
Concept explainers
(a)
To identify: Whether ethanol is likely to cross a membrane by mediated or non-mediated transport.
Concept introduction: The free energy change for moving a substance across a membrane depends upon the concentrations on both sides of the membrane, and in case of ions, free energy change depends upon the membrane potential. Some membrane permeable substance can cross the membrane, but some substance cannot be diffused directly across a membrane; it needs some protein-based mediator to move across the plasma membrane of the cell. Non-mediated transport is the process of simple diffusion. Mediated transport is constituted through the action of definite carrier protein molecules.
(b)
To identify: Whether glycine is likely to cross a membrane by mediated or non-mediated transport.
Concept introduction: The free energy change for moving a substance across a membrane depends upon the concentrations on both sides of the membrane, and in case of ions, free energy change depends upon the membrane potential. A substance cannot be diffused directly across a membrane; it needs some protein-based mediator to move across the plasma membrane of the cell. Non-mediated transport is the process of simple diffusion. Mediated transport is constituted through the action of definite carrier protein molecules.
(c)
To identify: Whether cholesterol is likely to cross a membrane by mediated or non-mediated transport.
Concept introduction: The free energy change for moving a substance across a membrane depends upon the concentrations on both sides of the membrane, and in case of ions, free energy change depends upon the membrane potential. A substance cannot be diffuse directly across a membrane; it needs some protein-based mediator to move across the plasma membrane of the cell. Non-mediated transport is the process of simple diffusion. Mediated transport is constituted through the action of definite carrier protein molecules.
(d)
To identify: Whether ATP is likely to cross a membrane by mediated or non-mediated transport.
Concept introduction: The free energy change for moving a substance across a membrane depends upon the concentrations on both sides of the membrane and in case of ions, free energy change depends upon the membrane potential. A substance cannot be diffused directly across a membrane; it needs some protein-based mediator to move across the plasma membrane of the cell. Non-mediated transport is the process of simple diffusion. Mediated transport is constituted through the action of definite carrier protein molecules.

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Chapter 10 Solutions
Fundamentals of Biochemistry: Life at the Molecular Level
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- 1. Which one is the major organic product obtained from the following aldol condensation? O NaOH, H₂O heat A B C D Earrow_forwardAn organic chemist ordered the wrong item. She wanted to obtain 1-hydroxy-2-butanone, butinstead ordered 2-hydroxybutyraldehyde. As a good biochemist, show how the organic chemistcould use biological catalysis to make her desired compound. Please show the mechanism by drawing.arrow_forwardShow the fate of the hydrogen on carbon-2 of glucose. Please draw out the structure using curve arrows to show electron flow.arrow_forward
- 3. Which one of the compounds below is the major product formed by the reaction sequence shown here? CH3 + CH3NO2 NaOH H2, Ni ? nitromethane acetophenone OH OH HO HN- u x x x x Ph A HO -NH2 HO H Ph Ph Ph N- H B Ph NH2 D Earrow_forward4. Only ONE of the five compounds below can be prepared by an aldol condensation in which a single carbonyl compound is treated with base. Which one is it? To solve this problem, reverse the aldol condensation that formed each of these molecules to find out what two molecules came together to make the products. The one in which the two molecules are identical is the answer. Ph Ph ཚིག གནས ག ནཱ ཀ ན ཀནཱ A Ph H B Ph Ph H D Ph. Ph Ph E Harrow_forward5. Which one is the major organic product obtained from the following reaction sequence? First, equimolar amounts of cyclopentanone and LDA are mixed at -78°C. Then propionaldehyde (propanal) is added. Addition of aqueous acid completes the process. LDA, -78°C. 1. 2. H₂O* H A B H 0 D H H Earrow_forward
- 2. Which one is the major organic product obtained from the following reaction? NaOH, H₂O heat A B C D Earrow_forwardCH3CH2CHO + propanal PhCH2CHO 2-phenylacetaldehyde mixture of four products NaOH 10. In the crossed aldol reaction of propanal and 2-phenylacetaldehyde shown above, a mixture of four products will be formed. Which ONE of the compounds below will NOT be formed in this crossed aldol reaction? OH Ph A H OH OH Ph H B OH OH H H H Ph Ph C Ph D Earrow_forwardAn organic chemist ordered the wrong item. She wanted to obtain 1-hydroxy-2-butanone, butinstead ordered 2-hydroxybutyraldehyde. As a good biochemist, show how the organic chemistcould use biological catalysis to make her desired compound.arrow_forward
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