous)
The reducing agent is ___
reductant that loses electrons and is oxidized
The oxidizing agent is_____
oxidant that gains electrons and is reduced
A - reduction potential has a ___affinity for electrons than SHE. It is an electron___.
lower;donor
reductant
Reductant
the donor of electrons than can reduce any compound with a less negative voltage
A + reduction potential has a ____affinity for electrons than SHE. It is an electron___.
higher; acceptor
oxidant
Oxidant
acceptor of electrons that can oxidize any compound with a less positive voltage
In the ETC, NADH ____ electrons eventually to____.
donates; O2
The inner membrane matrix is the______side of the mitochondria.
negative
The cytoplasmic membrane matrix is the____side of the mitochondria.
positive
NAD+ is coenzyme or prosthetic group.
coenzyme
FAD is a coenzyme or prosthetic group.
prosthetic group
delta E0
standard reduction potential difference between 2 half reactions
equation for delta E0 (measured in volts)
delta E0=E0 (acceptor/oxidant)-E0 (donor/reductant)
How do electrons flow in the ETC?
down their gradient
Electrons move from a carrier that is a ______towards carriers that are_____.
reductant(high r.p)/oxidants(low r.p)
How is the ETC a very efficient process?
Stepwise recovery of energy from oxidation of NADH and FADH2 during respiration to generate ATP
The ETC transfers electrons to different protein complexes, while ____ are pumped to make a gradient.
hydrogen ions
What are the complexes found in the ETC? (5)
NADH reductase (complex 1) Succinate Dehydrogenase (complex 2) Cytochrome-c oxidoreductase (complex 3) Cytochrome-c oxidase (complex 4) ATP Synthase (complex 5)
Mobile Carriers in the ETC
Ubiquinone (Q) & Cytochrome C
oxidative phosphorylation occurs where?
inner mitochondrial membrane
The driving force of oxidative phosphorylation is?
the electron transfer of NADH or FADH2 relative to that of O2
What happens due to the electron flow through the complexes?
Leads to the transport of protons across the inner mitochondrial membrane
How many ATPs per NADH
~3
How many ATPs per FADH2
~2
Q-Cycle
bring 2es to 1e transfer at a time
Order of electron transfer (7steps)
NADH-Complex 1- Q-Complex 3-Cytochrome C-Complex 4- O2
____is a mobile carrier of electrons to Complex 3
CoQ
Q pool
population of Q’s in the inner mitochondrial membrane
cytochrome (4)
any protein with an iron heme prosthetic group, can be Fe3 or Fe2
participate in one electron transfer
absorb light at different wavelengths
transfer only 1 electron at a time
Flavoproteins
proteins that contain either FAD or FMN as a prosthetic group
can participate in either 1 or 2 electron transport
Fe-S can only transfer ____ electrons and also involve ___ and ___. Why?
one; Fe2 and Fe3
Because of the close proximity of the iron atoms
Does Complex 2 transport protons?
NO
Which complexes transfer electrons to CoQ
Complex 1 & 2
Cells use ___ to break down glucose and store its energy in molecules of ATP
oxygen
When can the energy in glucose be used by the cells
once it is stored as ATP
The synthesis of ATP is coupled by?
oxidation of NADH and the reduction of O2
How is the positive free energy of ATP overcome?
the large negative free energy associated with proton flow down its gradient
Why can’t electrons be transferred directly from NADH to O2?
Because this allows the pumping of protons across the inner membrane that creates a gradient that eventually is responsible for the production of ATP
Electron Carriers of the ETC (5)
NADH-Q reductase Q cytochrome reductase cytochrome oxidase cytochrome c
Copper participates in ____ electron transfer
1
FMN is similiar to FAD except?
it lacks the adenine nucleotide
NADH is ______to NAD+
FAD is ______ to FADH2
oxidized; reduced
Complex 1 and Complex 2 are located on the ____side, while Complex 3 and Complex 4 are located on the ____ side
matrix; cytoplasmic
See Video about ETC
https://www.youtube.com/watch?v=xbJ0nbzt5Kw
During the electron transport there is _____ of electrons and ____ pumping of protons
spontaneous
nonspontaneous
Protons go back thru synthase____ while ATP is created ____
spontaneous
nonspontaneous
Fe3+ is the ___ form while Fe2+ is the ___ form.
oxidized; reduced
CoQ is hydrophobic or hydrophilic
hydrophobic in the the tails of the lipid bilayer
What are quinones?
compounds with a fully conjugated cyclic dione structure
How is QH2 produced?
The quinone ring of CoQ can be reduced to quinol in a 2e reaction
What is the prosthetic group of a cytochrome?
heme
Where all can CoQ accept electrons from?
Complex 1
Complex 2
G3P Dehydrogenase
Brief detail of Q cycle?
Q-(1e)->Q radical (semiquione radical)-(1e)->QH2
Complex 4 is the only component of the ETC that can
interact with oxygen due to copper
Oxygen is reduced to _____in complex 4, after the electrons are transfer from ____ to O2
water;cytochrome C
Although it happens one at a time, each electron in Complex 4 is passed due which order. What is being pumped?
cytochrome c->CuA->heme a->heme a3->CuB (STOPS)
protons
The O2 in complex 4 form what?
peroxide bridge between heme a3 and cuB
What are the 2 enzymes that are scavengers of radical oxygens?
superoxide dismutase
cataylase
What cleaves the peroxide bridge?
the addition of 2 more electrons and 2 more protons
Complex 1
transfers e’s from NADH to quinone pool and pumps H+
Complex 2
transfers e’s from succinate to quinone pool
Complex 3
transfers e’s from quinol to cytochrome c and pumps H+
Complex 4
accepts e’s from cytochrome c, reduces O2 to H2O and pumps H+
Complex 5
Harvests H+ gradient and regenerates ATP
Acid = more or less protons
MORE
gradient
difference in concentrations of molecules on either side of the membrane
electrochemical gradient
difference in protons and charges on each side of the membrane
____is the final electron acceptor, but then it is immediately _____to H2O
oxygen, reduced
ATP synthase makes ATP based off of what theory?
