Cell Shape & Movement

Question 1

cytoskeleton functions

Answer 1

(1) maintain cell shape
(2) structural support
(3) locomotion / movement
(4) transport materials w/in cells

Question 2

types of cytoskeleton

Answer 2

(1) actin filaments
(2) intermediate filaments
(3) microtubules

Question 3

actin filament

Answer 3

• motor: myosin
• subunit: actin
• strucutre: strands in double helix
• 5-10% of total proteins in cell

aka microfilaments

Question 4

actin filament functions

Answer 4

(1) cell shape
(2) move cells
(3) divide animal cells in two
(4) move organelles & cytoplasm in plants, fungi & animals

Question 5

intermediate filament

Answer 5

• structure: fibers wound into thicker cables

- motor: none (purely strucutral fcn)

Question 6

intermediate filament subunits

Answer 6

(1) keratin
(2) lamins
(3) others

Question 7

intermediate filament function

Answer 7

(1) cell shape

(2) anchor nucleus & other organelles

Question 8

actin filament types of movement

Answer 8

(1) cytokinesis
(2) cytoplasmic streaming
(3) cell crawling
(4) muscle

Question 9

microtubule

Answer 9

• structure: hollow tube
• motor: dynein & kinesin
• subunits: ∝-tubuline & β-tubuline

Question 10

microtubule function

Answer 10

(1) cell shape
(2) move cells via flagella/cilia
(3) move chromosomes during cell division
(4) assist cell plate formation during plant cell division
(5) move organelles
(6) provide tracks for intracellular transport

Question 11

(+) end in microfilament

Answer 11

where things get on

Question 12

(-) end in microfilament

Answer 12

where things get off

Question 13

cytokinesis

Answer 13

division of cytoplasm to form 2 daughter cells

• process of cell division
• typically occurs immediately after nucleus divides in mitosis/meiosis
• actin-myosin interactions pinch membrane in 2

“cell-moving”

Question 14

cytoplasmic streaming

Answer 14

directed flow of cytosol & organelles (that facilitate material distribution) w/in plant & fungal cells

• occurs along actin filaments
• actin-myosin interactions move cytoplasm around cell
• common in large cells

Question 15

cell crawling

Answer 15

form of cellular movement

• involves actin filaments in which the cell produces bulges (pseudopodia) that stick to substrate & pull the cell forward
• occurs in wide range of organisms & cell types

(aka) amoeboid motion

Question 16

microtubule organizing center (MTOC)

Answer 16

any structure that organizes microtubules in cells

- where microtubules originate from

Question 17

centrosome

Answer 17

microtubules organizing center (MTOC) for cell’s cytoskeleton

• structure containing 2 centrioles
• responsible for spindle apparatus during cell division
• found only in animal & fungal cells

Question 18

centriole

Answer 18

1 of 2 small cylindrical structures found together w/in centrosome near nucleus of eukaryotic cell (not plants)

• microtubule triplets
• structurally identical w/ basal body

Question 19

basal body

Answer 19

microtubule organizing center for cilia & flagella in eukaryotic cells

• 9 triplets of microtubules arranged in circle
• establishes axoneme structures
• located @ base of microtubules
• important for axoneme growth
• foundation for microtubule

Question 20

cilium

Answer 20

one of many short, filamentous projections of some eukaryotic cells

• core = microtubules
• fcn: move cell & circulate fluid/particles around surface of stationary cell

Question 21

flagellum

Answer 21

long, cellular projection that undulates (eukaryotes) or rotates (prokaryotes) to move cell through aqueous environment

• longer than cilia
• abundance & pattern of movement diff. than cilia
• underlying organization identical to cilia

Question 22

axoneme

Answer 22

structure found in eukaryotic cilia/flagella

• responsible for their motion
• 2 central microtubules surrounded by 9+2 arrangement (nine doublet microtubules)