Lecture 3 - Bioenergetics and Biological Oxidations Flashcards
The conversion of glucose to pyruvate (glycolysis) results in the net synthesis of:
2 ATP
2 NADH
The oxidation of acetyl-CoA to CO2 (the TCA cycle) results in the synthesis of:
1 GTP
3 NADH
1 FADH2
Oxidation of fatty acids does not directly produce high energy phosphate bonds, but for each cycle of oxidation, what is produced?
1 NADH
1 FADH2
The oxidation of NADH and FADH2 by the electron transport chain results in the synthesis of:
3 (2.5) or 2 (1.5) ATP
The 3 major reactions for interconversions of Adenine Nucleotides (ATP, ADP, AMP) are:
- Kinase-catalyzed reactions
- Myokinase (adenylate kinase) reactions
- Nucleoside diphosphate kinase reactions
Myokinase (adenylate kinase) is present in high concentrations in _____.
muscle - it is associated with the myofibril
May regulatory enzymes in metabolic pathways are allosterically regulated by:
the adenylate nucleotides
The three types of enzymes that catalyze oxidation and reduction reactions are:
- Dehydrogenases
- Oxidases
- Oxygenases
Which is NOT a principal difference between NAD+ and NADP+?
A. NADP+ has an additional phosphate group on the ribose moiety
B. NAD+ participates primarily in catabolic pathways which tend to be oxidative in nature
C. NADPH participates mainly in biosynthetic anabolic pathways which are usually reductive in nature
D. NADP/NADPH is found in the cytosol and cannot cross the inner mitochondrial membrane
E. All of the following are principal differences
E
Pellegra, characterized by dermatitis, diarrhea, and dementia, is a deficiency of what cofactor?
Niacin (vitamin B3)
Nicotinamide Coenzymes are synthesized from _______ and ______.
Niacin and Tryptophan
Flavin coenzymes are derived from _______.
Riboflavin
Which type of reaction is catalyzed by dehydrogenases requiring nicotinamide coenzymes?
A. Alcohol –> Aldehyde
B. Aldehyde –> Alcohol
C. Keto –> Alcohol
D. Carbon-carbon double bond formation
A - dehydrogenases requiring nicotinamide coenzymes also catalyze Alcohol –> Keto reactions
What part of FAD is involved in the transfer of electrons?
A ring system containing nitrogen atoms (isoalloxazine ring)
Which type of reaction is catalyzed by dehydrogenases requiring flavin coenzymes?
A. Alcohol –> Aldehyde
B. Aldehyde –> Alcohol
C. Keto –> Alcohol
D. Carbon-carbon double bond formation
D
______ catalyze the transfer of electrons from some organic substrate to molecular oxygen via an intermediate carrier.
oxidases
________ catalyze hydroxylation of some organic substrate.
monooxygenases
Enzymes involved in the hydroxylation of proline and lysine residues of collagen are examples of what class of enzymes?
dioxygenases
How are monooxygenases different from dioxygenases?
They incorporate only one of the oxygen atoms into a substrate (the other oxygen gets reduced to H2O).
The monooxygenases require a source of reducing power to reduce molecular oxygen to a hydroxyl group and water. The reducing power is supplied by ________.
NADPH
What are the 3 proteins that constitute the miniature electron transport chain embedded in the microsomal (SER) membrane?
- Flavoprotein
- Non-heme iron protein
- Cytochrome P450
Where are monooxygenases usually located? (2 locations)
- Mitochondria (steroid hydroxylation reactions)
2. Microsomes (hydroxylation reactions)
The 3 major ROS are:
- Superoxide (O2-)
- Hydrogen peroxide (H2O2)
- Hydroxyl radical
What enzyme generates H2O2 in the process of detoxifying the superoxide radical?
SOD (Superoxide dismutase)
What enzymes reduce hydrogen peroxide to H2O?
Peroxidases
What enzymes catalyze the dismutation of hydrogen peroxide to H2O?
Catalase
There are two sources of hydrogen peroxide. One is formation by SOD in the process of detoxifying the superoxide radical. The other is via:
Oxidase-Catalyzed Reactions (includes peroxisomal reactions catalyzed by FAD-dependent oxidases, such as amino acid oxidases and the first reaction in the oxidation of fatty acids)
Most of the hydrogen peroxide is produced, and the excess destroyed in the __________.
peroxisomes
