cytoskeleton

Question 1

cytoskeleton is a network of

Answer 1

fibers
cell’s internal skeleton

Question 2

animal cells lack a

Answer 2

cell wall

Question 3

cytoskeleton function

Answer 3

• maintenance of cell shape; resists compression and torsion
• organization of structures within the cell
• organization of processes within the cell; division, movement
• cell motility; cilia, flagella, pseudopodia
• contraction of muscle cells

Question 4

cytoskeleton consists of 3 types of fibers;

Answer 4

• actin; microfilaments
• tubulin; microtubules
• intermediate filaments

Question 5

what is most abundant intracellular protein

Answer 5

actin

Question 6

actin is organized into

Answer 6

microfilaments
solid rods composed of globular actin proteins (subunits) organized into 2 intertwined strands

Question 7

actin is dispersed throughout the cytoplasm but forms a dense meshwork immediately beneath the

Answer 7

plasma membrane

Question 8

what determines and maintains the cell’s shape

Answer 8

actin

Question 9

actin provides mechanical strength by

Answer 9

resisting tensive forces

Question 10

actin in association w myosin filaments forms contractile structures such as

Answer 10

• muscle cells (sarcomeres)
• cleavage furrow of dividing cells
• pseudopodia

Question 11

bundles of ___ microfilaments make up the core of microvilli

Answer 11

actin

Question 12

tubulin is organized into

Answer 12

microtubules
hollow tubes composed of 13 columns of tubulin proteins with alpha and beta-tubulin protein subunits

Question 13

where is tubulin

Answer 13

distributed throughout cytoplasm

Question 14

tubulin functions to maintain cell shape via

Answer 14

compression resisting girders that radiate from centrosome

Question 15

tubulin acts as tracks which organelles can move such as

Answer 15

secretory vesicles from golgi to plasma membrane

Question 16

tubulin forms centrioles

Answer 16

• located within centrosome
• 9 sets of microtubule triplets
• involved in cell division (mitosis)

Question 17

during mitosis; centrioles

Answer 17

• move to opposite ends of the cell, microtubules extend from one centriole to the other: spindle
• daughter chromosomes pulled towards each centriole

Question 18

_____ also present in cilia and flagella

Answer 18

microtubules

Question 19

what is the only flagellated animal cell

Answer 19

sperm

Question 20

both cilia and flagella have a _____ microtubule arrangement and at the base is a

Answer 20

9+2
basal body = centriole

Question 21

intermediate filaments are

Answer 21

fibrous proteins that are coiled to form thick cables

Question 22

intermediate filaments consist of structurally related proteins including

Answer 22

keraitns, vimentin, demsin, neurofilaments

Question 23

where are intermediate filaments

Answer 23

distributed throughout cell

Question 24

intermediate filaments provide maintenance of cell shape by being

Answer 24

tension bearing, anchored to cell membrane

Question 25

nucleus is enclosed within a cage of

Answer 25

intermediate filaments

Question 26

5 major classes of intermediate filaments

Answer 26

1) keratin: skin epithelial cells, forms desmosomes
2) vimentin; epithelial cells, neural cells
3) desmin; muscle cells
4) glial filaments; glial cells
5) neurofilaments; neurons

Question 27

Which of the following statements about the cytoskeleton is INCORRECT?

A.
Actin is dispersed throughout the cytoplasm but forms a dense meshwork beneath the plasma membrane, where it provides mechanical strength by resisting tensive forces

B.
Intermediate filaments anchor the nucleus in its characteristic position for each cell type and also provide mechanical strength to microvilli

C.
Actin is a major component of sarcomeres, the contractile ring associated with the cleavage furrow of dividing cells, and the pseudopodia of amoebae, macrophages, and neutrophils

D.
Tubulin microtubules radiate from the centrosome, forming the tracks along which secretory vesicles travel when moving from the Golgi apparatus to the plasma membrane; tubulin is also organised into centrioles

Answer 27

Intermediate filaments anchor the nucleus in its characteristic position for each cell type and also provide mechanical strength to microvilli

Question 28

Which of the following statements about the cytoskeleton is INCORRECT?

A.
Actin is concentrated beneath the plasma membrane, where it provides mechanical strength by resisting tensive forces; it also supports the structure of microvilli

B.
Intermediate filaments are responsible for the maintenance of cell shape and anchoring of the nucleus, and are a component of desmosomes

C.
Actin forms the contractile ring associated with the cleavage furrow of dividing cells, and the pseudopodia of amoebae, macrophages, and neutrophils

D.
Tubulin microtubules form centrioles, cilia, and flagella, which consist of nine sets of microtubule doublets plus a central pair (i.e., 9 + 2 arrangement)

Answer 28

D.
Tubulin microtubules form centrioles, cilia, and flagella, which consist of nine sets of microtubule doublets plus a central pair (i.e., 9 + 2 arrangement)