Table of contents

1. Overview of Cell Biology2h 49m
2. Chemical Components of Cells1h 14m
3. Energy1h 33m
4. DNA, Chromosomes, and Genomes2h 31m
5. DNA to RNA to Protein2h 31m
6. Proteins1h 36m
7. Gene Expression1h 42m
8. Membrane Structure1h 4m
- The Lipid Bilayer
  38m
- Membrane Proteins
  25m
9. Transport Across Membranes1h 52m
10. Anerobic Respiration1h 5m
11. Aerobic Respiration1h 11m
12. Photosynthesis52m
13. Intracellular Protein Transport2h 18m
14. Cell Signaling1h 28m
15. Cytoskeleton and Cell Movement1h 39m
16. Cell Division3h 5m
17. Meiosis and Sexual Reproduction50m
18. Cell Junctions and Tissues48m
19. Stem Cells13m
- Stem Cells
  13m
20. Cancer44m
21. The Immune System1h 6m
22. Techniques in Cell Biology1h 41m

9. Transport Across Membranes

Principles of Transmembrane Transport

Cell Biology

9. Transport Across Membranes

Principles of Transmembrane Transport

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Multiple Choice

Transporter proteins transport solutes across the membrane via which of the following mechanisms?

Conformational changes that move the solute across the membrane

Formation of open pores that allow free diffusion

Passive diffusion through the lipid bilayer

Direct hydrolysis of ATP at the membrane surface

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Verified step by step guidance

Understand the role of transporter proteins: Transporter proteins are integral membrane proteins that facilitate the movement of specific solutes across the lipid bilayer. They are highly selective and often require specific mechanisms to function.

Eliminate incorrect options: Passive diffusion through the lipid bilayer does not involve transporter proteins. Instead, it refers to the movement of small, nonpolar molecules directly through the lipid bilayer without assistance.

Analyze the mechanism of open pores: Formation of open pores that allow free diffusion is characteristic of channel proteins, not transporter proteins. Transporter proteins do not create open pores but instead undergo conformational changes.

Consider the role of ATP hydrolysis: Direct hydrolysis of ATP at the membrane surface is a feature of ATP-driven pumps (a type of active transport), but not all transporter proteins rely on ATP hydrolysis. Some work via facilitated diffusion without energy input.

Identify the correct mechanism: Transporter proteins operate by undergoing conformational changes that move the solute across the membrane. This mechanism ensures specificity and controlled transport of solutes.