A&P1 Chapter 3 Section 2

In chemical signaling, which of the following is considered to be a second messenger? 1. Cyclic AMP 2. G protein 3. Ligand 4. Neurotransmitter

1. Cyclic AMP Chemical signaling is the process in which a ligand, the chemical messenger, binds a specific receptor and initiates a response. Ligands include most neurotransmitters (nervous system signals), hormones (endocrine system signals), and paracrines (chemicals that act locally and are rapidly destroyed)

Match the type of membrane transport with the appropriate characteristic: Secondary active transport. 1. Driven indirectly by energy stored in concentration gradients of ions 2. Random motion of a substance resulting in movement from an area of high to lower concentration 3. A passive process utilizing a protein carrier or channel 4. Movement of a substance that utilizes a carrier; energy comes directly from hydrolysis of ATP

1. Driven indirectly by energy stored in concentration gradients of ions

Correctly match the term and definition: Vesicular transport that moves substances into cells. 1. Endocytosis 2. Diffusion 3. Osmosis 4. Exocytosis

1. Endocytosis Endocytosis brings substances into the cell, typically in protein coated vesicles. Protein-coated vesicles provide the main route for endocytosis and transcytosis of bulk solids, most macromolecules, and fluids.

Which of the following pairs is a correct match? 1. Exocytosis: active membrane transport process 2. Osmosis: active membrane transport process 3. Facilitated diffusion: active membrane transport process 4. Endocytosis: passive membrane transport process

1. Exocytosis: active membrane transport process

Match the type of membrane transport with the appropriate characteristic: Primary active transport. 1. Movement of a substance that utilizes a carrier; energy comes directly from hydrolysis of ATP 2. Random motion of a substance resulting in movement from an area of high to lower concentration 3. A passive process utilizing a protein carrier or channel 4. Movement of a substance that utilizes a carrier, and has a concentration gradient as the source of energy

1. Movement of a substance that utilizes a carrier; energy comes directly from hydrolysis of ATP Primary active transport involves the movement of a substance that utilizes a carrier; energy comes directly from hydrolysis of ATP. In primary active transport, hydrolysis of ATP results in the phosphorylation of the transport protein. This step causes the protein to change its shape in such a manner that it "pumps" the bound solute across the membrane.

By which method does the following move into the cell: Movement of large particles, bacteria, or cellular debris by endocytotic vesicle 1. Phagocytosis 2. Receptor-mediated endocytosis 3. Osmosis 4. Diffusion 5. Pinocytosis

1. Phagocytosis In phagocytosis ("cell eating"), the cell engulfs some relatively large or solid material, such as a clump of bacteria, cell debris, or inanimate particles (asbestos fibers or glass, for example). When a particle binds to receptors on the cell's surface, cytoplasmic extensions called pseudopods (pseudo = false, pod = foot) form and flow around the particle.

Correctly match the term and definition: Endocytosis of a tiny quantity of extracellular fluid containing solute molecules. 1. Pinocytosis 2. Phagocytosis 3. Osmosis 4. Receptor-mediated endocytosis

1. Pinocytosis

The sodium-potassium pump helps to maintain the concentration gradients for sodium and potassium ions across the plasma membrane. Select the true statement regarding the sodium-potassium pump. 1. For each molecule of ATP used, the pump moves two negatively charged sodium ions into the cell. 2. For each molecule of ATP used, the pump moves three positively charged sodium ions out of the cell. 3. For each molecule of ATP used, the pump moves three positively charged potassium ions out of the cell. 4. For each molecule of ATP used, the pump moves two negatively charged potassium ions out of the cell.

2. For each molecule of ATP used, the pump moves three positively charged sodium ions out of the cell.

Which of the following binds to a specific receptor and initiates a response in a cell? 1. G protein 2. Ligand 3. Cyclic AMP 4. Protein kinase

2. Ligand

Crenation takes place when a cell is placed in __________. 1. a hypotonic solution 2. a hypertonic solution 3. an isotonic solution 4. a physiological saline solution

2. a hypertonic solution Hypertonic solutions have a higher concentration of nonpenetrating solutes than seen in the cell. Cells immersed in hypertonic solutions lose water and shrink, or crenate

The electrochemical gradient recognizes the effect of both electrical and concentration (chemical) forces. The electrochemical gradient applies to which of the following substances? 1. Water molecules 2. Glucose molecules 3. Sodium ions 4. Oxygen molecules

3. Sodium ions Uncharged solutes, such as oxygen, glucose, and water molecules simply diffuse down their concentration gradients. Ions are charged and therefore more complicated. The negatively and positively charged faces of the plasma membrane can help or hinder diffusion of ions driven by a concentration gradient.

Match the term with its definition: Osmotic pressure. 1. The force of a liquid pushing against something 2. A solution containing the same solutes as the cell 3. The force that solutes have to attract water 4. A solution containing more solutes than the cell 5. A solution containing fewer solutes than the cell

3. The force that solutes have to attract water In the cell, the osmotic pressure is the tendency of water to move into the cell by osmosis.

Which of the following is true with regard to membrane potential? 1. All cells in the body must maintain a constant voltage across the membrane. 2. Because the number of ions producing the membrane potential is so small that it does not change ion concentrations in any significant way, changes in extracellular Na+ will not affect membrane voltage. 3. Transient opening of gated Na+ and K+ channels in the plasma membrane is a normal means of activating neurons and muscle cells. 4. Na+ plays the key role in generating the resting membrane potential.

