CELL ORGANELLE

Question 1

______ is the process by which cells of an embryo become specialized structurally to augment specific cytoplasmic activities for functions at the level of tissues and organs.

Answer 1

Cell differentiation

Question 2

______ are metabolically active structures or complexes, with or without membranes, in the cytoplasm of eukaryotic cells.

Answer 2

Organelles

Question 3

The ______ (______ or ______) is the lipid bilayer with embedded proteins that surrounds a cell and is seen only with the TEM.

Answer 3

plasma membrane, cell membrane, plasmalemma

Question 4

Plasma Membrane

The ______ forms from amphipathic ______, stabilized by ______, and contains many ______ (______) proteins and many ______ proteins on its cytoplasmic surface.

Answer 4

lipid bilayer, phospholipids, cholesterol, embedded, integral, peripheral

Question 5

Plasma Membrane

Membrane proteins move laterally within the lipid bilayer, with less movement in areas referred to as ______, which have higher concentrations of cholesterol and saturated fatty acids.

Answer 5

lipid rafts

Question 6

Plasma Membrane

Integral membrane proteins include ______ for external ligands, ______ for passive or active movement of molecules across the membrane, and ______ for active membrane transport.

Answer 6

receptors, channels, pumps

Question 7

Plasma Membrane

______ is cellular uptake of macromolecules or fluid by plasma membrane engulfment or invagination, followed by the “pinching off ” of a filled membranous vesicle in the cytoplasm.

Answer 7

Endocytosis

Question 8

Plasma Membrane

Major types of endocytosis include ______ (uptake of particulate material), ______ (uptake of dissolved substances), and ______ (uptake of specific molecules bound to integral membrane receptor proteins)

Answer 8

phagocytosis, pinocytosis, receptor-mediated endocytosis

Question 9

Plasma Membrane

______ is a type of cellular secretion in which cytoplasmic membrane vesicles fuse with the plasma membrane and release their contents to the extracellular space.

Answer 9

Exocytosis

Question 10

Plasma Membrane

All types of ______ use membrane receptor proteins that are often linked to enzymes such as kinases or adenylyl cyclase whose activities initiate intracellular signaling pathways.

Answer 10

cell signaling

Question 11

The two ______, each a complex of rRNA and many proteins, attach to mRNA and translate that message into protein.

Answer 11

ribosomal subunits

Question 12

Multiple ribosomes on the same mRNA make up a ______ (______), and an abundance of these produces basophilic cytoplasm after H&E staining.

Answer 12

polyribosome, polysome

Question 13

The ______ is a convoluted network of membrane enclosing continuous spaces called ______ and extending from the nucleus to the plasma membrane.

Answer 13

ER, cisternae

Question 14

______ has a granular, basophilic cytoplasmic surface due to the presence of polysomes making most membrane proteins, proteins in certain other organelles, or for exocytosis; it is always well developed in cells actively secreting proteins.

Answer 14

Rough ER

Question 15

Proteins to be processed through the RER contain initial ______ which bind receptors in the ER membrane, localizing them to that organelle.

Answer 15

signal peptides

Question 16

After translocation across the membrane into the cisterna, the proteins undergo ______ in a process monitored by RER molecular chaperones and enzymes.

Answer 16

posttranslational modification and folding

Question 17

______ lacks ribosomes, but includes enzymes for lipid and glycogen metabolism, for detoxification reactions, and for temporary Ca2+ sequestration.

Answer 17

Smooth ER (SER)

Question 18

The ______ is a dynamic organelle consisting of stacked membranous cisternae in which proteins made in RER are ______ further and ______ for secretion or other roles.

Answer 18

Golgi apparatus, processed, packaged

Question 19

Proteins in ______ enter the cis or receiving face of the Golgi, move through medical cisternae of the Golgi network for enzymatic modifications, and are released in other vesicles at the trans face.

Answer 19

transport vesicles

Question 20

Vesicle movement through the Golgi apparatus is guided by specific ______ such as COPII and COPI.

Answer 20

coat proteins

Question 21

Important protein modifications in the Golgi apparatus include ______ and many ______ reactions.

