Cellular Motility

Question 1

Myosin 1

Answer 1

Has one head, tail binds to cell membrane, head binds to actin, and the direction of the head motion is toward the plus end of actin

Question 2

Myosin II

Answer 2

Two heads, tail binds to myosin II, head binds to actin, moves toward plus end

Question 3

Kinesin

Answer 3

Two heads, tail binds to vesicle and head binds to MT, direction of head moves towards plus end

Question 4

Dynein

Answer 4

Two heads, tail binds to vesicle, head binds to MT and moves toward minus head; moves vesicles from periphery of the cell toward the cell center

Question 5

How do kinesin and denein move?

Answer 5

hydrolysis of ATP

Question 6

Dynactin

Answer 6

dynein and the complex holding onto the vesicle- acts as a shock absorber

Question 7

Axonal transport

Answer 7

the synapse can release a neurotransmitter taken up by the plus end of the axon after which growth factors or whatever are taken back through the axon to the cell body via kinesin;
or the cell body can send vesicles of protein to the synapse via dynein

Question 8

gliding

Answer 8

myosin heads immobilized, actin filaments moving over;

MT can also be moved over the motor

Question 9

ameboid movement

Answer 9

based on actin, MT, and focal adhesions; move via actin polymerization- cell makes attachments to substrates via focal adhesions; the cell then has actin polymerize at the growing edge of the cell (lamellapodia) and at the back edge there is loss of focal adhesions and movement of unpolymerized actin

Question 10

lamellopodia

Answer 10

plus end of the cell moving in a wave like form;

Question 11

in a moving cell actin is concentrated where?

Answer 11

in the edge; right behind the concentrated actin is actin+cofilin which modifies the actin and disassembles it so that the cell can move forward

Question 12

focal adhesions

Answer 12

integrins consisting of two subunits: alpha and beta- both going through the plasma membrane and binding to extracellular matrix and the internal cytoskeleton

Question 13

alpha subunit of integrin

Answer 13

two chains linked by a disulfide linkae and a globular head with binding sites for divalent cations

Question 14

beta subunit of integrin

Answer 14

cytoskeleton side binds to vinculin, a-actinin, and talin which then bind to actin; extracellular side is rich in cysteine regions and binds to RGD domain (arginine, glycine, aspartic acid) on laminin and fibronectin

Question 15

focal adhesion complex activation

Answer 15

focal adhesion kinase can be activated to increase size of the focal adhesion complex;

Question 16

focal adhesion connection importance

Answer 16

connection to the matrix gives cell “traction” for movement and is a signalling complex that will alter intracellular environment

Question 17

How are MT brought to FA

Answer 17

by elongation or by motors; when MT touches FA, the GTP cap is destabilized and MT retracts by depolymerizing

Question 18

interaction between actin and MT-TCx will cause focal adhesion molecules to

Answer 18

disappear

Question 19

What happens once the MT binds to FA

Answer 19

this signals destabilization of the microtubules, and the microtubule also causes the disruption of the focal adhesion

Question 20

where are focal adhesions located

Answer 20

where actin filaments are attached to the cell membrane

Question 21

how do melanoma cells metastasize?

Answer 21

through the basement membrane by expressing many MMPs and demodeling the ECM to burrow through the basal lamina; they can then move throughout the body via the circulatory system and metastasize in liver and heart

Question 22

MMP

Answer 22

degradation of ECM during normal cell growth, turnover, etc.

Question 23

MMPs are involved in

Answer 23

embryonic development, tissue morphogenesis, wound repair, inflammatory diseases, cancer

Question 24

what type of collagen is degraded by MMP-2

Answer 24

Type IV collagen (a major component of basement membranes)

Question 25

activation of MMP-2

Answer 25

MT-MMP-1 must be activated which then cleaves Pro-MMP-2 which then becomes MMP-2

Question 26

MMP-2 inhibited by

Answer 26

TIMP- but it’s also activated by TIMP;

Question 27

ACtivation of MMP by TIMP

Answer 27

Active MT1-MMP binds to cell membrane via CD44H which then binds to TIMP2 and causes dimerization. The demerized protein can lead to MMP2 which can go and degrade ECM; The CD44H is then cleaved and the MT1-MMP is internized and degraded via the lysosome

Question 28

Cilia

Answer 28

MT based scaffold, dynein motor

Question 29

structure for cilia and flagella

Answer 29

axoneme- arranged in a 9+2 organization where 9 microtubules are arranged in a circle around 2 microtubules; the dynein foms a ring around the outer arms and the bottom of the microtubules are fixed and cannot slide; when the dynein is active i causes a shear (bending) force to create a circular motion in the cilia or flagella

Question 30

what movement causes cilia to move an object (mucus)

Answer 30

beating movement;

Question 31

beating frequency of cilia influenced by

Answer 31

mechanical simulation

Question 32

treadmilling

Answer 32

one end grows while other end shrinks