Biology 1001 Exam 2 (LSU-Hrincevich) studyguide

CHAPTER 5: Within the fluid mosaic of a plasma membrane, what is the role of transport and channel proteins? - They permit salts and sugars to move through the plasma membrane. CHAPTER 5: If red blood cells are taken from the body and placed in a hypertonic solution, what happens to the cells? - The cells shrivel up because water leaves them. CHAPTER 5: Plasma membranes are BEST described as a what? - single layer of phospholipids with tails pointed toward the inside of the cell. CHAPTER 5: Osmosis moves water from a region of what to what? - low concentration of dissolved material to a region of high concentration. CHAPTER 5: More than half a century ago, two cell biologists published details of their research involving isolated membrane vesicles from chloroplasts. Normally, the fluid inside these vesicles is near neutral. In an experiment, these membrane vesicles were soaked in an acidic solution (pH 4) until the inside of the vesicle also became pH 4. Based on the details provided in this scenario, by what mechanism could hydrogen ions have crossed the vesicle membrane, and what do you think happened at - Facilitated diffusion; hydrogen ions moved into the vesicle through a channel. CHAPTER 5: Suppose that plasma membranes were single layers of phospholipids with heads facing the external environment. The interior of this hypothetical cell would have to be what? - hydrophobic and nonpolar. CHAPTER 5: The cytoplasm of a certain cell, such as a neuron, already has a high concentration of potassium ions. How can potassium ions continue to enter the cell? - active transport CHAPTER 5: The blood plasma of a man who drinks saltwater will become ________ to his red blood cells, whereas the red blood cells will be ________ to the blood plasma. Which statement below correctly completes the statement? - hypertonic; hypotonic CHAPTER 5: Which of the following types of membrane proteins are responsible for conveying external messages such as those sent by a hormone signal? - receptor proteins CHAPTER 5: The hydrophobic tails of a phospholipid bilayer are oriented toward the what? - interior of the plasma membrane (i.e., toward one another).