Cytoskeleton & Cell Division

Question 1

What are the functions of cytoskeleton?

Answer 1

1. Provide STRUCTURAL SUPPORT for plasma membrane & cell organelles
2. Intracellular MOVEMENT/transport of substances (large molecules/organelles)
3. Cell LOCOMOTION (amoeboid movement, embryonic development, cilia, flagella)
4. Mm CONTRACTION (specialized cells)

Question 2

What are the 3 main elements of cytoskeleton?

Answer 2

1. microfilaments
2. intermediate filaments
3. microtubules

Question 3

Element of cytoskeleton that is distributed in 3D network throughout cytoplasm

Answer 3

microfilaments

Question 4

Why are microfilaments important?

Answer 4

maintain CELL SHAPE

facilitate shape CHANGES during MOVEMENT

Question 5

Examples of microfilaments acting in body:

Answer 5

wound contraction during healing

muscle contraction

Question 6

Microfilament that is known as the “thin” filament (6-8 nm diameter):

Answer 6

actin

Question 7

Actin strands are made of smaller _____ subunits

Answer 7

G-actin (monomers)

Question 8

small, globular protein monomer

Answer 8

G-actin

Question 9

polymerizes to form protofilaments

Answer 9

G-actin

Question 10

2 protofilaments twist together to form:

Answer 10

double-helix (F-actin)

Question 11

Where is actin located and what does it link to?

Answer 11

beneath PM

filamin (protein)

Question 12

Actin forms a support meshwork called ___ ___

Answer 12

cell cortex (terminal web)

Question 13

Actin prevents the cell from what?

Answer 13

deformation

Question 14

Where can actin be found other than beneath the PM?

Answer 14

microvilli

stereocilia

Question 15

known as the “thick” filament (~15 nm diameter)

Answer 15

myosin (2x size actin)

Question 16

What is myosin classified as?

Answer 16

motor protein

*along with DYNEIN & KINESIN

Question 17

What is the shape of myosin molecules?

Answer 17

long and rod-shaped
GLOBULAR heads
form thick, ropy “cables” with myosin heads sticking out side

Question 18

Myosin heads form _____ between adjacent filaments

Answer 18

cross-bridges

Question 19

What is required for movement of myosin filaments for mm contraction?

Answer 19

Ca

ATP

Question 20

Element of cytoskeleton that is 8-10 10-15 nm in diameter (middle of microfilaments and microtubules) and has 1’ structural function

Answer 20

intermediate filaments

Question 21

Element of cytoskeleton that forms large filaments that bind with intracellular structures

Answer 21

intermediate filaments

Question 22

Why are intermediate filaments useful?

Answer 22

immunohistology and tumor ID

Question 23

Part of intermediate filament that is characteristic of all epithelial cells and forms tonofibrils is skin epidermis

Answer 23

(cyto)keratin

Question 24

Part of intermediate filament that is found in MESODERMAL cells of MESENCHYMAL origin (includes endothelial cells, muscle & neuroectodermal cells)

Answer 24

vimentin

Question 25

Part of intermediate filament that is unique to MUSCLE cells; mesodermal origin

Answer 25

DESMIN

Question 26

Part of intermediate filament that is present in NERVE cells (neurons)

Answer 26

neurofilament proteins

Question 27

Part of intermediate filament that is found in glial (support) cells of nervous system (astrocytes)

Answer 27

GFAP (glial fibrillary acidic protein)

Question 28

Part of intermediate filament that forms layer on inside of nuclear membrane (support)

Answer 28

lamin

Question 29

Element of cytoskeleton that is larger than microfilaments or intermediate filaments (24 nm)

Answer 29

microtubules

Question 30

Element of cytoskeleton that is composed of 2 types of globular protein subunits

Answer 30

microtubules

Question 31

What are the 2 types of globular protein subunits in MT and how are they arranged?

Answer 31

alpha and beta tubulin | coiled, spiral pattern

Question 32

Element of cytoskeleton that polymerizes to form hollow tubes—readily assemble & disassemble

Answer 32

MT

Question 33

Functions of MTs:

Answer 33

cell movement maintain cell shape intracellular transport of substances

Question 34

How does movement occur in MTs?

Answer 34

addition and subtraction of tubulin subunits from MTs

Question 35

Which motor proteins attach MTs to organelles and what is the function?

Answer 35

dynein and kynesin | movement in cytoplasm

Question 36

What is the function fo various MAP's (microtubule-associated proteins)?

Answer 36

provide energy as ATPase

Question 37

What helps stabilize MTs?

Answer 37

capping proteins | MAPs

Question 38

Example of MT

Answer 38

cell spindle during cell division

Question 39

Which drugs inhibit polymerization of MTs and cell division?

Answer 39

colchicine | vincristine & vinblastin (chemo)

Question 40

What effect do drugs like colchicine or vincristine & vinblastin (chemo) have on MTs?

Answer 40

inhibit polymerization and cell division

Question 41

Where are MTs found in?

Answer 41

cilia & flagella centrioles basal bodies of cilia mitotic spindles

Question 42

9 pairs of microtubules (peripheral doublets) containing dynein arms arranged in circle with central doublet in middle (9+2 structure)

Answer 42

axoneme

Question 43

arrangement of cilia and flagella

Answer 43

axoneme

Question 44

Central doublet connects to peripheral doublets by _____ & peripheral doublets connect to each other by protein ____

Answer 44

radial spokes | nexin

Question 45

In cilia, axoneme grows from _______, derived from modified ______

Answer 45

basal body | centriole

Question 46

Where are centrioles located?

Answer 46

centrosomes ("cell center") near nucleus

Question 47

function of centrioles

Answer 47

cell divison

Question 48

During cell division, pair of ______ (= diplosome) orient at right angles to each other within centrosome

Answer 48

centrioles

Question 49

Each centriole consists of 9 ____ of microtubules arranged in a ______

Answer 49

triplets | cylinder

Question 50

Centrioles act as a _____ _____ for MTs.

Answer 50

nucleation center

Question 51

During _____, centrioles divide—each pair goes to opposite poles of cell

Answer 51

mitosis

Question 52

Centrioles form _____ _____, which controls distribution of chromosomes in daughter cells

Answer 52

mitotic spindle

Question 53

Function of mitotic spindle

Answer 53

controls distribution of chromosomes in daughter cells

Question 54

How does movement of chromosomes occur during cell division?

Answer 54

addition & subtraction of tubulin subunits & attachment proteins (e.g., dynein & kynesin) to chromatids at kinetochore (= centromere)