Cell Structure and Function: Protein Sorting

Question 1

protein sorting

Answer 1

process by which a cell transports and directs proteins to specific organelles or secretion outside the cell

Question 2

(ER) signal sequence or signal peptide

Answer 2

short amino acid sequence which targets nascent proteins to the endoplasmic reticulum and secretion pathway

Question 3

fluid mosaic model of membrane structure

Answer 3

a model that describes the phospholipid bilayer as fluid and proposes that integral membrane proteins float freely in the lipid bilayer

Question 4

cell secretion

Answer 4

release of proteins or other cellular products into the extracellular space

Question 5

exocytosis

Answer 5

process by which secretory vesicles fuse with and become part of the plasma membrane, releasing vesicular contents outside the cell

Question 6

endocytosis

Answer 6

process by which vesicles are internalized from the plasma membrane; often used to absorb or ingest molecular contents into the cell

Question 7

integral membrane protein

Answer 7

protein that is permanently embedded in the cell membrane

Question 8

transmembrane protein

Answer 8

integral membrane protein that spans the entire width of a cell membrane

Question 9

osmosis

Answer 9

diffusion of water across a selectively permeable membrane due to solute differences on either side of the membrane

Question 10

isotonic solutions

Answer 10

solutions separated by a membrane and containing an equal concentration of non-permeating solutes

Question 11

hypotonic solution

Answer 11

solution with a lower concentration of non-permeating solutes than that of the solution on the other side of a membrane

Question 12

hypertonic solution

Answer 12

solution with a higher concentration of non-permeating solutes than that of the solution on the other side of a membrane

Question 13

facilitated diffusion (passive transport)

Answer 13

movement of molecules across a membrane via transport proteins without energy from ATP hydrolysis

Question 14

active transport

Answer 14

movement of molecules across a membrane, typically against a concentration gradient, by transport proteins that require energy from ATP hydrolysis; this energy requirement can be direct (primary active transport) or indirect (secondary active transport)

Question 15

electrochemical gradient

Answer 15

combined electrical and chemical (diffusion) forces acting on an ion between two sides of a cell membrane

Question 16

membrane potential

Answer 16

electrical potential or voltage between the two sides of the plasma membrane

Question 17

aquaporin

Answer 17

transport protein for the facilitated diffusion of water through a cell membrane

Question 18

ion channel

Answer 18

transport protein for the facilitated diffusion of ion(s) through a cell membrane

Question 19

ion pump

Answer 19

protein that moves ion(s) through a cell membrane by primary active transport

Question 20

cotransporter

Answer 20

protein that moves two or more molecules through a cell membrane by secondary active transport