TEST 1: Chapter 3 -- Movement across the Cell Membrane

What is crenation, and which type of solution will cause it?

Crenation is the shriveling of Red Blood Cells (RBCs), and is caused by hypertonic solutions.

Facilitated diffusion requires which of the following? A. equilibrium B. large molecules C. a protein channel D. input of energy

C. a protein channel No energy is required because this is diffusion, a passive process.

Where is the energy stored in the ATP molecule?

Mostly in the last Phosphate bond

Which type of vesicular transport involves the formation of pseudopodia?

Phagocytosis

The net flow of water across a selectively permeable membrane in response to solute concentration differences is called ________________.

osmosis

How does temperature influence the diffusion rate of substances?

↑ Temperature = ↑ Rate of Diffusion [Remember that diffusion happens because molecules are constantly moving and bumping into each other. Heat increases movement of molecules, and therefore the rate of diffusion will increase]

Osmosis specifically refers to the diffusion of ___________ across a selectively permeable membrane

water

A solution that does NOT cause an osmotic flow (i.e., there is no water moving across the membrane) is said to be _______________?

isotonic

How does the the charge (electrical force) of an ion or molecule influence its diffusion rate?

Charged ions (such as Na+, Cl-, K+) or charged molecules are attracted to their polar opposite, allowing diffusion to occur at different speeds for different ions. They're also repelled by like charges.

What's the term for the passive process in which there is random motion and collision of substances, resulting in their net movement away from an area of greater concentration to lesser concentration?

Diffusion

What are the 2 types of carrier-mediated transport mechanisms that we studied? (note set p31)

Facilitated Diffusion (moves substances WITH the concentration gradient) Active Transport (moves substances AGAINST the concentration gradient using energy from ATP)

What is hemolysis? And which type of solution will cause it?

Hemolysis is the rupture of Red Blood Cells (RBC), and is caused by hypotonic solutions. If the solution outside of the RBC is hypotonic (has less solute), water will flow into the cell (water follows solutes), and eventually the cell will rupture (if the solute concentration gradient is extreme enough)

What type of pressure opposes osmotic pressure, and can prevent the movement of water across a membrane?

Hydrostatic Pressure. This is a PUSHING pressure--think of the cracked glass, and the pressure of the water pushes drops through the crack.

What are the 2 types of proteins associated with the cell membrane?

Intergral proteins -- go all the way through the cell membrane (embedded) Peripheral proteins -- attached to surface of cell membrane

What does a substance have to do to become part of the body's internal environment? [Mr. Wood discussed this on page 22 of note set--Internal vs External environment]

Pass through at least one cell membrane

What is the name of the reaction in which a phosphate group is added to ADP?

Phosphorylation Reaction ADP + P [+energy] -----> ATP

Differentiate between SOLUTE and SOLVENT

SOLUTE = the molecules from the substance that has been dissolved SOLVENT = the substance doing the dissolving; in the body, water is always the solvent

Sodium (Na+) and Potassium (K+) are important ions to a cell. Answer the following questions: What are the relative concentrations of each on either side of the cell membrane? What mechanisms exist for them to move across the membrane?

Sodium - higher concentration OUTSIDE the cell membrane Potassium - Higher concentration INSIDE the cell. --->Na+ & K+ both diffuse through their leak channels WITH (or down) their concentration gradients, i.e., higher to lower concentration: ---------------> Na+ diffuses into the cell, and ---------------> K+ diffuses out --->Active Transport (using ATP) is used by the cell to PUMP these ions AGAINST their gradients via the sodium/potassium pump: ---------------> 3 Na+ out for every 2 K+ pumped in.

How does the concentration gradient influence the rate of diffusion?

The STEEPER the concentration gradient, the FASTER the rate of diffusion.

How does the distance of a molecule from the cell membrane influence the diffusion rate of that molecule?

The shorter the distance from the membrane, the faster the diffusion rate.

True or False? The cell cannot directly control or regulate everything that crosses it's plasma (cell) membrane.

True Some materials may pass through the cell membrane via diffusion or osmosis, and the cell cannot directly control or regulate this passive movement. (note set p29)

True or False? The processes of endocytosis and exocytosis require ATP.

True. These are ACTIVE processes, and require energy.

When does the cell need to use ATP to move a substance across the cell membrane?

When the cell wants to move a substance AGAINST THE CONCENTRATION GRADIENT, ATP is required.

If nothing can get through the cell membrane, we say that the membrane is __________. a. selectively permeable b. impermeable c. permeable d. unhospitable

b. impermeable

If the sodium concentration outside the cell is higher than the sodium concentration in the cytosol, and the cell wants to move sodium out, what type of transport would be used? a. Facilitated diffusion b. Osmosis c. Active Transport d. Diffusion through a channel protein

c. Active Transport [If something is moved AGAINST it's concentration gradient, it must used energy (ATP), and therefore it's Active Transport]

Endocytosis of large particles, such as a bacterium, is called ____________. a. exocytosis b. bacteriocytosis c. phagocytosis

c. phagocytosis ("cell eating")

The formation of vesicles filled with extracellular fluid is called ____________ , and is a form of vesicular transport called _____________. a. hydrocytosis; endocytosis b. pinocytosis; exocytosis c. pinocytosis; endocytosis d. phagocytosis; endocytosis e. phagocytosis; exocytosis

c. pinocytosis ("cell drinking"); endocytosis (coming IN) The key to this question is that the vesicle is filled with EXTRAcellular FLUID, so we know it's coming in from outside the cell, and therefore it's a form of endocytosis.

