3.4 The Cell Interior

Question 1

cytoskeleton

Answer 1

network of protein filaments and cylinders that structurally support a cell, determine its shape, organize its contents, direct the movement of materials within the cell, and contribute to movements of the cell as a whole

Question 2

microfilaments

Answer 2

6-nm-thick structures made of actin that are located throughout the cell and concentrated in the terminal web (membrane skeleton)

Question 3

intermediate filaments

Answer 3

thick and stiff structures that give the cell its shape, resist stress, and participate in junctions that attach cells to their neighbors

Question 4

microtubules

Answer 4

cylinders made of 13 parallel protofilaments

Question 5

protofilament

Answer 5

long chain of globular proteins called tubulin

Question 6

centrosome

Answer 6

the area of the cell from which microtubules radiate

Question 7

organelles

Answer 7

internal structures of a cell that carry out specialized metabolic tasks

Question 8

nucleus

Answer 8

the largest organelle, which contains the cell’s chromosomes and is the genetic control center of cellular activity

Question 9

nuclear envelope

Answer 9

a pair of membranes enclosing the nucleus of a cell, with prominent pores allowing traffic of molecules between the nucleoplasm and cytoplasm

Question 10

nuclear pore complex

Answer 10

ring of proteins that regulate molecular traffic through the nuclear envelope and hold its two membrane layers together

Question 11

nuclear lamina

Answer 11

narrow but densely fibrous zone inside the nuclear envelope composed of a web of intermediate filaments

Question 12

nucleoplasm

Answer 12

the material in the nucleus, including chromatin and nucleoli

Question 13

nucleoli

Answer 13

dark-staining masses where ribosomes are produced

Question 14

endoplasmic reticulum

Answer 14

an extensive system of interconnected cytoplasmic tubules or channels

Question 15

cisternae

Answer 15

fluid-filled spaces or sacs

Question 16

ribosomes

Answer 16

small granules of protein and RNA found in the nucleoli, in the cytosol, and on the outer surfaces of the rough eR and nuclear envelope

Question 17

Golgi complex

Answer 17

small system of cisternae that synthesize carbohydrates and put the finishing touches on protein and glycoprotein synthesis

Question 18

Golgi vesicle

Answer 18

membrane-bounded vesicle pinched from the Golgi complex, containing its chemical product

Question 19

secretory vesicle

Answer 19

vesicles that store a cell product, such as breast milk or digestive enzymes, for later release

Question 20

lysosome

Answer 20

a package of enzymes bounded by a membrane produced by the Golgi complex

Question 21

autophagy

Answer 21

digestion and disposal of surplus or nonvital organelles and other cell components in order to recycle their nutrients to more important cell needs

Question 22

autolysis

Answer 22

digestion of cells by their own internal enzymes

Question 23

peroxisomes

Answer 23

a package of enzymes produced by the endoplasmic reticulum

Question 24

catalase

Answer 24

an enzyme that breaks the excess from hydrogen peroxide into oxygen and water after oxidization

Question 25

proteasomes

Answer 25

hollow, cylindrical complexes of proteins located in both the cytoplasm and nucleus

Question 26

mitochondria

Answer 26

organelles specialized for synthesizing ATP

Question 27

cristae

Answer 27

folds in the inner membrane of mitochondria

Question 28

matrix

Answer 28

space between the cristae containing ribosomes

Question 29

centriole

Answer 29

short, cylindrical assembly of microtubules, arranged in nine groups of three microtubules each

Question 30

inclusions

Answer 30

any visible object in the cytoplasm other than an organelle or cytoplasmic element, e.g. accumulated cell products or foreign bodies