Membrane proteins move laterally in a phospholipid bilayer but generally not up and down. Why would this be so?

The cytoplasm of a certain cell is composed of a solution that is 98% water, 2% solutes. Consider the solution shown in the beaker in this picture: FOOE OOS Foor solution. [Select] Cytoplasm is 98% water, 2% solutes. The solution in the beaker would be considered when compared to [Select] The plasma membrane is impermeable to solutes. Beaker solution is 98% water, 2% solutes the cell. We would expect that the cell would [Select] if it was placed in the would account for whatever changes might occur to the volume of the cytoplasm of the cell when it is placed in the solution.

Distinguish molecules that can diffuse through a lipid bilayer from those that must be transported. Describe the transport of small molecules by carrier proteins, and contrast ion channels and pores. Explain how ion gradients can drive active transport across membranes.

Identify how each of the following would pass through the plasma membrane: gases, large polar molecules, charged molecules (like ions), hydrophobic molecules, and small polar molecules. Be specific.

IN the figure for D: The organization of a protein that normally resides in the plasma membrane in shown in the figure below. The boxes labeled 1,2 3 and 4 represent membrane-spanning sequences and the arrow represents a site of action of signal peptidase. Given this diagram, which of the following statements must be true? (C) (D) oplasmic Reticulum The N-terminus of this protein is in the ER lumen The mature version of this protein will span the membrane twice, with both the N- and C-terminus in the cytoplasm. Two of the answers are correct The C-terminus of this protein is in the ER lumen

Which of the following molecules may diffuse freely through a phospholipid bilayer? (select two answers) asparagine, an amino acid with a large, hydrophilic side chain alanine, an amino acid with a small, hydrophobic side-chain testosterone, a steroid hormone fructose, a monosaccharide molecular oxygen (O2)

Which of the following molecules can normally cross a phospholipid bilayer by simple diffusion? O Oxygen O Potassium ion (K+) O Methionine O Glucose

In general terms, what would you expect to be different about the permeability of a lipid bilayer made of phospholipids (modern cells) and a bilayer made of fatty acids (protocell)?

What are direct-to-consumer genetic tests? What are some of the concerns about these tests?

Explain how the chemical composition/structure of the plasma membrane allows for it to be selectively permeable. What does this information tell you about the chemical composition of an integral protein versus a peripheral protein? How do these differences allow for their different functions?