Epithelium: Cytoskeleton Flashcards Preview

HIstology > Epithelium: Cytoskeleton > Flashcards

Flashcards in Epithelium: Cytoskeleton Deck (76):
1

In the intestinal microvilli...Identify 

What type of epithelia is present

left to right

Line 1

Line 2

Q image thumb

Ciliated Columnar

 

Brush border

Goblet Cell

2

Intestine

Identify (left to right)

Line 1

Line 2

LIne 3

LIne 4

Bottom third

Left to right

Line 1 

Line 2

Q image thumb

Cap 

Intestinal microvillus

Actin Bundle

Glycocalyx

 

Actinf ilament rootlets

Terminal Web

3

Microvilli and sterocillia have what type of core?

F-Actin

4

where are microvili found?

In the small intestine-brushborder (columnar)

and the kidney-nephron (cuboidal)

5

Microvilli serve what purpose?

to increase the absorbative surface

6

What protien is seen inside the cap of microvilli?

Formin(caps the barbed end) 

promotes the enlongation of unbranched f-actin

7

How wide is f-actin?

7um

8

What are the actin cross linking protiens found in microvilli?

Villin

fimbrin

both stablize the actin bundle

9

What are the membrane linking protiens found in microvilil?

myson I and Calmodulin

10

What purpose does Glycocalyx serve and where is it found?

It is a plasma memebrane coat of enzymes which breakdown protien and carbohydrates during absorbtion (small intestine)

11

The terminal web is seen at the base of ...

and what does it consist of?

Microvilli

it consist of IF and spectrin

12

What are the affects of cytochalsins on F-actin?

 

Where is it found

bind to fast growing end (+) (caps it)

prevent addition of G-actin

 

Found in Fungi (alkoloids)

 

13

What are the effects of Phalloidin on F-actin?

It binds to actin filaments preventing their depolarization

 

foudn in mushrooms (alkoloid)

14

What are the effects of Latroneulins on F-actin?

Binds to G actin and induces F -actin depolarization

15

In microfilements Polymerzation is dependant on what?

ATP

Occurs at (+) barbed end

16

Profilin is a...

ADP-ATP Exchanger seen at the barbed end

promotes the transfer of actin monomers from thymosin to the barbed end of the actin filament

 

regulates filament assembly 

17

Gelsolin...

Severing/capping protien

binds to the newly formed plus end

Blocks further polymerization

18

Cofilin

Actin depolymzerzation factor

stimulates the dissasocation of ADP bound B actin 

19

What is treadmilling?

 

Steps of Treadmilling

The balence between polymerization and depolymerization of F-actin

Pointed ends grow less rapidly then the barbed ends

Steps

1. Thymosin (sequesters G actin into reserve pool)

2. Profilin binds to G-actin (goes from ADP to ATP)

3. GTP-Actin binds to the barbed end (+)

4. Once attached ATP hydrolyized to ADP-actin

5. Cofillin (stimulates the disassocation of GDP-Actin from  pointed end (-).

 

20

WASP is seen where?

What does it do?

In F-actin

it is a branching protien (activates ATP for branching)

Works with Arp 2/3(actin related protien) to branch

21

WAS is due to a defect in 

WASP 

low latelet count

immunodeficiency

respiratory infections 

22

F-Actin

Made out of..

Depend on what for assembly?

Moter protiens

State

G-actin

ATP-dependant

Double helical and BRanching

 

Treadmilling

Myosin Va/vIia (muscle contraction)

23

Actin filaments (microfilaments) are involved in ..

cell motility...and cargo stransport

24

Microtubles are involved in...

cell motility and cargo transport

25

intermediate filaments provide

mechanical strength

skin support

stability

26

Direct immunoflorescence

 

Adv

Disadv

adv: direct attachment of de to primary antibody

faster

 

disadv

less senstiive then indirect

27

Indirect immunofluorescence

Adv: uses two antibodies (more specfic)

