Bsci 330 Exam 3: 4/7

Front 1

do microtubules grow and shrink in length during the lifetime?

Back 1

yes....most of them

Front 2

microtubules that form the spindle fibers during chromosome divsion are _________?

Back 2

changing

Front 3

microtubules in cilia are highly ______ in length

Back 3

stable

Front 4

where is there a lot of alpha-beta tubulin dimers ?

what does it do?

Back 4

in the cytoplasm

forms new microtubules at MTOC's by nucleation

also, the pool of dimers also changes which dimer is on the positive end of the microtubule

Front 5

what is the growth or shrinkage of microtbule dependent on?

Back 5

whether the rate of addition of new dimers is greater or less than the loss of old ones

Front 6

dynamic instability

Back 6

when no addition occurs to microtubules

they will shrink in length

Front 7

how long does it take for microtubules to shrink in length when no dimers are being added?

Back 7

a couple of minutes

Front 8

describe the position of microtubules in a plant cell during mitosis

Back 8

interphase: edge

approaching mitosis: no microtubules on cortex except
pre-prophase band

mitosis: spindle

after mitosis: replaced by phragmoplast which separates daughter nuclei

Front 9

cilia

found in?

movement?

structure?

Back 9

hairlike motile structures

extensions of the plasma membrane with complex, microtubule-based cytoskeleton

oar like movement

epithelial cell lining : lungs and oviducts

surface of ciliated protozoa

Front 10

oviduct

Back 10

move particles, eggs along

Front 11

epithelium

Back 11

layers of cells that line the cavities and surfaces of cells throughout our body

Front 12

flagella

structure

in what?

what does it do?

Back 12

hairlike motile structure

extensions of the plasma membrane with microtubule based cytoskeleton

waves of motion run along the length of the flagellum: provide motile force to algea and protozoa

Front 13

how is the locomotion of an object determined by the movement of flaggella

Back 13

it will always go the opposite direction of the power stroke

Front 14

what happens after the power stroke in flagella and cilia?

Back 14

there is a recovery stroke

Front 15

where are the positive ends of microtubules in cilium?

Back 15

at the tip of the cilium

Front 16

motion of cilium requires what?

Back 16

atp

Front 17

dynein arms have what?

Back 17

atp-ase activity

Front 18

draw the structure of a cilia and flagella

Back 18

corey joseph likes men

Front 19

describe dyneins purpose in cilia and flagella structure

Back 19

connect periphial microtubules

Front 20

what family is the dynein in cillia?

Back 20

axonemal dynein

Front 21

where do cillia and flagella originate from?

Back 21

basal body

Front 22

why do cilia and flagella move?

Back 22

1)dynein arm on alpha tubule attach to binding sites on beta tubule

2) a conformational change occurs in dynein which causes a power stroke

3) due to radial spokes this stroke can only go so far...(dyneins will release)

4) once

Front 23

size of intermediate filaments

Back 23

intermediate in size between microtubules and actin microfilaminets

Front 24

where have intermediate filaments been identified?

Back 24

in animals only so far

Front 25

plectins

Back 25

wispy cross-bridging proteins

Front 26

what are the filaments in cells linked by

Back 26

plectins

sometimes microtubules

Front 27

what are filaments resistant to?

Back 27

pulling

Front 28

what is the general structure of intermediate filaments

Back 28

aa

Front 29

do intermediate filaments have polarity?

Back 29

no

Front 30

where is keratinfound?

Back 30

epidermal and epithelial cells

Front 31

epidermal cells

Back 31

outermost layer of skin

Front 32

desmosins

Back 32

join cells together

Front 33

what kind of network do keratins form

Back 33

elaborate cage like network

Front 34

what is the outer layer of skin made from?

Back 34

a waterproof airtight mat of keratin filaments

Front 35

what happens to mice if they lack keratin

Back 35

sensitve to mechanical pressure...skin blistering...human genetic condition ebs

Front 36

name 3 types of intermediate filaments

Back 36

keratin
neurofilaments
desmin

Front 37

desmin

Back 37

maintains aligment of myofibrils in smooth muscle cells

Front 38

neurofilaments

Back 38

run along nerve cell axons

Front 39

what do neurofilament tangles cause

Back 39

ALS....lou gehrigs disease

Front 40

als

Back 40

caused by neurofilament tangles

these impede normal vesicle transport down axons and lead to death of neurons

Front 41

what is the basis of the contractile cytoskeleton in muscle cells and non-muscle cells?

Back 41

actin microfilaments

Front 42

what is the structure of actin

Back 42

composed of globular actin monomers G-actin

2 strands of monomeres are wound together into a stiff filament

Front 43

what supports the non-motile cellular structure like microvilli in forming the membrane skeleton beneath the plasma membrane?

Back 43

actin microfilaments (F-actin)

Front 44

is actin a major or minor protein in cells and how is it conserved

Back 44

major

highly conserved

Front 45

how is F-actin polarized

Back 45

has a + and - end

Front 46

how can polarization of actin be visualized?

Back 46

by adding myosin S1 head fragments which bind to and decorate the actin filaments

arrowhead appearence is created and the pointed end will be the minus end

Front 47

F-actin assembly

Back 47

A pool of G-actin monomers exists in the cytoplasm.

G-actin binds ATP

G-actin w/ATP bound can add onto both ends of filament, but much faster addition occurs at the (+) end.

Since G-actin can also dissociate from the filament at both ends, net growth tends to occur at the (+) end and net loss is more likely, sometimes, at the (-) end.

A dynamic equilibrium at both ends therefore determines filament length

After addition, ATP is hydrolysed to ADP after some time. G-actins with ADP bound are more prone to dissociate from the filament.

In fast-growing microfilaments a stabilizing “ATP-cap” is therefore created at the (+) end.