What type of permeability describes the cell membrane? a. impermeable b. permeable c. selectively permeable

c. selectively permeable

What is the term for the difference between areas of high and low concentration of a substance?

concentration gradient

Diffusion will continue until there is an equal space between particles of the substance; a condition called _______________. (note set p29)

equilibruim

A solution that causes water to move out of the cell is said to be _______________?

hypertonic [Water follows solute. If water is moving out of the cell, that means the outside of the cell must have more solute, making it hypertonic]

A solution that causes water to move into the cell is said to be _______________?

hypotonic [Remember that water follows solute. If water is moving into the cell, that means the outside of the cell must have less solute, making it hypotonic]

What is the term used for the pressure with which a solute pulls water across a selectively permeable membrane?

osmotic pressure--remember, this is a PULLING pressure, and the more solute the higher the osmotic pressure.

Describe the 3 types of vesicular transport

As the question states, all processes involve vesicle formation: Pinocytosis: intake (endocytosis) of fluid = "cell drinking" Phagocytosis: intake (endocytosis) of large particles, such as bacteria, which is then digested with enzymes from lysosomes = "cell eating" Exocytosis: moving substances out of the cell via a vesicle; the cell uses exocytosis to secrete proteins & remove waste products from the cytoplasm

Describe a simple phospholipid molecule.

Hydrophilic (water-loving) head Hydrophobic tail

Name the 3 basic types of passive transport, and distinguish between each.

Remember: All passive transport is the movement of molecules from a greater concentration to lesser concentration, only the mechanisms change. 1) SIMPLE DIFFUSION: movement of a substance from an area of greater concentration to an area of lesser concentration. 2) OSMOSIS: movement of WATER through a SELECTIVELY PERMEABLE MEMBRANE; moves toward the area of more solute (dissolved substances), [which means that the water is moving from a greater concentration (of water) to a lesser concentration (of water).] 3) FACILITATED DIFFUSION: A carrier protein in the cell membrane moves larger molecules, such as sugar, through the membrane down the concentration gradient of sugar, i.e., from an area of higher concentration to lower. REMEMBER: No ATP is used in passive transport!

How does the size of a molecule influence the diffusion rate of that molecule across the cell membrane?

Smaller Size = Increased Rate of Diffusion [Smaller molecules and ions diffuse across the cell membrane more rapidly than do larger molecules such as sugars or proteins.]

What are the 3 characteristics of OSMOSIS?

1) Diffusion of WATER molecules moving across a SELECTIVELY PERMEABLE MEMBRANE 2) Osmosis occurs across selectively permeable membrane that ALLOWS WATER THROUGH, but NOT SOLUTES. 3) WATER FOLLOWS SOLUTES, and will move across a membrane towards a solution that has the highest concentration of solute, that is, where there is less water.

What are the 2 paths an ion or molecule can take when passively diffusing across the plasma membrane? Give examples of types of molecules for each path. (This question comes from the note set, p. 29, where he says to study figure 3-15 in the text)

1) Through the PHOSPHOLIPID BILAYER part of the plasma (cell) membrane: Only lipid soluble molecules, dissolved gases (O2 & CO2), and small nonpolar (not charged) molecules. 2) Through a CHANNEL PROTEIN: Larger molecules, water-soluble molecules (i.e., not lipid soluble), and ions (which are are charged) must diffuse through a channel protein.

When molecules diffuse through a membrane, they tend to do which of the following? A. spread out until there is no longer a concentration gradient across the membrane B. move against the concentration gradient C. move until they reach equilibrium and then stop moving D. move until they have all passed to the other side of the membrane

A is the correct answer. Molecules spread out until there is no longer a concentration gradient across the membrane. Explanation: The question tells us that the molecules diffuse, and we know diffusion is passive movement from an area of greater concentration to less concentration [in other words, down it's concentration gradient...not against it], so "B" is wrong Also, molecules never stop moving, so "C" is wrong. And, "D" is wrong. Although molecules continue to move randomly, the general movement down a concentration gradient stops when there is an equal number of molecules on either side of the membrane, which means the gradient no longer exists. There is no net movement to the other side.

Fill in the blank with RARELY, ALWAYS, or USUALLY: Substances ________________ move passively from areas of high concentration to low concentration. (note set p29)

ALWAYS

The basic components of the cell membrane (that we've learned so far) include: (choose the best answer) A. Phospholipid double layer and proteins B. Phospholipid bilayer, integral proteins, peripheral proteins, and cholesterol C. Phospholipid bilayer, integral proteins, peripheral proteins, and channels made from starch molecules

B. Phospholipid bilayer, integral proteins, peripheral proteins, and cholesterol

The movement of O2 (oxygen) from the alveoli in the lungs to the capillary is an example of ________________.

Diffusion The concentration of O2 in the alveoli is much higher than the O2 concentration in the capillaries around the alveoli, so the O2 moves DOWN ITS CONCENTRATION GRADIENT and moves into the capillaries. (FYI: gases like O2 and CO2 easily diffuse through cell membranes)