Mitochondria LECTURES
overview
A. Mitochondria LECTURES overview
Mitochondrial
Structure
The arrangement of membranes:
distinct inner and outer membranes, The location of ATPase, DNA and ribosomes
Fatty
Acid Oxidation
B.Ê THERMINOLOGY
Ê
Chemiosmosis - the production of ATP by coupling the transfer of H+
across a membrane, down their concentration to the phosphorylation
of ADP.
Mitochondrial Structure öÊ
(a) Cristae ÷ the folds of the inner mitochondrial
membrane. (b) Matrix
÷ the space in the mitochrondria internal to the cristae.
Oxidation - loss of electrons from
a substance involved in a redox reaction.
Oxidative phosphorylation - the production of ATP making use of the proton
motive force across the inner mitochondrial membrane.
Proton-motive
force - the potential energy contained
in the electrochemical gradient produced by the vectoral
transport of protons across biological membranes.
Reducing agent ÷ a molecule that
transfers electrons to reduce another molecule.
Reduction - the gain of electrons
by a substance involved in a redox reaction.
Substrate-level
phosphorylation
- when ATP is made by transferring a phosphate group
from another molecule to ADP
ATP is the most readily
accessible chemical energy store for use in metabolic reactions; ATP is a high energy molecule because the bonds between the three
phosphate groups are unstable, and release a lot of energy when broken; ATP
provides energy to a reaction by transferring a phosphate to an intermediate
and increasing its energy level.
Glycolysis is the conversion of glucose to pyruvate
(plus 2ATP plus 2NADH) in the cytosol of a cell.
NAD+ accepts a pair of
electrons to become NADH. NADH is a reducing agent in
many reactions.
The Krebs cycle occurs in
the matrix of the mitochrondria;The first step of the
Krebs cycle adds two carbons from acetyl CoA to oxaloacetate (4C) to make citrate (6C). As
the cycle is completed, oxaloacetate is regenerated, 1 ATP, 3 NADH and 1 FADH2 are produced, and two CO2 released
per pyruvate molecule.
The electrons from the NADH
and FADH2 produced in glycolysis and the Krebs cycle
are passed through the electron transport chain in the inner mitochondrial membrane. The vast
majority of the ATP produced indirectly, as a result
of the electron transport chain.
The electrons are passed to a series of carriers, each one more
electronegative than the next.
O2 is the most
electronegative, and is the final electron acceptor in the mitochrondrial
ETC.
The electrochemical gradient
contains potential energy, which is used by ATP synthase to phosphorylate ADP as
protons are allowed to move from the intermembrane
space to the matrix.
C.ÊÊÊÊÊÊÊ questions
1. Anoxic glycolysis results in the formation of how many moles of
ATP from ADP and Pi (per mole of glucose)
a)
1
b)
2
c)
6
d)
36
e)
38
2. Glycolysis leads to the production of ____________ and two
molecules of ATP. In the absence of oxygen,
fermentation leads to the production of ______________. Glycolysis plus the citric acid cycle can convert the
carbons of glucose to _________ , storing the energy
as ATP, _____________ and ___________.
a.
lactic acid, pyruvate,
CO2, NAHD, FADH2
b.
pyruvate, lactic
acid, CO2, NADH, FADH2
c.
CO2, lactic acid, pyruvate,
FADH2
d.
O2, lactic acid, pyruvate,
FADH2
e.
glucose, lactic acid, CO2, FADH2
3. At the
end of glycolysis, each molecule of glucose has
yielded 2 molecules of _______, 2 molecules of
________, and a net of 2 molecules of _________.
a.
FAD, NAD+, ATP
b.
CO2, NAD+, ADP
c.
Lactic acid, ethanol, CO2
d.
pyruvate, NADH,
ATP
e.
H2O, CO2, ATP
4. In the
absence of oxygen, the primary purpose of fermentation is to:
a.
produce amino acids for protein synthesis
b.
generate a proton gradient for ATP synthesis
c.
oxidize glucose to generate reduce electron
carriers
d.
generate alcohol for beverages
e.
regenerate NAD+ from NADH allowing glycolysis to continue
5. The
inside part (analogues to the cytosol of a bacterium)
of a mitochondrion is called:
a)
cytosol
b)
stroma
c)
intermembrane space
d)
matrix
e)
periplasm
6. Porins may be found:
a)
in the outer membrane of gram-negative bacteria
b)
in the outer membrane of chloroplasts
c)
in the outer membrane of mitochondria
d)
in the inner membrane of mitochondria
e)
in a), b) and c) but not d)
7. The
terminal electron acceptor during mitochondrial
respiration:
a.
