Mastering Biology ch.5

Which of the following statements correctly describe(s) the driving forces for diffusion of Na+ and K+ ions through their respective channels? Select all that apply.

- The diffusion of Na+ ions into the cell is facilitated by the Na+ concentration gradient across the plasma membrane; - The diffusion of K+ ions out of the cell is impeded by the electrical gradient across the plasma membrane; - The electrochemical gradient is larger for Na+ than for K+.

Which of these is a signal molecule?

A

Which of these is a receptor molecule?

B

Which component in the figure is a peripheral protein?

D

Which of the following is a characteristic feature of a carrier protein in a plasma membrane?

It exhibits a specificity for a particular type of molecule.

What are the functions of signal transduction pathways?

Signal transduction pathways amplify the effect of a signal molecule; Signal transduction pathways convert a signal on a cell's surface to a specific cellular response; Signal transduction pathways allow different types of cells to respond differently to the same signal molecule

In facilitated diffusion, what is the role of the transport protein?

Transport proteins provide a hydrophilic route for the solute to cross the membrane

The primary function of kinases in signal transduction is to

activate protein kinases or other relay molecules in a series

Orange dye moves independently of purple dye. *never, always, only before equilibrium is reached, or only at equilibrium*

always

An integral membrane protein would have to be

amphipathic, with at least one hydrophobic region

Sort the phrases into the appropriate bins depending on whether they are true only for channels, true only for carrier proteins, or true for both channels and carriers. - are integral membrane proteins

both channels and carriers

Sort the phrases into the appropriate bins depending on whether they are true only for channels, true only for carrier proteins, or true for both channels and carriers. - provide a hydrophilic path across the membrane

both channels and carriers

Sort the phrases into the appropriate bins depending on whether they are true only for channels, true only for carrier proteins, or true for both channels and carriers. - transport solutes down a concentration or electrochemical gradient

both channels and carriers

Sort the phrases into the appropriate bins depending on whether they describe exocytosis, endocytosis, or both. - requires cellular energy

both endocytosis and exocytosis

Sort the phrases into the appropriate bins depending on whether they describe exocytosis, endocytosis, or both. - transported substances never physically cross the plasma membrane

both endocytosis and exocytosis

Which of the following molecules can cross the lipid bilayer of a membrane directly, without a transport protein or other mechanism? Select all that apply.

carbon dioxide, lipids, oxygen, water

Sort the phrases into the appropriate bins depending on whether they describe exocytosis, endocytosis, or both. - decreases the surface area of the plasma membrane

endocytosis

Sort the phrases into the appropriate bins depending on whether they describe exocytosis, endocytosis, or both. - forms vesicles from inward folding of the plasma membrane

endocytosis

Sort the phrases into the appropriate bins depending on whether they describe exocytosis, endocytosis, or both. - increases the surface area of the plasma membrane

exocytosis

Sort the phrases into the appropriate bins depending on whether they describe exocytosis, endocytosis, or both. - requires fusion of vesicles with the plasma membrane

exocytosis

Sort the phrases into the appropriate bins depending on whether they describe exocytosis, endocytosis, or both. - secretes large molecules out of the cell

exocytosis

Celery stalks that are immersed in freshwater for several hours become turgid (stiff). Celery stalks left in a 0.15 M salt solution become flaccid (limp). From this we can deduce that the fresh water is _________________ and the salt solution is ______________ to the cells of the celery stalks.

hypotonic; hypertonic

A signal molecule is also known as a(n) _____.

ligand

Which of the following membrane activities requires energy from ATP hydrolysis?

movement of sodium ions from a lower concentration in a mammalian cell to a higher concentration in the extracellular fluid

Purple dye moves only from side B to side A. *never, always, only before equilibrium is reached, or only at equilibrium*

never

There is no net movement of purple dye. *never, always, only before equilibrium is reached, or only at equilibrium*

only at equilibrium

Concentration gradients exist that drive diffusion of both dyes. *never, always, only before equilibrium is reached, or only at equilibrium*

only before equilibrium is reached

There is net movement of orange dye from side A to side B. *never, always, only before equilibrium is reached, or only at equilibrium*

only before equilibrium is reached

Sort the phrases into the appropriate bins depending on whether they are true only for channels, true only for carrier proteins, or true for both channels and carriers. - transport primarily small polar organic molecules

only carriers

Sort the phrases into the appropriate bins depending on whether they are true only for channels, true only for carrier proteins, or true for both channels and carriers. - undergo a change in shape to transport solutes across the membrane

only carriers

Sort the phrases into the appropriate bins depending on whether they are true only for channels, true only for carrier proteins, or true for both channels and carriers. - allow water molecules and small ions to flow quickly across the membrane

only channels

Sort the phrases into the appropriate bins depending on whether they are true only for channels, true only for carrier proteins, or true for both channels and carriers. - provide a continuous path across the membrane

only channels

The primary structural components of the cell membrane are

phospholipids and proteins

A signal transduction pathway is initiated when a _____ binds to a receptor.

signal molecule

What kinds of molecules pass through a cell membrane most easily?

small hydrophobic

Active transport by the sodium-potassium pump follows this cycle. *name the step* Three Na+ ions from the cytosol bind to the pump.

step 1

Active transport by the sodium-potassium pump follows this cycle. *name the step* The binding of Na+ stimulates the phosphorylation of the pump protein by ATP.

step 2

Active transport by the sodium-potassium pump follows this cycle. *name the step* Phosphorylation causes a conformational change in the pump that moves the three Na+ ions against their concentration gradient and releases them outside the cell.

step 3

Active transport by the sodium-potassium pump follows this cycle. *name the step* The release of the Na+ ions permits two K+ ions from outside the cell to bind to the pump, and the phosphate group is released.

step 4

Active transport by the sodium-potassium pump follows this cycle. *name the step* Release of the phosphate group causes another conformational change in the pump.

step 5

Active transport by the sodium-potassium pump follows this cycle. *name the step* The conformational change in the pump moves the two K+ ions against their concentration gradient and releases them into the cytosol.

step 6

Which of these is the second of the three stages of cell signaling?

transduction

Which of the following best describes the structure of a biological membrane?

two layers of phospholipids with proteins either crossing the layers or on the surface of the layers