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Questions and Answers
What does a change in free energy (∆G) predict during a reaction?
What does a change in free energy (∆G) predict during a reaction?
The direction in which that reaction will spontaneously proceed.
If ∆G is positive, then the reaction is spontaneous.
If ∆G is positive, then the reaction is spontaneous.
False
What do you call the pathway that consists of electron carriers in the mitochondria?
What do you call the pathway that consists of electron carriers in the mitochondria?
Electron transport chain.
The reduced coenzymes that donate electrons are ___ and ___.
The reduced coenzymes that donate electrons are ___ and ___.
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What happens to protons (H+) during electron transport?
What happens to protons (H+) during electron transport?
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What is the role of cytochrome c oxidase?
What is the role of cytochrome c oxidase?
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Uncoupling proteins dissipate the H+ gradient in mitochondria.
Uncoupling proteins dissipate the H+ gradient in mitochondria.
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What are aldoses?
What are aldoses?
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Which enzymes produce monosaccharides in the small intestine?
Which enzymes produce monosaccharides in the small intestine?
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The condition caused by the age-dependent loss of lactase is called ___ intolerance.
The condition caused by the age-dependent loss of lactase is called ___ intolerance.
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Study Notes
Free Energy and Reaction Spontaneity
- Reactions with a negative change in free energy (∆G) are spontaneous, meaning they proceed without external input of energy.
- Reactions with a positive ∆G require energy to proceed.
- Reactions with a ∆G of zero are at equilibrium.
- The forward and reverse reactions have equal but opposite ∆G values.
- ∆G is additive for consecutive reactions.
ATP Hydrolysis and Energy Coupling
- Reactions with large positive ∆G can be driven by coupling with reactions that have a large negative ∆G, such as ATP hydrolysis.
Electron Transport Chain
- NADH and FADH2 donate electrons to the electron transport chain, composed of FMN, iron-sulfur centers, coenzyme Q, and heme-containing cytochromes.
- The electron transport chain is located in the inner mitochondrial membrane.
- Electrons flow from fuels to oxygen, which has a high reduction potential.
- Cytochrome c oxidase is the only cytochrome that can bind oxygen.
Oxidative Phosphorylation
- Electron transport pumps protons (H+) from the mitochondrial matrix to the intermembrane space.
- This creates an electrochemical gradient across the inner mitochondrial membrane.
- Protons re-enter the matrix through ATP synthase, driving the synthesis of ATP.
Uncoupling Oxidative Phosphorylation
- Uncoupling protein 1 (UCP1) in brown adipose tissue dissipates the proton gradient, releasing energy as heat.
- Synthetic compounds like 2,4-dinitrophenol and aspirin also uncouple oxidative phosphorylation.
Mitochondrial DNA
- Mutations in mitochondrial DNA, inherited maternally, can cause mitochondrial diseases.
Apoptosis
- The release of cytochrome c into the cytoplasm triggers apoptosis through activation of caspases.
Monosaccharides
- Monosaccharides with an aldehyde group are called aldoses; those with a keto group are called ketoses.
Disaccharides, Oligosaccharides, and Polysaccharides
- These are formed when monosaccharides are linked by glycosidic bonds.
Isomers and Epimers
- Isomers have the same chemical formula but different structures.
- Epimers are isomers that differ in configuration around one carbon atom.
Enantiomers
- Enantiomers are mirror images of each other and are designated as D- and L-isomers.
Reducing Sugars
- When an aldehyde group of a sugar is oxidized, it becomes a reducing sugar.
Anomeric Carbon
- Cyclization of a sugar creates an anomeric carbon from the carbonyl carbon.
- α and β anomers differ in the configuration around this carbon.
N- and O-glycosidic Bonds
- Sugars can form glycosidic bonds with --NH2 or --OH groups.
Carbohydrate Digestion
- Salivary and pancreatic α-amylase break down polysaccharides (starch and glycogen) into oligosaccharides.
- Disaccharidases (lactase, sucrase, isomaltase, and maltase) in the small intestine break down disaccharides into monosaccharides.
Carbohydrate Absorption
- Monosaccharides are absorbed by specific transporters in the small intestine.
Carbohydrate Malabsorption
- Deficiencies in carbohydrate digestion can lead to undigested carbohydrates reaching the large intestine.
- Bacterial fermentation of these carbohydrates can cause diarrhea, gas, and abdominal cramps.
- Lactose intolerance is a common example, caused by a decline in lactase activity.
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Description
This quiz covers essential concepts regarding free energy changes in chemical reactions, including spontaneity and equilibrium. It also delves into ATP hydrolysis and its role in energy coupling and the mechanics of the electron transport chain. Test your understanding of these crucial biochemical processes!