Answer 21

sulfation, glycosylation

Question 22

Modified proteins leave the ______ after packaging in vesicles with coat proteins that direct movement to lysosomes, the plasma membrane, or secretion by exocytosis.

Answer 22

Golgi apparatus

Question 23

______ emerge from the Golgi apparatus containing inactive acid hydrolases specific for degrading a wide variety of cellular macromolecules.

______ are more heterogeneous, having fused with vesicles produced by endocytosis that contain material to be digested by the hydrolytic enzymes.

Answer 23

Primary lysosomes
Secondary lysosomes

Question 24

During ______, lysosomes digest unneeded or nonfunctional organelles after these are surrounded by membrane that then fuses with a lysosome.

Answer 24

autophagy

Question 25

Products of digestion in secondary lysosomes are released to the cytoplasm for reuse; final condensed vesicles containing any indigestible molecules are called ______.

Answer 25

residual bodies

Question 26

______ are small cytoplasmic protein complexes which degrade improperly folded proteins after they are tagged with the polypeptide ______.

Answer 26

Proteasomes, ubiquitin

Question 27

______ are the major sites of ATP synthesis and are abundant in cells or cytoplasmic regions where large amounts of energy are expended.

Answer 27

Mitochondria

Question 28

Mitochondria are usually ______ organelles and form by fission of preexisting mitochondria.

Answer 28

elongated

Question 29

Mitochondria have two membranes: a ______ outer membrane encloses the ______ and an inner membrane with many folds (______) enclosing a ______.

Answer 29

porous, intermembrane space, cristae, gel-like matrix

Question 30

Mitochondria The ______ contains enzymes for β-oxidation of fatty acids and the citric acid (Krebs) cycle.

Answer 30

mitochondrial matrix

Question 31

Mitochondria The inner membrane includes enzyme assemblies of the ______ and ______.

Answer 31

electron-transport system, ATP synthase

Question 32

Mitochondria of stressed cells may release ______ from the inner membrane, triggering a regulated series of events culminating in cell death (______).

Answer 32

cytochrome c, apoptosis

Question 33

______ are small spherical organelles containing enzymes for various metabolic reactions, notably for ______ and ______, and catalase that breaks down the H2O2 resulting from those reactions.

Answer 33

Peroxisomes, oxidation, detoxification

Question 34

The cytoskeleton contains three types of polymers: (1) ______ 25 nm in diameter; (2) ______ or ______ (5-7 nm); and (3) ______ (8-10 nm).

Answer 34

microtubules, actin filaments, microfilaments, intermediate filaments

Question 35

______ are semirigid tubular structures with walls composed of polymerized tubulin heterodimers; their structure is often very dynamic, with steady addition and dissociation of tubulin.

Answer 35

Microtubules

Question 36

Microtubules are important in maintaining ______ and as tracks for ______ of vesicles and organelles by the motor proteins kinesin and dynein.

Answer 36

cell shape, transport

Question 37

______ are short, flexible, highly dynamic filaments of actin subunits, in which changes in length and interactions with binding proteins regulate cytoplasmic viscosity and movement.

Answer 37

Microfilaments

Question 38

______ are motor proteins that bind and move along actin filaments, carrying vesicles or producing cytoplasmic movement.

Answer 38

Myosins

Question 39

Movements of cytoplasm produced by actin filaments and myosins are important for ______, cell ______ after mitosis, and ______ on substrates.

Answer 39

endocytosis, cleavage, cell locomotion

Question 40

______ are the most stable cytoskeletal component, conferring strong mechanical stability to cells.

Answer 40

Intermediate filaments

Question 41

Intermediate filaments are composed of various protein subunits in different cells; they include ______, nuclear ______, ______, and ______, which are especially important in epithelial cells.

Answer 41

vimentin, lamins, neurofilament proteins, keratins

Question 42

Unlike organelles, ______ are not metabolically active and are primarily storage sites, such as lipid droplets, glycogen granules, pigment granules, or residual bodies (also called ______).

Answer 42

inclusions, lipofuscin