4-1 Vocab

Question 1

G Protein

Answer 1

A GTP-binding protein that relays signals from a plasma membrane signal receptor, known as a G protein-coupled receptor, to other signal transduction proteins inside the cell

Question 2

Ligand-Gated Channel

Answer 2

A transmembrane protein containing a pore that opens or closes as it changes shape in response to a signaling molecule (ligand), allowing or blocking the flow of specific ions; also called an ionotropic receptor

Question 3

Protein Kinase

Answer 3

An enzyme that transfers phosphate groups from ATP to a protein, thus phosphorylating the protein

Question 4

Integral Proteins

Answer 4

A transmembrane protein with
hydrophobic regions that extend into and often completely span the hydrophobic interior of the membrane and with hydrophilic regions in contact with the aqueous solution on one or both sides of the membrane (or lining the channel
in the case of a channel protein)

Question 5

Plasmolysis

Answer 5

A phenomenon in walled cells in which the cytoplasm shrivels and the plasma membrane pulls away from the cell wall; occurs when the cell loses water to a hypertonic environment

Question 6

Aquaporins

Answer 6

A channel protein in the plasma membrane of a plant, animal, or microorganism cell that specifically facilitates osmosis, the diffusion of free water across the membrane

Question 7

Electrogenic Pump

Answer 7

An active transport protein that generates voltage across a membrane while pumping ions

Question 8

Hormones

Answer 8

In multicellular organisms, one of many types of secreted chemicals that are formed in specialized cells, travel in body fluids, and act on specific target cells in other parts of the body, changing the target cells’ functioning. Hormones are thus important in long-distance signaling

Question 9

Transduction

Answer 9

A process in which phages (viruses) carry bacterial DNA from one bacterial cell to another. When these two cells are members of different species, transduction results in horizontal gene transfer

Question 10

Active Transport

Answer 10

The movement of a substance across a cell membrane against its concentration or electrochemical gradient, mediated by specific transport proteins and requiring an expenditure of energy

Question 11

Protein Phosphatases

Answer 11

An enzyme that removes phosphate groups from (dephosphorylates) proteins, often functioning to reverse the effect of a protein kinase

Question 12

Cyclic AMP

Answer 12

(cAMP) Cyclic adenosine monophosphate, a ring-shaped molecule made from ATP that is a common intracellular signaling molecule (second messenger) in eukaryotic cells. It is also a regulator of some bacterial operons

Question 13

Osmoregulation

Answer 13

Regulation of solute concentrations and water balance by a cell or organism

Question 14

Membrane Potential

Answer 14

The difference in electrical charge (voltage) across a cell’s plasma membrane due to the differential distribution of ions. Membrane potential affects the activity of excitable cells and the transmembrane movement of all charged substances

Question 15

G Protein-Coupled Receptor

Answer 15

(GPCR) A signal receptor protein in the plasma membrane that responds to the binding of a signaling molecule by activating a G protein. Also called a G protein-linked receptor

Question 16

Peripheral Proteins

Answer 16

A protein loosely bound to the surface of a membrane or to part of an integral protein and not embedded in the lipid bilayer

Question 17

Ligand

Answer 17

A molecule that binds specifically to another molecule, usually a larger one

Question 18

Amphipathic

Answer 18

Having both a hydrophilic region and a hydrophobic region

Question 19

Transport Proteins

Answer 19

A transmembrane protein that helps a certain substance or class of closely related substances to cross the membrane

Question 20

Sodium-Potassium Pump

Answer 20

A transport protein in the plasma membrane of animal cells that actively transports sodium out of the cell and potassium into the cell