Flashcards in Lecture 9 Deck (18):
As pyruvate enters the mitochondrion, a multienzyme complex modifies pyruvate to acetyl CoA which enters the Krebs cycle in the matrix.
Uses No oxygen
A protein complex, ATP synthase, in the cristae actually makes ATP from ADP and Pi
The ATP synthase molecules are the only place that will allow H+ to diffuse back to the matrix.
The mechanism of ATP generation by ATP synthase is still an area of active investigation.
? As hydrogen ions flow down their gradient, they cause the cylinder portion and attached rod of ATP synthase to rotate.
? The spinning rod causes a conformational change in the knob region, activating catalytic sites where ADP and inorganic phosphate combine to make ATP.
? a catabolic process: uses oxygen as a reactant to complete the breakdown of a variety of organic molecules.
Organic compounds + O2 -> CO2 + H2O + Energy
? Carbohydrates, fats, and proteins can all be used as the fuel, but it is traditional to start learning with glucose.
C6H12O6 + 6O2 -> 6CO2 + 6H2O + Energy (ATP + heat)
? In cellular respiration, Glucose is oxidized, oxygen is reduced.
? Most of the processes in cellular respiration occur in mitochondria.
? The catabolism of glucose is exergonic with a delta G of 686 kcal per mole of glucose.
? Some of this energy is used to produce ATP that will perform cellular work.
? Cellular respiration does not oxidize glucose in a single step that transfers all the hydrogen in the fuel to oxygen at one time.
? glucose and other fuels are broken down gradually in a series of steps, each catalyzed by a specific enzyme.
inner membrane of the mitochondrion
electron transport Chain
A sequence of
electron carrier molecules (membrane proteins)
that shuttle electrons down a series of
redox reactions that release energy used to
: a catabolic process, leads to the partial degradation of sugars in the absence of oxygen
During glycolysis: glucose is split in two
? First glucose is broken in half, then these smaller sugars are oxidized and rearranged to form two molecules of pyruvate.
? Each of the ten steps in glycolysis is catalyzed by a specific enzyme.
? These steps can be divided into two phases:
1-energy investment phase 2-energy payoff phase
? Details of glycolysis
? In the energy investment phase, ATP provides activation energy by phosphorylating glucose.
? This requires 2 ATP per glucose.
? Energy payoff phase
? 2 ATP (net)
2 molecules of pyruvate are produced per glucose.
? The net yield from glycolysis is, per glucose:
? 2 ATP
? 2 NADH
? 2 molecules of pyruvate
? There is no CO2 is produced during glycolysis.
? Glycolysis occurs whether O2 is present or not.
? If O2 is present pyruvate moves to the Krebs cycle and the energy stored in NADH can be converted to ATP by the electron transport system and oxidative phosphorylation.
? Glycolysis occurs in the cytoplasm
? Some ATP is also generated in glycolysis and the Krebs cycle by substrate-level phosphorylation.
A chemical cycle involving
eight steps that completes the metabolic
breakdown of glucose molecules begun in
glycolysis by oxidizing acetyl CoA (derived
from pyruvate) to carbon dioxide; occurs within the mitochondrion in eukaryotic cells
and in the cytosol of prokaryotes; together
with pyruvate oxidation, the second major
stage in cellular respiration.
of the mitochondrion enclosed by the inner
membrane and containing enzymes and
substrates for the citric acid cycle, as well as
ribosomes and DNA.
nicotinamide adenine dinucleotide
refers to the loss of electrons to any electron acceptor, not just to oxygen
Creating ATP through the ETC
involve a change in the degree of electron sharing
addition of electrons