H2O
b.
NAD+
c.
FAD
d.
ATP
e.
O2
8. During
TCA cycle, the conversion of succinate to fumarate
a)
in oxidation that passed electrons fo FAD to make FADH2
b)
is a reduction that passes electrons to FAD
c)
is a reduction that passes electrons to NAD+
d)
ia a isomerization
e)
none of the above
9. The
major production of ATP during aerobic metabolism occurs when electrons from
__________ and _____________ are transferred to
_______________.
a.
FADH2, NADH, H20
b.
O2, FADH2, NADH
c.
FADH2, O2, NADH
d.
NADH, O2, FADH2
e.
FADH2, NADH, O2
10. Glyoxylate shunt
a)
provide extra electrons to make ATP
b)
produce additional intermediates in the TCA cycle
c)
prepare precursosrs for
FA synthesis
d)
prepare glucose for fermentation
e)
provide signal to neighboring cells
11. In the
presence of an uncoupler, one may expect:
a)
rate of electron transport to decrease
b)
rate of electron transport to increase
c)
ATP synthesis to stop
d)
Both a and c
e)
Both b and c
12. Which
of the following statements about mitochondria is false? Ê
a.
They contain an inner and an outer membrane.
b.
The region enclosed by the inner membrane is termed
the matrix.Ê
c.
They contain DNA and ribosomes.Ê
d.
They are an important site for energy production in
cells.Ê
e.
They contain stacked internal thylakoid
membranes.
13. If you
isolate mitochondria and place them in buffer with a low pH they begin to
manufacture ATP. Why?
a.
Low pH increases the concentration of base causing
mitochondria to pump out H+ to the inter membrane space leading to ATP
production.
b.
The high external acid concentration causes an
increase in H+ in the inter membrane space leading to increased ATP production
by ATP synthetase.
c.
Low pH increases the acid concentration in the mitochondrial matrix, a condition that normally causes ATP
production.
d.
Low pH increases the
14. In eukaryotic cells during aerobic respiration, most ATP
synthesis occurs associated with
a)
at the cellâs unit membrane
b)
at the endoplasmic reticulum
c)
at the mitochondrial
outer membrane
d)
in the folds of the mitochondrial
inner membrane
e)
in the thylakoids of the
mitochondrion
15. The
electron transport chain is located predominantly in the:
a.
Outer membrane of the mitochondria.
b.
Intermembrane space of the mitochondria.
c.
Inner membrane of the mitochondria
d.
Matrix of the mitochondria
e.
Cytoplasm of the cell
16. What
cellular compartment becomes acidic (high concentration of hydrogen ions)
during mitochondrial electron transport? Ê
a.
Mitochondrial stroma
b.
Cytoplasm.
c.
Endoplasmic reticulum.
d.
Space between inner and outer mitochondrial
membranes
e.
Thylakoid membranes
17. ATP synthase can produce ATP using as a
direct energy source:
a)
energy from the conversion of glucose to pyruvate. Ê
b)
energy from the oxidation of pyruvate
producing CO2 and H20
c)
energy from a proton gradient established in
mitochondria
d)
energy derived from the breakdown of NADH and FADH2
e)
energy from the metabolism of amino acids
18. In the
F-type ATP-ase, the catalyc
site(s) at which ATP binds is:
a)
in the Fo portion
b)
in the F1 portion
c)
in the F3 portion
d)
in the F3 portion
e)
none of the above
19. Synthesis
of one ATP by the F-type ATPase is
accomplished by:
a)
the complete rotation of the gamma subunit
b)
120 degree of rotation of the gamma subunit
c)
180 degree of rotation of the gamma subunit
d)
substrate-level phosporylation
e)
none of the above
20. ATP is synthesized in the F-type ATPase
when the binding site is in:
a)
homeostasis
b)
the F configuration
c)
the T configuration
d)
the O configuration
21. Which
of the following activities in mitochondria require proton-motive force?
a)
ATP synthesis
b)
Phosphate transport
c)
ATP transport
d)
ADP transport
e)
all of the above
Correct Answers:ÊÊÊÊ 1b,
2b, 3d, 4e, 5d, 6e, 7e, 8a, 9e, 10b, 11e, 12e, 13b, 14d, 15c, 16d, 17c, 18b,
19b, 20, 21e
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