BIOG 1440 Lecture Notes - Lecture 3: Cell Membrane, Lipid Bilayer, Facilitated Diffusion

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ivoryscorpion883

1 Feb 2018

School

Cornell University

Department

Biology: General Courses

Course

BIOG 1440

Professor

Shapleigh

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Document Summary

Osmosis: diffusion of free water across a selectively permeable membrane, like a plasma membrane: more technically, movement of solvent across a selectively permeable membrane into a region of higher solute concentration, solvent=water; solute=basically anything else ii. Problems associated with osmosis: tonicity: the ability of a surrounding sol"n to cause a cell to gain or lose water. Isotonic solution: solute concentration is the same as that inside. Cells with strong walls more resistant to hypotonicity: hypotonic plant cells normally swollen (turgid) Structural evidence for alternating access hypothesis: energy is used to drive structural changes which allow transport against a concentration gradient, no atp, protein exists in either open or closed configurations. In the presence of a modified form of atp (amppnp) the protein is mostly in outward configuration: active transport is also used to drive ion transport. Sodium-potassium pump is one type of active transport system.

Related Questions

1. predict the direction of water movement based on differences in solute concentrations. Use the terms osmotic pressure, hypotonic, isotonic, and hypertonic
2. Why do membranes have to be selectively permeable?

3. What determines whether a particular substance can diffuse (simple or facilitated) through a membrane?

4. What mechanisms drive molecules across membranes? Use the terms concentration gradient, (facilitated) diffusion and active transport.
5. Which parts of the plasma membrane proteins do you expect to be hydrophobic or hydrophilic? Justify your answer.
concise and short answers pls

Read the following scenarios and indicate which of the following processes they describe.

11. Sodium molecules move randomly around a solution of sodium chloride in water, frequently colliding with other sodium ions and chloride ions. secondary active transport diffusion osmosis facilitated diffusion primary active transport

12. Sodium ions (Na+) move through sodium channels in a synthetic membrane. primary active transport secondary active transport facilitated diffusion osmosis

13. Water molecules move into the cytosol of a cell placed in a hypotonic solution. primary active transport secondary active transport facilitated diffusion osmosis

14. Water molecules move into the cytosol of a cell placed in pure water. facilitated diffusion osmosis secondary active transport primary active transport

15. Water molecules move out of a cell placed in a hypertonic solution. facilitated diffusion primary active transport secondary active transport osmosis

16. The action of sodium-potassium pumps moves sodium ions (Na+) out of a cell and potassium ions (K+) into a cell. facilitated diffusion secondary active transport osmosis primary active transport

17. Glucose molecules move into cells lining the intestine against their concentration gradient driven by the movement of sodium ions (Na+) into the cells down their concentration gradient. osmosis secondary active transport primary active transport facilitated diffusion

18. A beaker of water is separated by a selectively permeable membrane that allows the passage of water but not ions. A solution of 4% sodium chloride (NaCl) is placed on one side of the membrane and pure water is placed on the other side of the membrane. The solutions are allowed to equilibrate. At this point, which process is going on? facilitated diffusion osmosis secondary active transport primary active transport

amaranthelk944

1 Which of the following statements is false?

(a) CO₂ and O₂ can diffuse freely across the cell membranes.

(b) The differences in permeability between artificial lipid bilayers and cell membranes arise from variations in phospholipid content.

(d) Cells expend energy in the form of ATP hydrolysis to maintain ion concentrations that differ from those found outside the cell.

2 Cells use membranes to help maintain set ranges of ion concentrations inside and outside the cell. Which of the following ions is the most abundant inside a typical mammalian cell?

(a) Na⁺

(b) K⁺

(d) Cl^â

3 Pumps are transporters that are able to harness energy provided by other components in the cells and drive the movement of solutes across membranes, against their concentration gradient. This type of transport is called _____________.

(a) active transport.

(b) free diffusion.

(d) passive transport.

harlequinbuffalo618

BIOG 1440 Lecture Notes - Lecture 3: Cell Membrane, Lipid Bilayer, Facilitated Diffusion

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