4 – Cell Organization and Motility

Question 1

Cheek cells

Answer 1

round

Question 2

Muscle cells

Answer 2

long tubes
-Multinuclear
-Long skinny tubes contract to short fat tubes

Question 3

Nerve cells

Answer 3

tree with branches

Question 4

Cytoskeleton – gives cell

Answer 4

shapes for what cells do

Question 5

Cells are internally organized & example

Answer 5

Intestine
Microvilli
Increase surface area for nutrient absorption/import

Question 6

Cells import & export cargo

Answer 6

Golgi apparatus –package insulin into secretory vesicles
Secretory vesicles – transports

Microtubules – roadway network of cargo by motor protein

Question 7

Cell internal skeleton:

Answer 7

Cytoskeleton: key roles in Cell physiology & metabolism

Question 8

Cytoskeleton - its key roles in cell physiology & metabolism (4)

Answer 8

-Shape, structure, stability – nerve cell
-Intracellular transport – Golgi/secretory vesicles…
-Spatial organization – microvilli (intestine)
-Contraction and motility –muscle cells

Question 9

Cytoskeleton – made of 3 major polymer systems

Answer 9

-Microfilaments
Actin filaments
-Microtubules
-Intermediate filaments

Question 10

Cytoskeleton = type of tensegrity structure (explain what it is)

Answer 10

maintained by tension between element within structure

Question 11

Microtubules are like…

Answer 11

poles
Very stiff – hard to bend
Resistant to compression

Question 12

Actin filaments are like…

Answer 12

wires
High tensile strength – can’t stretch/can’t handle compression
Flexible – take tension well

Question 13

Intermediate filaments are like…

Answer 13

ropes
Elastic & flexible

Question 14

Actin is an…

Answer 14

ATPase – drives cell motility

Question 15

what does actin do?

Answer 15

Actin polymerizes into a two-stranded helical filament
-Polymerizes: (+) (-) ends – arbitrary distinction

Question 16

Actin polymerizes In 3 distinct phases:

Answer 16

Nucleation – 3 G-actin collide and stick to form a nucleus for polymerization
-slow

Elongation – polymerizes by colliding at the end one by one = becomes F-actin (filamentous actin)

Steady state – no subunits available, only filaments

Question 17

actin polymerization Described by rate constants

Answer 17

ON rate constant - higher
-number of event by binding is higher because there is ahigher concentration

OFF rate constant - dissociation event driven by random kinetic event

Question 18

concentration at which ON event=OFF event

Answer 18

Critical concentration

Question 19

rate constant at the minus end is … then the plsu end

Answer 19

slower

Question 20

actin tread milling at steady state

Answer 20

result of imbalance of critical concentrations = actin does it at steady state
-plus end grows when minus end shrinks

Translocate in space
(+) end elongate – ATP state
(-) end shrink – ADP state

Question 21

Actin – major component of

Answer 21

muscle/microvilli/stress fibers

Question 22

Actin filaments – arranged

Answer 22

differently at distinct intracellular location

Question 23

leading edge contains…

Answer 23

branched network of actin filaments
-dendritic
-drive cell movement

Question 24

Cell motility

Answer 24

Long fibers = stress fibers – pull up the rear
Leading edge – pushes forward

Contains branched (“dendritic”) network of actin filament

Question 25

how do cells move?

Answer 25

Focal adhesion (foot)
Extension – cytoplasm body outward
Adhesion – new adhesion of lamellipodium
Translocation
De-adhesion & endocytic recycling

Question 26

Cells control:

Answer 26

Length
Number
Angle
Bundling
Orientation