Bios 3200 Exam 2

where is the majority (~80%) of ATP produced?

mitochondria

what are the two membranes of the mitochondria?

inner and outer membranes

what are the two spaces of the mitochondria?

matrix and intermembrane space

the inner membrane of the mitochondria has a __________ _________ system to make H+ gradient

electron transport

the inner membrane is full of ______, but it is not _____

proteins, rigid

the mitochondria is flexible, and it is continuously _________, _____________, and __________

moving, dividing, fusing

why are cristae formed?

inner membrane of mitochondria needs a large surface area

what does the mitochondrial matrix contain enzymes for?

citric acid cycle

what does the mitochondrial outer membrane contain?

porin - free pass for small molecules (<1000 daltons)

where does glycolysis occur?

cytosol

in glycolysis, what are the net products for 1 molecule of glucose?

2 pyruvate, 2 ATP, 2 NADH

what forms acetyl-CoA?

when the acetyl group of pyruvate is transferred to CoA (coenzyme A)

the citric acid cycle oxidizes all carbon to _____

CO2

what are the products made after glycolysis/citric acid cycle per 1 pyruvate?

4 NADH, 1 FADH2, 1 GTP (= 1 ATP), 3 CO2

where does the citric acid cycle occur?

mitochondrial matrix

NAD

nicotinamide adenine dinucleotide

NAD+

oxidized form, nicotinamide ring has 1 H and positive charge on nitrogen

NADH

reduced form (high energy state), nicotinamide ring has 2 H and no charge on nitrogen

what is redox potential?

how energetically favorable it is to reduce (give electron to) other chemicals; strength as an electron donor

what is the mechanism/order of operations for the electron transport chain (complexes I-IV)?

1. electron pairs from NADH are received at complex I and are then transferred to ubiquinone (Co-Q)

2. electron pairs from FADH2 are received at complex II and are then transferred to Co-Q

3. Co-Q carriers the electrons to complex III, which then transfers the electrons to cytochrome C

4. cytochrome C carries the electron pairs to complex IV where they reduce O2 and produce H2O

which complexes are H+ pumped out of into the intermembrane space?

complexes I, III, IV

how many H+ does complex I pump out?

4

how many H+ does complex III pump out?

4

how many H+ does complex IV pump out?

4

what are the 2 electron carriers in the ETC?

ubiquinone (Co-Q) and cytochrome C

ubiquinone (Co-Q)

permanently embedded in inner membrane; can receive two electrons with two protons

what does the reduced form of ubiquinone look like?

has 2 OH groups opposite of each other (high energy)

what does the oxidized form of ubiquinone look like?

has 2 double bonded O opposite of each other (low energy)

what is the chemiosmatic theory?

free energy is created by H+ electrochemical gradient

energy can be used for ATP generation

not metabolic ATP synthesis; closed membrane is essential for the reaction, pH change affects ATP synthesis by isolated mitochondria

what are the other 2 names for F₁F₀ ATPase?

ATP synthase, complex V

what does ATP synthase do? (basic)

convert electrochemical gradient of H+ into ATP; final step of ATP synthesis

what are the two main parts of ATP synthase?

F₁ and F₀

what is F₀?

transmembrane H+ carrier

what is the structure of F₀?

12 c-subunits, form c-ring

1 a-subunit

2 b-subunits

what is F₁?

catalytic component of ATP synthase

what is the structure of F₁?

(αβ)₃ and γ stalk

(αβ)₃ structure and function?

spherical structure; has ATPase activity

γ stalk

rotor stalk; connects c-ring (tightly associated) to (αβ)₃ (loosely associated, sits deep in)

what is the F₁F₀ ATPase basic mechanism? (2 steps)

1. while H+ passes through F₀, the rotor rotates relative to the stator; H+ gradient → rotation

2. while rotor rotates, F₁ synthesizes ATP from ADP and phosphate; rotation → ATP synthesis

explain the mechanism of F₀ rotation (4 steps)

1. a-subunit has two half-channels for H+; H+ enters in first channel from intermembrane space/outside the mitochondria

2. each c-subunit has a proton-acceptor, which receives proton from a half-channel

3. after accepting proton, c-ring slides by one subunit, then next H+ comes through the half-channel and binds next c-subunit, then c-ring rotates by one subunit….

4. after one round of rotation (12 H+), H+ is transferred from c-subunit to another half-channel that is open to the opposite side

how does rotation of the γ stalk make ATP in F₁?

as γ stalk rotates in F₁ ATPase, three αβ subunits change conformation

what are the 3 conformations that the γ stalk can change the αβ subunits to?

open, tight, low-affinity conformations

O (open) conformation

has low affinity to ATP and can exchange ATP/ADP; will release ATP and then bind ADP + P_i

T (tight) conformation

can only bind ATP, never release it; converts ADP + P_i to ATP

L (low-affinity) conformation

binds ADP and P_i, but they can’t escape form the protein

how many ATP are produced per one complete turn of the γ stalk in F₁ ATPase?

3

___ H+ can produce ___ ATP

4, 1

how many H+ and ATP can one matrix NADH produce?

12 H+ and 3 ATP

how many H+ and ATP can one FADH₂ produce?

8 H+ and 2 ATP

how many H+ and ATP can one cytosolic NADH produce? (60% efficient)

7.2 H+ and 1.8 ATP