Chapter 15

Question 1

autophagy

Answer 1

Mechanism by which a cell “eats itself,” digesting molecules
and organelles that are damaged or obsolete.

Question 2

clathrin

Answer 2

Protein that makes up the coat of a type of transport vesicle
that buds from either the Golgi apparatus (on the outward
secretory pathway) or from the plasma membrane (on the
inward endocytic pathway).

Question 3

coated vesicle

Answer 3

Small membrane-enclosed sac that wears a
distinctive layer of proteins on its cytosolic
surface. It is formed by pinching-off of a
protein-coated region of cell membrane.

Question 4

endocytosis

Answer 4

Process by which cells take in materials through an
invagination of the plasma membrane, which surrounds
the ingested material in a membrane-enclosed vesicle. (See
also pinocytosis and phagocytosis.)

Question 5

endomembrane system

Answer 5

Interconnected network of membrane-enclosed organelles
in a eukaryotic cell; includes the endoplasmic reticulum,
Golgi apparatus, lysosomes, peroxisomes, and endosomes.

Question 6

endoplasmic reticulum

Answer 6

Labyrinthine membrane-enclosed
compartment in the cytoplasm of
eukaryotic cells where lipids and
proteins are made.

Question 7

endosome

Answer 7

Membrane-enclosed compartment of a eukaryotic cell
through which material ingested by endocytosis passes on
its way to lysosomes.

Question 8

exocytosis

Answer 8

Process by which most molecules are secreted from
a eukaryotic cell. These molecules are packaged in
membrane-enclosed vesicles that fuse with the plasma
membrane, releasing their contents to the outside.

Question 9

lysosome

Answer 9

Membrane-enclosed organelle that breaks down worn-out
proteins and organelles and other waste materials, as well
as molecules taken up by endocytosis; contains digestive
enzymes that are typically most active at the acid pH found
inside these organelles.

Question 10

membrane-enclosed organelle

Answer 10

Any organelle in a eukaryotic cell that is surrounded by a
lipid bilayer—for example, the endoplasmic reticulum, Golgi
apparatus, and lysosome.

Question 11

nuclear envelope

Answer 11

Double membrane surrounding the nucleus. Consists of

outer and inner membranes, perforated by nuclear pores.

Question 12

nuclear pore

Answer 12

Channel through which selected large
molecules move between the nucleus
and the cytoplasm.

Question 13

peroxisome

Answer 13

Small membrane-enclosed organelle that contains enzymes

that degrade lipids and destroy toxins.

Question 14

phagocytic cell

Answer 14

A cell such as a macrophage or neutrophil that is specialized
to take up particles and microorganisms by phagocytosis.

Question 15

phagocytosis

Answer 15

The process by which particulate material is engulfed
(“eaten”) by a cell. Prominent in predatory cells, such as
Amoeba proteus, and in cells of the vertebrate immune
system, such as macrophages.

Question 16

pinocytosis

Answer 16

Type of endocytosis in which soluble materials are taken
up from the environment and incorporated into vesicles for
digestion. (Literally, “cell drinking.”)

Question 17

Rab protein

Answer 17

One of a family of small GTP-binding proteins present on
the surfaces of transport vesicles and organelles that serves as a molecular marker to help ensure that transport vesicles
fuse only with the correct membrane.

Question 18

receptor-mediated endocytosis

Answer 18

Mechanism of selective uptake of material by animal cells
in which a macromolecule binds to a receptor in the plasma
membrane and enters the cell in a clathrin-coated vesicle

Question 19

rough endoplasmic reticulum

Answer 19

Region of the endoplasmic reticulum
associated with ribosomes and involved in
the synthesis of secreted and membranebound proteins.

Question 20

secretion

Answer 20

Membrane-enclosed organelle in which molecules destined

for secretion are stored prior to release.

Question 21

secretory vesicle

Answer 21

Membrane-enclosed organelle in which molecules destined

for secretion are stored prior to release.

Question 22

signal sequence

Answer 22

Amino acid sequence that directs a protein to a specific

location in the cell, such as the nucleus or mitochondria.

Question 23

SNARE

Answer 23

One of a family of membrane proteins responsible for the
selective fusion of vesicles with a target membrane inside
the cell.

Question 24

tethering protein

Answer 24

Filamentous transmembrane protein involved in the

docking of transport vesicles to target membranes.

Question 25

transport vesicle

Answer 25

Membrane vesicle that carries proteins from one
intracellular compartment to another—for example, from
the endoplasmic reticulum to the Golgi apparatus.

Question 26

unfolded protein response (UPR)

Answer 26

Molecular program triggered by the accumulation of
misfolded proteins in the endoplasmic reticulum. Allows
cells to expand the endoplasmic reticulum and produce
more of the molecular machinery needed to restore proper
protein folding and processing.

Question 27

vesicular transport

Answer 27

Movement of material between organelles in the eukaryotic

cell via membrane-enclosed vesicles.