Exam 6: Lipids, membranes, and the First Cells

Integral membrane proteins stay in membranes because of

Valine,a nonpolar amino acid,shows up in the wrong place in the hemoglobin of sickle-cell anemia,causing the disease.This is due to a genetic mutation.The result of this mutation is that hemoglobin molecules-which transport oxygen in red blood cells-stick together,causing the red blood cells to become distorted,but without having any significant effect on oxygen binding.Based on what you know about protein structure and the polarity of amino acids,predict where the mutated valine would most likely be found.

Which characteristic would be expected in the plasma membranes of a plant that can survive winters in Northern Ontario,compared to a plant growing in a warmer region?

Which of the following best describes this particular protein?

What region of a steroid is hydrophilic?

What most distinguishes lipids from other biomolecules is

Which of the following phospholipid membranes would be most permeable to glycerol?

Which of the following observations made with freeze-fracture electron microscopy provides evidence for the fluid-mosaic model of membrane structure?

What is the most important factor in explaining why osmosis occurs spontaneously?

Where would you most likely find an integral membrane protein?

If you mechanically shook a mixture of amphipathic lipids and water,what would you expect to see when the solution is observed with an electron microscope?

To determine if membrane proteins affect membrane permeability,you could isolate the proteins from the lipid components of the membrane by using detergents.Then you could separate the individual proteins and test each of them in a planar bilayer.What technique could you use to separate the proteins from one another after they have been isolated from the membrane?

Phospholipids can form all of the following structures in water except which one?

You make two sucrose solutions,one 0.5M and one of 2M and go out for lunch.When you return,you realize that you forgot to label the beakers! You remake the solutions,but give the undergrads in your lab an experiment to determine which beaker holds which solution.They fill two balloons,which are semi-permeable to water,but not to sucrose,with a 0.75M sucrose solution.One balloon is then placed in each of the unknown sucrose solution beakers.After several hours,they observe that the balloon in beaker 1 has swelled,while the balloon in beaker 2 has shriveled.This indicates that the solution in beaker 1 was ________ relative to the solution in the balloon,while beaker 2's solution was ________ relative to the solution in the balloon.