The sum of all chemical reactions involved in maintaining the dynamic state of a cell or organism
metabolism
A series of biochemical reaction
pathway
The process of breaking down large nutrient molecules into smaller molecules with the concurrent production of energy
catabolism
The process of synthesizing larger molecules from smaller ones
anabolism
where replication of DNA takes place within a cell
nucleus
Part of the cell which removes damaged cellular components and some unwanted foreign materials
lysosomes
Cell structure which packages and processes proteins for secretion and delivery to other cellular components
golgi bodies
Organelles in which the common catabolic pathway takes place in higher organisms
mitochondria
What is the purpose of the common catabolic pathway?
To convert the energy stored in food molecules into energy stored in molecules of ATP
The 2 parts to the common metabolic pathway
citric acid cycle
oxidative phosphorylation
4 principal compounds participating in the common catabolic pathway
1. AMP, ADP, ATP
2. NAD+/NADH
3. FAD/FADH2
4. Coenzyme A
Agents for the storage and transfer of phosphate groups
AMP/ADP/ATP
Agents for the transfer of electrons in biological oxidation-reduction reactions
NAD+/NADH
Agents for the transfer of electrons in biological oxidation-reduction reactions
FAD/FADH2
Agent for the transfer of acetyl groups
Coenzyme A
2 electron carriers in oxidative phosphorylation
coenzyme Q and cytochrome c
3 redox states of coenzyme Q
Quinone
Semiquinone
Quinol
Main components of Complex I
flavoprotein
iron sulfur clusters (FeS)
coenzyme Q (ubiquinone)
What takes place in complex I?
NADH is oxidized to NAD+
NADH + H+ + CoQ = NAD+ + CoQH2 + energy
Oxidizing agent used in Complex I
CoQ, which is reduced to CoQH2
What happens to protons from the oxidation of NAD+ in Complex I?
Some of the energy released in the oxidation moves 2H+ from the matrix to the intermembrane space
What reaction takes place in Complex II?
Oxidation of FADH2 to FAD
FADH2 + CoQ = FAD + CoQH2 + energy
Oxidizing agent in Complex II
CoQ, which is reduced to CoQH2
FADH2 + CoQ = FAD + CoQH2 + energy
What happens to protons in Complex II?
The energy released in this reaction is not sufficient to pump protons across the membrane.
What happens in Complex III?
Electrons from CoQH2 are delivered to cytochrome c (Cyt c)
CoQH2 + 2Cyt c (reduced) = CoQ + 2H+ + 2Cyt c (oxidized)
Main components of Complex III
cytochrome b
cytochrome c
FeS clusters
What happens to protons in Complex III?
It has 2 channels through which 2 H+ are pumped from the matrix into the intermembrane space
Complex IV is also known as ______.
cytochrome oxidase
Important subunit of Complex IV
cytochrome a3
How do electrons flow from Complex III to Complex IV?
electrons flow from oxidized Cyt c in Complex III to Cyt a3 in Complex IV
From Cyt a3, electrons are transferred to O2
O2 + 4H+ + 4e- = 2H2O + energy
How are protons pumped in Complex IV?
H+ are pumped from the matrix into the intermembrane space
In all 4 Complexes together...
How many H+ are pumped out per NADH and per FADH2?
6 H+ per NADH
4 H+ per FADH2
Explain how electron and H+ transport produce the chemical energy of ATP.
Chemiosmotic Pump...
A pH gradient is produced across the inner mitochondrial membrane
There is a higher concentration of H+ in the intermembrane space than inside the mitochondria
This propels protons back into the mitochondrion through the enzyme comple
Oxidation of each NADH gives how many ATP?
3
Oxidation of each FADH2 gives how many ATP?
2
The yield of ATP per 2-carbon acetyl group oxidized to CO2 is _____.
12 ATP
Complex I to II reaction
1. Electrons are transferred from NADH to FMN, then to FeS clusters, then to Q
2. In Complex II, FADH2 is formed during the conversion of succinate to fumarate
3. Electrons pass to Q via FeS clusters
NADH + H+ is fed into which complex?
1, 3, and 4
FADH2 is fed into which complex?
2
WHich complex does not push out hydrogen ions in the intermembrane space?
complex 2
Which complex produces water?
complex 4
What is an uncoupler?
They dissociate oxidation in the respiratory chain from phosphorylation
What is thermogenin?
uncoupling protein found in brown adipose tissue that functions to generate body heat
Competitive inhibitor of Complex II
malonate
Inhibits oxidative phosphorylation by inhibiting the transporter of ADP into and ATP out of the mitochondrion
atractyloside
Antibiotic which completely blocks oxidation and phosphorylation by blocking the flow of protons through ATP synthase
oligomycin
Oligomycin is an inhibitor for what conversion?
blocks phosphorylation of ADP to ATP
Most frequently used uncoupler
2,4-dinitrophenol
Condition which involves severe diminution or absence of most oxidoreductases of the respiratory chain
Fatal infantile mitochondrial myopathy and renal dysfunction
An inherited condition due to NADH-Q oxidoreductase (Complex I) or cytochrome oxidase (Complex IV) deficiency. It is caused by a mutation or mitochondrial DNA and may be involved in Alzheimer's Disease and diabetes mellitus
Mitochondrial encephalopathy, lactic acidosis, and stroke
(MELAS)
HS2, CO, and CN- are toxins and inhibitors for what Complex?
Complex 4