Chapter 3 Flashcards
Briefly describe the fluid mosaic model.
The fluid mosaic model states that the molecular arrangement of the plasma membrane resembles an ever-moving sea of fluid lipids containing a mosaic of many different proteins.
1) What are the three main parts of a eukaryotic cell?
D) plasma membrane, cytoplasm, nucleus
The three main components of the lipid bilayer portion of a plasma membrane are
phospholipids, cholesterol, and glycolipids
What are the nonpolar parts of phospholipids?
fatty acid tail groups
5) The polar portion of a cholesterol molecule, which forms hydrogen bonds with the polar heads of neighboring phospholipids and glycolipids, consists of a
a) –OH group
6) This type of membrane protein extends across the entire lipid bilayer of the plasma membrane touching both intracellular fluid and the extracellular fluid.
transmembrane protein
Describe five different functions of integral membrane proteins.
Some membrane proteins act as ion channels or carriers that transport substances across the membrane. Other membrane proteins act as receptors that allow the cell to respond to various types of ligands. Other membrane proteins are enzymes that catalyze specific chemical reactions. Still other membrane proteins act as linker proteins that anchor cells to neighboring structures including other cells. Lastly, some membrane proteins serve as cell identity molecules.
8) This type of membrane protein enables cells to catalyze specific chemical reactions at the inner or outer surface of their plasma membrane.
enzymes
9) Which of the following types of membrane proteins function by recognizing and binding to hormones and neurotransmitters?
receptors
10) This type of membrane protein anchors cells to neighboring cells and to protein filaments found outside or inside the cell.
linkers
11) Plasma membranes are _____, which means that some chemicals move easily through plasma membrane while other chemicals do not.
a) selectively permeable
12) Which of the following does NOT influence the rate of diffusion of a chemical across a plasma membrane?
amount of ATP available
13) Briefly describe the driving force for the movement of water across plasma membranes.
Water moves across membranes by osmosis, which is driven by solute concentration differences across the membrane. Water moves from the area of low solute concentration to the area of high solute concentrations.
14) This is a measure of a solution’s ability to change the volume of cells by altering their water content.
tonicity
15) This is the transport process by which gases, like O2 and CO2, move through a membrane.
d) simple diffusion
16) In this type of transport process, a solute (e.g. glucose) binds to a specific carrier protein on one side of the membrane. This binding induces a conformational change in the carrier protein that results in the solute moving down its concentration gradient to the other side of the membrane.
d) facilitated diffusion
17) In this transport process, the energy from hydrolysis of ATP is used to drive substances across the membrane against their own concentration gradients.
primary active transport
18) If the solute concentration is greater inside of the cell than outside the cell, water will move by osmosis
a) into the cell.
19) What transport process uses the energy stored in a Na+ or H+ concentration gradient to drive other substances across the membrane against their own concentration gradients?
secondary active transport
20) Which of the following transport processes uses vesicles that fuse with the plasma membrane to secrete materials into the extracellular fluid?
exocytosis
21) Which of the following transport process uses vesicles formed at the plasma membrane to take up extracellular substances and import them into the cell?
endocytosis
22) List the steps involved in receptor-mediated endocytosis.
The steps involved in receptor-mediated endocytosis include 1)ligand binding, 2)vesicle formation, 3)uncoating of the vesicle, 4)fusion of the vesicle with endosome, 5)recycling of receptors to the plasma membrane, and 6)degradation of the ligand in the lysosome.
23) During phagocytosis, binding of a particle to a plasma membrane receptor triggers formation of _____, which are extensions of the plasma membrane of the phagocyte that eventually surround the particle forming a phagosome.
pseudopods