Disadv: complex..time consuming

28

Limitations of Immunofluorescence Microscropy

1. photobleaching

2.limited to fixed cells/tissues (dead)

If uses Green fluorescent protien (jelly fish) can use of live 

29

Identify type of cytoskelteon from left to right

Q image thumb

Intermediat fil (10)

Microtubles (25)

Actinfilament bundle (7)

30

Q image thumb

A image thumb
31

Where are intermediate filaments found?

throughout the cytoplasm

surround the nucleus

extending out to the cell peripherty

 

anchored to cell junctions (SPOT desmosomes)-connect to adjacent epithelial cells

 

Anchored to hemidesmosomes-connect epithelial cell to ECM

nuclear lamina

32

How are intermediate filaments formed?

 

 

 

1Monomer

2. dimer (parallel arangment)

3. tetramer (antiparallel arrangment +side by side)

4. protofilament (tetramers align end to end)

5. protofibril (protofilaments align side by side)

6. intermeidate filaments (8 protofibrils wind up_

 

33

What does phosphorylation do to Intermediate filaments?

diassemble 

34

What does dephosphorylation do to IF?

promote assembly

35

Classification of IF

I/II

III

IV

V

IV

I/II- epithelial cells..keratins

 

III- mesenchymal derived cells

vimentin (fibroblast, smooth muscle, WBC)

Desmin ( muscle cells)

 

IV- Neurofilaments

 

V-Nuclear Lamins (A,B,C)

found in eukaryotic cells/ part of nucleus

 

VI- nestin (neurons) 

embroynic development of stem cells 

 

36

Epidermolysis Bullosa Simples (EBS)...

defect in keratin

cant form strong IF

weak 

blisters after minor trauma

37

Excessive Keratinzation

skin becomes cracked for fragmented 

38

Keratin provides...to epithelial cells

mechanical strength 

39

Nuclear Lamina is associated to...

inner nuclear membrane

40

What are the only organelles surround by a double membrane?

Mitocondria and Nucleus

41

Nuclear Lamina contains

Lamins (type V IF)

 

42

Lamins..

are connected to the inner and outer membranes of the nuclear envelope by several protiens  

43

Lamins are divided into Type A and Type B lamins 

describe

Type A: lamin A and C (derived from single gene LMNA)

 

Type B: Lamin B encoded by two genes LMNB1 AND LMNB2

 

LAMINS ARE EXPOSED TO CHROMATIN IN THE INNER MEMBRANE 

44

Structural alterations of Lamins ...

impact integrity of the nucleus

nuclear fragility

decrease of gene expression

eventual nuclear destruction

 

45

Laminopathies

Progeria (premature aging) LMNA gene

repture of the nuclear envelope and release of chromatin

 

Emery-Drifuss Muscular Dystrophy Emerin deficiency

Greenberg skeletal dysplasia LBR defc

46

Microtubules are composed of

tublin dimers which polymerize in the presence of GTP 

47

Microtubules main function

cell division ...and cargo transport

 

48

Describe the structure of microtubules

long and hollow tubues of protiens

beta tublin is exposed at the the (+) end faster gorwing end 

alpha tublin is exposed at the (-) end sower growing end

 

dynamically unstable: rapidly assemble in one site and disassemble in another site 

results from 

hydrolysis of GTP-tublin dimers , releeased of hydrolyzed phosophate and subsequen release of GDP-tublin subunits

49

Microtubules grow out from

Centrosomes

50

Microtubule motor protiens

Kinesin (anterograde)

dynein (retrograde)

51

Microtubules can form transient and permenant structures..

transient: miotic spindle

cytoplasmic MTs diassemble and then reassemble to form the mitotic sspindle( separates chromsomes equally into two daughter cells)

 

Permenant

Axoneme of cilia (9+2) 

Flagella sperm

52

Microtubule associated protiens (MAPs)

facilitate assembly and prevent diassembly

 

