Biochem EX1 - Oxidative Phosphorylation Flashcards
Production of ATP for energy is the goal of oxidative phosphorylation. One of the other pathways in which ATP may be directly produced is?
Glycolysis. However, oxidative phosphorylation is much more efficient.
What are the three foodstuffs that can be the source of reducing equivalents whose oxidation may be coupled to generation of ATP? What are five types of molecules that are commonly derived from these foodstuffs? (Hint-see figure 13-2 for help answering both questions).
Proteins, fats, & carbohydrates are the foodstuffs that can be the source of reducing equivalents whose oxidation may be coupled to generation of ATP.
Ketone bodies, amino acids, fatty acids + glycerol, & monosaccharides are the five types of molecules that are commonly derived from these foodstuffs
What two vitamins form part of dinucleotide electron carriers used for oxidative phosphorylation? What iron-containing biomolecule forms part of cytochrome electron carriers used in the electron chain?
- Niacin (Vitamin B3) –> NAD+
- Riboflavin (Vitamin B2) –> FAD
Cytochrome C (contains heme)
Describe the architecture of a mitochondrion, including the inner and outer membranes, the intermembrane space, the cristae, and the matrix. Where are complexes I through V located? (Hint-see figure 13-1 for help answering both questions).
Mitochondria have two membranes, each composed of a phospholipid bilayer. The inner membrane encloses and convolutes into the mitochondrial matrix, forming cristae. This serves to increase the surface of the inner membrane, which carries the main enzymatic machinery of oxidative phosphorylation. The mitochondrial matrix contains a range of enzymes, which form parts of major metabolic pathways. The enzymatic machinery of oxidative phosphorylation, leading to ATP production, is mainly located in the inner mitochondrial membrane.
Complexes I through V are located in the inner membrane in between the matrix and intermembrane space.
What results from the NADH and FADH2 hydrogens? Where does a hydrogen electron go? Where does a hydrogen proton go?
The proton gradient in the intermembrane space results from NADH and FADH2 hydrogens.
Hydrogen electrons travel through the complexes in the inner membrane.
Hydrogen protons travel to the intermembrane space where the proton gradient is produced.
What electron carrier does Complex I accept electrons from? What electron carrier does Complex II accept electrons from? What complexes does Complex III accept electrons from, and what complex does Complex III pass electrons to? Which of the complexes do protons pass through?
Complex I accepts NADH where it is oxidized to NAD+
Complex II accepts electrons from FADH2
Complex III accepts electrons from CoQ.
Complex III passes electrons to cytochrome C to give to complex IV.
Protons pass through I, III, & IV
Which results in more energy in terms of ATP produced, electrons passed via Complex I or electrons passed via Complex II?
Electrons passed via Complex I because there are no protons pumped from Complex II.
(NADH > FADH2)
CoQ10 is sold as a nutritional supplement in many retail pharmacies with claims touting its efficacy for everything from curing heart failure and cancer. Existing evidence that CoQ10 as a supplement does anything worthwhile is weak, and very likely not valid. For certain claims, the evidence is that the claims are untrue. What is the role of CoQ10 in oxidative phosphorylation, and what rationale do those who sell it propose to pretend it might have a benefit? What is another name for CoQ10?
CoQ10 is an essential cofactor in mitochondrial oxidative phosphorylation, and is necessary for ATP production. In this role, CoQ10 acts as a mobile electron carrier. Those who sell it rationale that ATP production will be increased giving you more energy throughout the day.
CoQ10 is also known as Ubiquinone
Where is the energy derived from that drives protons through the complexes into the intermembrane space, despite that being an acidic and positively charged compartment? What is the name of this unfavorable gradient?
Due to the accumulation of H+ in the intermembrane space there is also an accumulation of positive charges here. This creates an electrochemical gradient powering the formation of ATP.
Electrochemical Proton gradient.
What important event happens on Complex IV?
H2O is reduced to O2
What important event happens on Complex V? What force drives this event? What are two other names for Complex V? What does the ‘o’ of F1Fo-ATPase stand for?
Important event: It drives the synthesis of ATP from ADP and phosphate (Pi).
What force drives this event: A proton gradient across a membrane.
Two other names for Complex V: ATP Synthase & F1Fo ATPase
O stands for: Oligomysin
As one can imagine, proper function of oxidative phosphorylation is critical to animal life. What steps are inhibited by the deadly poisons cyanide, rotenone, amobarbital (okay, so this is a drug too), and 2,4-dinitrophenol?
- Cyanide blocks complex IV
- Rotenone & Amobarbital block oxidative phosphorylation at Complex I
- 2,4-dinitrophenol blocks protons from going through complex IV. (Uncoupler)
What does the uncoupling protein UCP1 do?
Non shivering Thermogenesis: Production of heat without shivering.
What does UCP1 allow newborns not to do?
It allows babies to produce heat through non shivering thermogenesis.
Why is brown adipose tissue called brown adipose tissue (it has high UCP1 and what else is high)?
Brown adipose tissue has so many mitochondria that it changes color. This is due to the fact that it is accommodating to the presence of UCP1
