Subcellular Architecture of the Eukaryotic Cell

Question 1

Actin

Answer 1

A globular protein that links into chains. When two chains of actins are helically twisted, they form microfilaments in muscle and other kinds of cells.

Question 2

Chloroplast

Answer 2

A double-membrane bound organelle that is the site of photosynthesis.

Question 3

Cytoskeleton

Answer 3

A complex scaffold of proteins within the cytoplasm made up of three major components: microfilaments, intermediate filaments, and microtubules.

Question 4

Endomembrane system

Answer 4

A network of membrane-bound chambers where protein production and modification take place.

Question 5

Golgi apparatus

Answer 5

A component of the endomembrane system involved in processing proteins.

Question 6

Hydrolytic enzyme (hydrolase)

Answer 6

A general category of enzymes that have the ability to hydrolyze (decompose by reacting with water) various substrates. Lysosomes house some hydrolytic enzymes that degrade material within the vesicles.

Question 7

Intermediate filament

Answer 7

A thick, cable-like structure made of fibrous proteins wrapped around one another. Intermediate filaments support cell structures and anchor organelles in the correct position within the cell.

Question 8

Lysosome

Answer 8

An eukaryotic membrane-bound compartment involved in breaking down materials.

Question 9

Microfilament

Answer 9

The smallest cytoskeletal fibers made of polymerized subunits of actin. Microfilaments facilitate cellular migration or contraction of muscle cells.

Question 10

Mitochondrion

Answer 10

A double-membrane bound orgallele that is the location of cellular respiration.

Question 11

Myosin fiber

Answer 11

A type of motor protein that associates into filaments that interact with actin filaments to cause cell contraction.

Question 12

Nuclear pore

Answer 12

Pores in the nuclear envelope that allows messenger RNAs to exit the nucleus

Question 13

Nucleus

Answer 13

One of the most visible organelles in the cell. It contains the genetic material and is surrounded by a double membrane called the nuclear envelope.

Question 14

Organelle

Answer 14

Organelles are specialized structures that are separated from the rest of the cell by a phospholipid bilayer. Some prokaryotes contain rudimentary organelles.

Question 15

Ribosome

Answer 15

Structures made of ribosomal RNA molecules and proteins and are the sites of protein synthesis in cells.

Question 16

Rough endoplasmic reticulum

Answer 16

A type of endoplasmic reticulum (ER) that houses ribosomes on its surface, which is where many of the proteins targeted for export outside the cell are synthesized. Ribosomes on its surface gives this organelle a “rough” appearance.

Question 17

Secretory vesicle

Answer 17

The final transport vesicle that buds from the trans face of the Golgi apparatus. Secretory vesicles bind and fuse with the internal face of the plasma membrane by interacting with specific membrane proteins.

Question 18

Signal sequence

Answer 18

A sequence of amino acids that directs newly synthesized proteins destined for export to the rough endoplasmic reticulum.

Question 19

Signal recognition particle (SRP)

Answer 19

A protein RNA complex that binds to the growing polypeptide and facilitates association with the rough ER and guides it to a specific receptor site located within rough ER pore complexes.

Question 20

Smooth endoplasmic reticulum

Answer 20

A type of endoplasmic reticulum (ER) that synthesizes lipids and degrades toxins. The surface of smooth ER lacks ribosomes, and therefore appearing smooth.