53

Centrosome

Function as microtubule orangizing center 

minus ends of hte microtubules are anchored 

54

Types of microtubless (3)

kinetochore

Polar 

Astrial (radiating) 

55

Mitotic Center (centrosome)

Microtuble organizing center

centrioles (2)

Radiating microtubules/ astrial (extend outward to cell periphery)

56

Mitotic apparatus 

centrosome (mitotic center)

+

spindle

57

Mitotic spndle

kinetechore microtubules (assembles on centromere)

+

Polar microtubules (overlap with one another in the center of the cell..not attached to chromosomes) 

 

repsonsible for separation of daughter chromosomes 

58

Centrosome

MT organizing center

Main protien (gamma tubulin)

Minus ends of MT anchored to centrosome

plus end grows away

 

Consist of

2 Centrioles (perpendicular orientation to one another) 

(9+0)

surrounded by amorphous pericentriolar material

centriole generates basal bodies(forms cilia and flagella)

 

 

 

 

59

Vocabulary

 

Kinetochore

complex of protiens assembled on centromeric DNA during mitosis and meisosic

 

(dot on centromere)

 

the asembly of the kinetechore depends ont he presence of centromeric DNA Sequences

60

Vocabulary

 

Centromere

chromosomal site where the kinetochore assembles

narrow chromatin region on metaphase chromosomes 

primary constiriction

61

Antimitotic Drugs

 

Colchicine

TOXIC NOT USED IN TREATMENT OF TUMORS

used for gout

forms a complex with tubulin dimers and copolmerizes into the microtubule lattic

62

Antimitotic Drugs 

 

Vinblastine

binds to the plus end of ictrotubles to suppress MT dyamics 

Treat: lymphomas (lymph and spleen tumors)

63

Antimitotic Drugs

 

Paclitaxel/ Taxol

binds on inside of microtubule prevents its depolymerization

 

Treats: breat and ovarian cancer

64

Microtubule arrangement 

 

Cilia

 

Basal Body

Cilia - (9+2) axoneme

Basal Body (9+0) same as centrioles

65

How are basal bodies attached to the cytoplasm?

Through straited rootlets

66

Moter Protiens Microtubules

Dynein

Dynein/dynactin

move chromosomes along kinetochore microtubules as microtubules shorten at hte kinetochore byt he loss of GDP-tubulin

67

Bardet-Biedil syndrome (BBS)

defective intraciliary and intraflagellar transport of axonemal protien

issue with dynein and kinesin

 

Clincial Correlates

age related retinal dystrophy

obesitiy

polydactyly (extra fingers)

renal malfucntion

reproductive tract abnormalities

learning disabilities

 

68

Cilia

protect the surface of epithelia from pathrogens (resp tract)

motile

mobilization of cells (oviduct-egg transport/ efferent ductules of epiddymis-sperm transport)

69

Primary Cilium

immotile

speicalized antenna_collects info from ECM to trigger cell signaling

modified primary cillia ( kinocilium-ear,haircells/ phtoreceptor cells-retina)

 

 

70

(Dsykinesia)

Defects in primary cilia formation

Left-right axis malformation

Situs inversus-heart on right side intestinal malrotation 

 this is because primary cilia generate a direction flow gradient of regulartory molecules (morphogens) to dictate correct organ development during embryogenesis

 

71

Function of hte inner sheath and radio spokes

stablization of axonemal bending

72

Issue with axonal transport

kartenger syndrome

73

movement

cilia vs. flagella

cillia-power stroke

flagella-sinsoidal movement 

74

Myosin I

(unconventional myosin)foudn in all cell types

 

one head domain and a tail

single light chain

interacts with actin filaments and contains ATPase 

transports vesicle of organelles

smaller then myosin II 

dont form dimers

75

Myosin II

(conventional myosin)

Present in muscle and non musucle cells

identical molecules

ATPase containing head domain longg rodlike tail

Muscle contraction

76

Myosin V

(unconventional)

double head with ATPase

RAb27a

vesicle receptor