Download Respiration II

Respiration II
Does NADH have more or less potential p
energy than NAD+? Explain why or why not.
What is a “proton motive force?” Oxygen has a very low redox potential, so it pulls low‐
energy electrons out of the ETC efficiently.
gy
y
Suppose a mutation allowed some humans to breathe in sulfur dioxide, instead of oxygen. Sulfur dioxide has a hi h
higher redox
d potential than oxygen. i l h
Would these mutants have complex IV? Would they produce more or less ATP than wild‐type humans? SO2
Krebs Cycle: An overview
A i
A series of carboxylic acids is oxidized
f b li
id i
idi d
Citrate
Isocitrate
-Ketoglutarate
Succinyl CoA
Succinate
Fumarate
Malate
Oxaloacetate
More reduced
More oxidized
Why is it considered a cycle?
6C
‘Incoming’
Citrate
Isocitrate
2C
Oxaloacetate
5C
4C
Malate
Fumarate
-Ketoglutarate
Succinyl CoA
Are the enzymes that catalyze y
y
each reaction lined up, either side by side or in a circular formation?
Succinate
What are the 6 C, 5 C, 4 C etc. What
are the 6 C 5 C 4 C etc
labels all about? Krebs Cycle: Key observations
• Starts with Acetyl CoA
• ____ reactions, each reactions each
turn of the cycle
Of these:
• ___ yield(s) NADH or FADH2
or FADH
• ___ yield(s) ATP or GTP
• ___ is/are “d
“decarboxylation”
b l ti ”
Krebs Cycle: Succinate  Fumarate is a redox reaction
How many C‐H and C‐C bonds in succinate versus fumarate? O‐— C = O
FAD
O‐— C = O
H — C — H C — H H — C — H C — H O‐— C = O O‐— C = O FADH2
How many electrons and protons move from succinate to FAD? How many electrons and protons move from succinate
to FAD?
Working backwards through cellular respiration: The citric acid cycle 1) completes the oxidation of glucose it i
id
l 1)
l t th
id ti
f l
(releases CO2); and 2) produces NADH and FADH2 that feed the ETC
feed the ETC.
What does it mean to say that glucose has been completely oxidized? III. How does pyruvate processing produce NADH?
CoA
NOTE: the 4 NADH/FADH
NOTE:
the 4 NADH/FADH2 and and
the 1 ATP/GTP from the Krebs cycle are produced via oxidation
cycle are produced via oxidation of 4 C‐C/C‐H bonds in this acetyl group. Explain why the following statement is accurate: During cellular respiration, most of the energy in During
cellular respiration most of the energy in
glucose ends up in two acetyl groups. Working backwards through cellular respiration: Pyruvate
processing 1) converts pyruvate to acetyl CoA; 2) produces processing 1) converts pyruvate
to acetyl CoA; 2) produces
NADH that feeds the ETC, 3) releases CO2. Mitochondrial matrix Inner membrane
y
moves into the mitochondrion via co‐
NOTE: Pyruvate
transport, against its electrochemical gradient. Glycolysis: from glucose to pyruvate
Glucose
Trapping Step
Commitment Step
Why do people talk about an “energy investment phase” of glycolysis
f l l i and an “energy payoff phase”? d “
ff h ”?
The glycolytic
The
glycolytic enzymes are found in nearly all organisms. enzymes are found in nearly all organisms
What does this observation imply about the evolution of glycolysis? Working backwards through cellular respiration: Working
backwards through cellular respiration:
Glycolysis 1) converts glucose to two molecules of pyruvate; 2) yields 2 ATP; and 3) yields 2 NADH. Cytoplasm Mitochondrial matrix Inner membrane
Label glycolysis, pyruvate
py
processing, citric acid cycle.
In terms of redox
chemistry where
chemistry, where is the “action” (the big potential
(the big potential energy drops) in glucose oxidation? Glucose
Pyruvate
Acetyl CoA
Oxaloacetate