Chapter 5 VOCAB

Question 1

integral membrane proteins

Answer 1

Proteins that are at least partially embedded in the plasma membrane.

Question 2

ligand

Answer 2

Any molecule that binds to a receptor site of another (usually larger) molecule.

Question 3

G protein–linked receptors

Answer 3

A class of receptors that change configuration upon ligand binding such that a G protein binding site is exposed on the cytoplasmic domain of the receptor, initiating a signal transduction pathway.

Question 4

hypertonic

Answer 4

Having a greater solute concentration. Said of one solution compared to another.

Question 5

G protein

Answer 5

membrane protein involved in signal transduction; characterized by binding GDP or GTP.

Question 6

secondary active transport

Answer 6

A form of active transport that does not use ATP as an energy source; rather, transport is coupled to ion diffusion down a concentration gradient established by primary active transport.

Question 7

peripheral membrane proteins

Answer 7

Proteins associated with but not embedded within the plasma membrane.

Question 8

receptor-mediated endocytosis

Answer 8

Endocytosis initiated by macromolecular binding to a specific membrane receptor.

Question 9

passive transport

Answer 9

Diffusion across a membrane; may or may not require a channel or carrier protein.

Question 10

cAMP (cyclic AMP)

Answer 10

A compound formed from ATP that acts as a second messenger.

Question 11

aquaporin

Answer 11

A transport protein in plant and animal cell membranes through which water passes in osmosis.

Question 12

transmembrane protein

Answer 12

An integral membrane protein that spans the phospholipid bilayer.

Question 13

paracrine

Answer 13

Pertaining to a chemical signal, such as a hormone, that acts locally, near the site of its secretion.

Question 14

selective permeability

Answer 14

Allowing certain substances to pass through while other substances are excluded; a characteristic of membranes.

Question 15

glycolipid

Answer 15

A lipid to which sugars are attached.

Question 16

simple diffusion

Answer 16

Diffusion that doesn’t involve a direct input of energy or assistance by carrier proteins

Question 17

sodium–potassium pump (Na+–K+ pump)

Answer 17

Antiporter responsible for primary active transport; it pumps sodium ions out of the cell and potassium ions into the cell, both against their concentration gradients

Question 18

gated channel

Answer 18

A membrane protein that changes its three-dimensional shape, and therefore its ion conductance, in response to a stimulus. When open, it allows specific ions to move across the membrane.

Question 19

channel protein

Answer 19

An integral membrane protein that forms an aqueous passageway across the membrane in which it is inserted and through which specific solutes may pass.

Question 20

carrier protein

Answer 20

In facilitated diffusion, a membrane protein that binds a specific molecule and transports it through the membrane.

Question 21

endocytosis

Answer 21

A process by which liquids or solid particles are taken up by a cell through invagination of the plasma membrane.

Question 22

autocrine

Answer 22

A chemical signal that binds to and affects the cell that makes it.

Question 23

glycoprotein

Answer 23

A protein to which sugars are attached.

Question 24

phagocytosis

Answer 24

Endocytosis by a cell of another cell or large particle.

Question 25

turgor pressure

Answer 25

The hydrostatic pressure of an enclosed solution in excess of the surrounding atmospheric pressure.

Question 26

facilitated diffusion

Answer 26

Passive movement through a membrane involving a specific carrier protein; does not proceed against a concentration gradient.

Question 27

receptor protein

Answer 27

A protein that can bind to a specific molecule, or detect a specific stimulus, within the cell or in the cell’s external environment.

Question 28

osmosis

Answer 28

Movement of water across a differentially permeable membrane, from one region to another region where the water potential is more negative.

Question 29

protein kinase

Answer 29

An enzyme that catalyzes the addition of a phosphate group from ATP to a target protein.

Question 30

hypotonic

Answer 30

Having a lesser solute concentration. Said of one solution compared to another.

Question 31

ion channel

Answer 31

An integral membrane protein that allows ions to diffuse across the membrane in which it is embedded.

Question 32

active transport

Answer 32

The energy-dependent transport of a substance across a biological membrane against a concentration gradient—that is, from a region of low concentration (of that substance) to one of high concentration.

Question 33

signal transduction pathway

Answer 33

The series of biochemical steps whereby a stimulus to a cell (such as a hormone or neurotransmitter binding to a receptor) is translated into a response of the cell.

Question 34

pinocytosis

Answer 34

Endocytosis by a cell of liquid containing dissolved substances.

Question 35

exocytosis

Answer 35

A process by which a vesicle within a cell fuses with the plasma membrane and releases its contents to the outside.

Question 36

allosteric regulation

Answer 36

Regulation of the activity of a protein (usually an enzyme) by the binding of an effector molecule to a site other than the active site.

Question 37

primary active transport

Answer 37

Active transport in which ATP is hydrolyzed, yielding the energy required to transport an ion or molecule against its concentration gradient

Question 38

hormone

Answer 38

A chemical signal produced in minute amounts at one site in a multicellular organism and transported to another site where it acts on target cells.

Question 39

diffusion

Answer 39

Random movement of molecules or other particles, resulting in even distribution of the particles when no barriers are present.

Question 40

fluid mosaic model

Answer 40

A molecular model for the structure of biological membranes consisting of a fluid phospholipid bilayer in which suspended proteins are free to move in the plane of the bilayer.