Lecture 5- Cytomotility

Question 1

What triggers cytomotility?

Answer 1

transmembrane receptors (cell surface receptors) from the external environment
eg. hormones, growth factors, bacterial peptides.

Question 2

What happens when cytomotility occurs?

Answer 2

calcium is released.
actin polymerization occurs bc it is dependent on calcium.
shape change occurs with movement

Question 3

What are the two types of migration responses?

Answer 3

chemotaxis and heptotaxis.

Question 4

What is chemotaxis?

Answer 4

(White blood) cells move up the concentration gradient towards the higher concentration of bacteria in SOLUTION.
-has to do with wound fluid
-macrophages migrating toward bacterial proteins
(better explanation in notes)

Question 5

What is haptotaxis?

Answer 5

after chemotaxis, bound factors (INSOLUBLE peptides) are left behind and the skin cells move up a HIGHER concentration gradient to be able heal the wound.

Question 6

What is the difference between chemotaxis and haptotaxis

Answer 6

THE DIFF IS THE STIMULUS
chemotaxis: attractive factor IN SOLUTION (soluble)
haptotaxis: INSOLUBLE factors bound to a surface (peptides)

Question 7

What are the roles of the cytoskeleton?

Answer 7

amoeboid motility.
metastasis
infection clearing
wound healing

Question 8

What is amoeboid motility?

Answer 8

cell movement in response to chemotaxis or hepatotaxis
-mostly actin based mechanism
-sometimes membrane extension from microtubule.
allows for wound healing and metastasis

Question 9

What type of cells occur in wound healing?

Answer 9

WBC and Skin cells. epithelial and fibroblast migration.

Question 10

What type of cells occur in metastasis?

Answer 10

cancer cells migrate beyond tumor through connective tissue, through vessel then back through connective tissue.

Question 11

What occurs in both phagocytosis and wound healing?

Answer 11

WBC

Question 12

What occurs in infection clearing?

Answer 12

WBC migration to infection.

Question 13

What is treadmilling?

Answer 13

microfilament movement (actin)
polymerization/ depolymerization
results- extends stress fibers and membrane pushed forward

Question 14

Where does treadmilling occur?

Answer 14

in any migratory cell
whether it is chemotaxis or heptotaxis, you will get treadmilling or ameboid movement.

Question 15

What is PAR?

Answer 15

protrusion, attachment, retraction

Question 16

What does the P in PAR stand for?

Answer 16

protrusion- extension
-results in treadmilling
-gets you filopodia (narrow shape) and lamellipodia (flat shape)

Question 17

What does the A in PAR stand for?

Answer 17

Attachment- connection
filopodia and lamellipodia make contact on (adhesion plaque=focal contact)
-accessory proteins (vinculin and talin) then have a complex interaction with integrin dimers on extracellular surface which makes them interact with the external enviroment.
-stress fibers are made out of microfilaments here.

Question 18

What does the R in PAR stand for

Answer 18

Retraction- Release.
causes detachment from substrate.
adhesion plaque disassembly & dependent on microfilament depolymerization

Question 19

What is an adhesion plaque?

Answer 19

transmembrane interaction between extracellular matrix and actin cytoskeleton

Question 20

What is focal contact?

Answer 20

underlying substrate

Question 21

Where does adhesion plaque disassembly have to be in order for retraction to occur?

Answer 21

in the trailing end of the microfilament.

Question 22

What are the two transient structures in intracellular movement of microfilaments?

Answer 22

contractile rings and vesicle movement (myosin-1)

Question 23

What are contractile rings?

Answer 23

wrap around the midpoint of the cell to accomplish cytokinesis.

Question 24

What is vesicle movement?

Answer 24

actin filament is always attached to a myosin I motor protein.

Question 25

What happens when the vesicle reaches the cell membrane

Answer 25

myosin-I walks along the microfilament, the vesicle moves too, and releases its contents causing secretion and excretion.

Question 26

How is filopodia and phagocytosis used in intracellular movement of a microfilament?

Answer 26

filopodia is used for movement and phagocytosis is used for extension. occurs upon stimulus but sometimes stimulus not available.

Question 27

What is a stable structure?

Answer 27

a sarcomere for muscle contraction

Question 28

In the stable structure of a sarcomere, what is included?

Answer 28

long term association of actin and MYOSIN 2 (II) PROTEIN. allows for stability, gives muscle repeated ability to contract.

Question 29

What two motor proteins are needed for organelle movement in a microtubule?

Answer 29

kinesins (+ extracellular) and dyenins (- intracellular)

Question 30

What is the Microtubule network considered to be?

Answer 30

bidirectional

Question 31

What are motor proteins considered to be?

Answer 31

unidirection, they only move ONE WAY.

Question 32

How is organelle movement done with a microtubule?

Answer 32

motor proteins form a bridge between the organelle and the microtubule.

Question 33

What are the 3 types of transient in a microtubule?

Answer 33

membrane extension, chromosome separation, and organelle movement.

Question 34

What is membrane extension in a microtubule?

Answer 34

need polymerization on the + end of microtubule.

Question 35

How can you get chromosome separation of microtubule?

Answer 35

coordination of polymerization at the midline and depolymerization at the pole of the mitotic spindle.

Question 36

How can you get organelle movement in a microtubule?

Answer 36

require motor proteins kinesins (+) and dyneins (-)

Question 37

What affect does taxol have on the mitotic spindle?

Answer 37

it would stabilize the polymer more polymerization built up the less seperation. LESS CHROMOSOME SEPARATION.

Question 38

what is stable in a microtubule?

Answer 38

flagella and cilia. stable membrane extensions with stable microtubule assemblies.

Question 39

What is needed for motor proteins to make a bridge between the organelle and the microtubule?

Answer 39

ATP!

Question 40

what happened to the mouse when it was just missing 1 of the 14 kinesins bc of mutation

Answer 40

it had defective transport and synapse dysfunction.

Question 41

Kinesins are towards what?

Answer 41

(+)the tip of the microtubule, involves: receptors and transmitters

Question 42

dyneins are towards what?

Answer 42

(-) towards cell body. involves: cell membrane vesicles (retrograde transport- transport of vesicles)

Question 43

What is the importance of motor associated proteins?

Answer 43

hyperphosphorylated tau in alzheimers decrease microtubule instability decrease axonal transport- neuron function.

Question 44

What do cilia and flagella both have to do with?

Answer 44

the ring of the microtubule and motor protein dyenin.

Question 45

What is the function of cilia in a microtubule?

Answer 45

MOVES THE fluid over cell surface. respiratory epithelial cell

Question 46

What is the function of flagella in a microtubule?

Answer 46

movement propels THROUGH fluid. sperm cell.

Question 47

where did they find taste receptors in the experiment using microtubules?

Answer 47

on cilia membrane

Question 48

What was the chemical response experiment with cilia and the taste receptors (transmembrane proteins).

Answer 48

cells that were exposed to bitter compounds. INCREASED intracellular calcium levels which INCREASE CILIA BEATING helpful in cystic fibrosis :)