3. Transient opening of gated Na+ and K+ channels in the plasma membrane is a normal means of activating neurons and muscle cells.

A cell will swell, and likely burst, if it is placed in __________ solution. 1. an isotonic 2. a hypo-osmotic 3. a hypotonic 4. a hypertonic

3. a hypotonic

Cells of the body mainly use __________ for the selective endocytosis of most macromolecules. 1. fluid-phase endocytosis 2. diffusion 3. receptor-mediated endocytosis 4. pinocytosis

3. receptor-mediated endocytosis The main mechanism for the specific endocytosis and transcytosis of most macromolecules by body cells is receptor-mediated endocytosis. This exquisitely selective mechanism allows cells to concentrate material that is present only in small amounts in the extracellular fluid.

Match the term with its definition: Hypotonic solution. 1. The force that solutes have to attract water 2. A solution containing the same solutes as the cell 3. The force of a liquid pushing against something 4. A solution containing fewer solutes than the cell 5. A solution containing more solutes than the cell

4. A solution containing fewer solutes than the cell Hypotonic solutions are more dilute (contain a lower concentration of nonpenetrating solutes) than cells. Cells placed in a hypotonic solution plump up rapidly as water rushes into them

Cyanide poisoning prevents the production of ATP. If ATP were not available to drive the sodium-potassium pump, which of the following is most likely? 1. Na+ concentration inside the cell will decrease causing depolarization. 2. The voltage of the membrane will be unchanged. 3. K+ concentrations inside the cell will increase causing hyperpolarization. 4. Na+ will leak back into the cell and bring water with it causing cells to burst.

4. Na+ will leak back into the cell and bring water with it causing cells to burst. If Na+ was not continuously removed from cells, so much would accumulate intracellularly that the osmotic gradient would draw water into the cells, causing them to burst. In addition, the inability to pump sodium ions out of the cell would increase their intracellular concentration and depolarize the membrane

Which type of membrane transport process uses ATP as a source of energy? 1. Filtration 2. Simple diffusion 3. Facilitated diffusion 4. Primary active transport 5. Osmosis

4. Primary active transport Primary active transport involves the movement of a substance that utilizes a carrier; energy comes directly from hydrolysis of ATP. In primary active transport, hydrolysis of ATP results in the phosphorylation of the transport protein. This step causes the protein to change its shape in such a manner that it "pumps" the bound solute across the membrane.

Match the term with its definition: Hydrostatic pressure. 1. The force that solutes have to attract water 2. A solution containing the same solutes as the cell 3. A solution containing more solutes than the cell 4. The force of a liquid pushing against something 5. A solution containing fewer solutes than the cell

4. The force of a liquid pushing against something

Select the statement that is false regarding the resting membrane potential. 1. The membrane potential is a voltage, which is potential energy resulting from the separation of oppositely charged particles. 2. The charge separation of the resting membrane potential exists only at the membrane; the cell interior is electrically neutral. 3. In their resting state, the plasma membranes of all body cells exhibit a resting membrane potential. 4. The minus sign of the resting membrane potential indicates that the outside of the cell is negative compared to its inside.

4. The minus sign of the resting membrane potential indicates that the outside of the cell is negative compared to its inside.

Pinocytosis is a type of__________. 1. receptor-mediated exocytosis 2. facilitated diffusion 3. exocytosis 4. endocytosis

4. endocytosis Three types of endocytosis use protein-coated vesicles but differ in the type and amount of material taken up and the means of uptake. These are phagocytosis, pinocytosis, and receptor-mediated endocytosis. In pinocytosis ("cell drinking"), also called fluid-phase endocytosis, a bit of infolding plasma membrane (which begins as a protein-coated pit) surrounds a very small volume of extracellular fluid containing dissolved molecules. This droplet enters the cell and fuses with an endosome.

Proteins in the cell membrane that bind hormones and relay messages into the interior of the cell __________. 1. are known as carrier proteins 2. are known as channel proteins 3. provide cell identification 4. perform a function known as signal transduction

4. perform a function known as signal transduction Integral proteins are firmly inserted into the lipid bilayer. Some protrude from one membrane face only, but most are transmembrane proteins that span the entire membrane and protrude on both sides.

The resting membrane potential is mainly determined by __________. 1. the concentration of Na+ 2. the concentration of Cl- 3. the concentration of protein anions outside the cell 4. the concentration gradient of K+ and the differential permeability of the plasma membrane to K+ and other ions

4. the concentration gradient of K+ and the differential permeability of the plasma membrane to K+ and other ions

By which method does the following move into the cell: molecules moving against the concentration gradient? 1. Receptor-mediated endocytosis 2. Osmosis 3. Diffusion 4. Phagocytosis 5. Active transport mechanisms

5. Active transport mechanisms Like carrier-mediated facilitated diffusion, active transport requires carrier proteins that combine specifically and reversibly with the transported substances. However, facilitated diffusion always follows concentration gradients because its driving force is kinetic energy. In contrast, active transporters or solute pumps move solutes, most importantly ions, "uphill" against a concentration gradient. To do this work, cells must expend energy.

Correctly match the term and definition: The fusion of a vesicle with the plasma membrane to move substances out of the cell. 1. Endocytosis 2. Osmosis 3. Diffusion 4. Primary active transport 5. Exocytosis

5. Exocytosis