Week 3: Membrane Transport

Which component of the plasma membrane might allow the body to recognize cells as "self" (its own) or "non-self" (foreign)?

Carbohydrate

Which of the following is not required for osmosis to occur? -selectively permeable membrane -cellular energy -water -concentration gradient

cellular energy

A vesicle fuses with the plasma membrane and releases its contents to the extracellular fluid. This statement describes _____.

exocytosis

Which of the following is not a passive process? -facilitated diffusion of glucose -Na+/K+ pump -oxygen diffusion -osmosis

Na+/K+ pump

The majority of water molecules moving across plasma membranes by osmosis do so via a process that is most similar to ____.

facilitated diffusion

Which of the following is not a major function of proteins in the cell membrane? -acting as receptors -forming channels -anchoring cells to other structures -forming the entire glycocalyx

forming the entire glycocalyx

In general, to maintain homeostasis the relationship between our intracellular and extracellular fluids should be which of the following?

isotonic to each other

Some white blood cells defend the body from infectious bacteria by the process of __________.

phagocytosis Macrophages and certain white blood cells are called phagocytic cells because their primary function is to ingest foreign substances or bacteria via phagocytosis.

Which of the following is most likely to move through the cell membrane by facilitated diffusion? -CO2 -O2 -small lipids -Na+

Na+

Which of the following processes requires ATP?

exocytosis Exocytosis is a form of vesicular transport. All vesicular transport processes are active processes that require ATP.

Some transport processes use transport proteins in the plasma membrane, but do not require ATP. This type of transport is known as _____.

facilitated diffusion

Which of the following generated osmotic pressure?

sodium chloride, glucose and albumin generated osmotic pressure.

Which of the following best describes the driving force behind secondary active transport?

the concentration gradient produced by primary active transport drives the transport of other materials For example, the sodium-potassium ATPase pump creates a high concentration of sodium in the extracellular fluid. This sodium concentration gradient provides the energy to bring other molecules such as glucose into the cell via a symport transport protein.

Which of the following is a characteristic of the cell membrane?

semipermeable

Which of the following solutions contains the most solute?

hypertonic

A not very well-studied A&P student heard about a phenomenon called water intoxication and thought it sounded fun so she decided to try it. She consumed a large amount of water in a short time (Don't try this—water intoxication is often fatal.). Instead of feeling drunk, she felt nauseated, developed a severe headache, began to get confused, and then became unconscious. Her much more prepared A&P student roommate quickly realized the problem and called an ambulance. When the roommate told the Emergency Department doctor what had happened, the doctor quickly began administering IV (intravenous) fluids.Based on this information and your understanding of osmosis and tonicity, what type of IV fluid is the doctor likely administering to try to save the life of the student suffering from water intoxication?

hypertonic IV fluid Excellent! Her blood is very hypotonic, causing water to move from her blood into her cells, which caused her brain to swell. Raising the blood tonicity with hypertonic IV fluid should hopefully draw the excess water back out of the cells.

The sodium-potassium pump uses ATP to move sodium and potassium ions across the plasma membrane. This statement describes _____.

primary active transport

Substances can move across the plasma membrane in two different ways—actively or passively. This activity will help you determine whether transport mechanisms actively or passively move substances across the membrane. Sort the following types of membrane transport mechanisms into active or passive processes.

Active Process: Secondary active transport, Primary active transport, Endocytosis, Exocytosis Passive Process: Simple diffusion, Facilitated diffusion, Osmosis

Which of the following is the best situation for maintaining homeostasis?

Extracellular fluid should be isotonic to intracellular fluid.

What is the basic difference between simple diffusion and facilitated diffusion across a cell membrane?

In facilitated diffusion, molecules only move with the aid of a protein in the membrane.

If a person goes to the hospital for surgery and requires IV (intravenous) fluids, which of the following should you expect?

The IV fluid should be isotonic to the patient's blood.

If a person is severely dehydrated, their extracellular fluids will become hypertonic to the intracellular fluid. What do you predict will happen to the person's cells?

The cells will lose water and shrink.

With the experimental conditions set at 10 mM glucose and 9 mM albumin, and the 200 MWCO membrane in place, which of the following is true?

The net movement of water is toward the albumin.

Which of the following accurately describes a difference between simple and facilitated diffusion?

The rate of facilitated diffusion may be controlled by altering the activity or number of transport proteins, but the rate of simple diffusion cannot be controlled. Activating more channels or carrier proteins would increase the rate of facilitated diffusion, and inactivating them would decrease the rate. Simple diffusion relies on lipid solubility and membrane permeability, which are not as easily changed.

Which of the following would result in NO change in osmotic pressure across a membrane? -The solutes can diffuse through the pores and the concentration of solutes is the same on both sides of the membrane. -The concentration of solutes is the same on both sides of the membrane. -Water is moving with its concentration gradient. -The solutes can diffuse through the pores.

The solutes can diffuse through the pores and the concentration of solutes is the same on both sides of the membrane.

A primary active transport process is one in which __________.

molecules move through transport proteins that have been activated by ATP

Which of the following best explains diffusion?

movement of molecules from an area of high concentration to an area of low concentration

What part of a cell membrane is usually in contact with the interstitial fluid?

phosphate heads of phospholipids

Which of the following is the main component of the cell membrane?

phospholipids

Which of the following is least likely to increase the rate of diffusion? -higher concentration of molecules -small molecule size -small concentration gradient -high temperature

small concentration gradient

In this course, you will learn about hormones and their effects on cells. Certain hormones bind to receptors at the plasma membrane to "deliver" their message to the cell. What function of the plasma membrane is this? -Physical barrier -Communication -Selectively permeable -Cell-to-cell recognition

Communication

In this illustration, the three compartments are separated by semipermeable membranes. The red balls represent solutes, and the lightly shaded area represents water. Which of the following is a true statement?

Solution B is hypotonic to solution A, but hypertonic to solution C.

A cell is immersed in a beaker of solution. The cell membrane is permeable to water but impermeable to solutes. If the intracellular concentration is 10 mM and the solution is 20 mM, which of the following is true?

The cell will shrink