Chemiosmotic theory
What is the chemiosmotic theory?
the proton gradient is created by from the energy from electrons by pumping protons into the inner membrane space by complex 1,3,4
The process of osmosis is spontaneous or nonspontaneous?
nonspontaneous
How many hydrogen atoms have to flow through an ATP synthase to make ATP? What happens
3; There is a conformational change to produce ATP
Proton Motive Force
protons have a thermodynamic tendency to return to the matrix
Describe the experiment by Peter Mitchell (5)
- Complex 5 was placed in a membrane vesicle
- A known proton pump was placed in the vesicle (bacteriorhodopsin)
- Added ADP+Pi
- Shined UV light
- ATP produced
What are the domains of ATP Synthase and where are they located?
Fo: inner mitochondrial membrane
F1: protrudes from the inner mitochondrial membrane into the matrix
What is the function of Fo of ATP Synthase? Components?
Proton Translocation
C-C Ring
What is the function of F1 of ATP Synthase?Components?
ATP Synthesis and Hydrolysis
3 alternating alpha and beta subunits
What happens on the each subunits of the F1 region?
Alpha subunit: ADP can bind but no ATP made
Beta subunit: ATP is synthesized
The conformational change of ATP Synthase is in response to?
the gamma rotation
3 Steps of ATP Production
L:Loose (ADP+Pi bind)
T:Tight (ATP made)
O:Open (ATP released)
How big is each rotation?
120 degrees
What are the 2 ways to stop ATP Synthesis?
Uncoupler or a blocker
What is the mechanism of an uncoupler?
prevents H+ from pumping to make ATP synthase instead H+ get into matrix another way
Glyercol 3 PDH Shuttle
DHAP is reduced to G3P; NADH is oxidized to NAD+ [cytosol]
G3P-> DHAP; FAD is reduced to FADH2
Malate Aspartate Shuttle (more energy efficient)
Step 1: L-Asp ->oxaloacetate->malate [cytosol]
alpha ketoglumarate->glutamic acid
NADH->NAD+
Step2: malate->oxaloacetate->L-Asp [matrix]
NAD+-> NADH
glutamic acid->alpha ketoglumarate
What is a polymer of glucose?
glycogen
Where is glucose most predominantly stored as glycogen?
muscle and liver
Glucose stored in the liver/muscle is used for
bloodstream & glycolysis
What is the purpose of glycogen phosphorylase?
to the cleavage of phosphorolytic cleavage of alpha 1,4 glycosidic leakage of glycogen
one G1P is released
What serves as a prosthetic group for glycogen phosphorylase?
pyridoxal phosphate
What is the role of PLP (derivative of vitamin B6)?
acid base catalysis
NADH’s can not cross the mitochondrial membrane, so what mechanism is used?
Glycerol 3 Phosphate Shuttle
Malate Aspartate Shuttle
During Malate Aspartate Shuttle as glu goes in what comes out? As alpha keto goes out what comes in?
aspartic acid; malate
Enzyme: glycogen->G1P
glycogen phosphoylase
Enzyme: G1P->G6P
phosphoglucomutase
G6P can be transformed into what? (3)
G
PA
5-carbon sugar
What part does the glycogen phosphorylase attack?
non-reducing end “C-4 side”
What does PLP need?
5 glucose molecules
Local reciprocal regulation
concentration within the cell itself
Glycogen phosphorylase is _______
processive; it doesn’t dissociate and reassociate between each cut
Debranching enzymes
have 2 independent active sites, consisting of residues in dif segments of a single polypeptide chain
establish alpha 1,6 linkage
What are 2 debranching enzymes
transferase & glucosidase
G1P->_____->glycogen
What is the enzyme used?
glycogen synthase
When does regulation of glycogen phosphorylase work?
only when glycogen synthase does not
What are the 2 forms of phosphorylase? What position do they to be in?
A(R state:active) and B(T state:inactive)
What phosphorylase do muscle cells prefer? What puts this phosphorylase in the T and R?
B
AMP (put in R)
ATP and G6P (keep in T)
What phosphorylase do liver cells prefer?
A
Which phosphorylase has the phosphate?
A
Who puts the phosphate on phosphorylase?
glycogen phosphorylase kinase
Glycogenin
attaches glucose to Tyr to make a short polymer
What is a futile cycle?
if we break and make glycogen at the same time
What affects synthase activity?
ADP inhibits
G6P activates
Types of Synthase
A(active: R) & B (inactive:T)
What type of Synthase is found in muscles/liver?
muscles: A (make G)
liver: B (break G)
What triggers the removal of phosphate?
insulin
Hormones in the brain and pancreas?
brain: adrenaline (put Pi on)
pancreas: insulin (take Pi off) & glucagon (put Pi on)
How do hormones tell a cell what to do?
via signal transduction
Receptor
membrane bound protein that binds the ligand and causes signal
Ligand
molecule that binds the receptor
