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HIstology > Epithelium: Cytoskeleton > Flashcards

Epithelium: Cytoskeleton Flashcards

1
Q

In the intestinal microvilli…Identify

What type of epithelia is present

left to right

Line 1

Line 2

A

Ciliated Columnar

Brush border

Goblet Cell

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2
Q

Intestine

Identify (left to right)

Line 1

Line 2

LIne 3

LIne 4

Bottom third

Left to right

Line 1

Line 2

A

Cap

Intestinal microvillus

Actin Bundle

Glycocalyx

Actinf ilament rootlets

Terminal Web

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3
Q

Microvilli and sterocillia have what type of core?

A

F-Actin

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4
Q

where are microvili found?

A

In the small intestine-brushborder (columnar)

and the kidney-nephron (cuboidal)

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5
Q

Microvilli serve what purpose?

A

to increase the absorbative surface

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6
Q

What protien is seen inside the cap of microvilli?

A

Formin(caps the barbed end)

promotes the enlongation of unbranched f-actin

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7
Q

How wide is f-actin?

A

7um

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8
Q

What are the actin cross linking protiens found in microvilli?

A

Villin

fimbrin

both stablize the actin bundle

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9
Q

What are the membrane linking protiens found in microvilil?

A

myson I and Calmodulin

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10
Q

What purpose does Glycocalyx serve and where is it found?

A

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

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11
Q

The terminal web is seen at the base of …

and what does it consist of?

A

Microvilli

it consist of IF and spectrin

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12
Q

What are the affects of cytochalsins on F-actin?

Where is it found

A

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

prevent addition of G-actin

Found in Fungi (alkoloids)

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13
Q

What are the effects of Phalloidin on F-actin?

A

It binds to actin filaments preventing their depolarization

foudn in mushrooms (alkoloid)

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14
Q

What are the effects of Latroneulins on F-actin?

A

Binds to G actin and induces F -actin depolarization

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15
Q

In microfilements Polymerzation is dependant on what?

A

ATP

Occurs at (+) barbed end

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16
Q

Profilin is a…

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

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17
Q

Gelsolin…

A

Severing/capping protien

binds to the newly formed plus end

Blocks further polymerization

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18
Q

Cofilin

A

Actin depolymzerzation factor

stimulates the dissasocation of ADP bound B actin

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19
Q

What is treadmilling?

Steps of Treadmilling

A

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 (-).
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20
Q

WASP is seen where?

What does it do?

A

In F-actin

it is a branching protien (activates ATP for branching)

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

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21
Q

WAS is due to a defect in

A

WASP

low latelet count

immunodeficiency

respiratory infections

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22
Q

F-Actin

Made out of..

Depend on what for assembly?

Moter protiens

State

A

G-actin

ATP-dependant

Double helical and BRanching

Treadmilling

Myosin Va/vIia (muscle contraction)

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23
Q

Actin filaments (microfilaments) are involved in ..

A

cell motility…and cargo stransport

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24
Q

Microtubles are involved in…

A

cell motility and cargo transport

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25
Q

intermediate filaments provide

A

mechanical strength

skin support

stability

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26
Q

Direct immunoflorescence

Adv

Disadv

A

adv: direct attachment of de to primary antibody

faster

disadv

less senstiive then indirect

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27
Q

Indirect immunofluorescence

A

Adv: uses two antibodies (more specfic)

Disadv: complex..time consuming

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28
Q

Limitations of Immunofluorescence Microscropy

A
  1. photobleaching
  2. limited to fixed cells/tissues (dead)

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

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29
Q

Identify type of cytoskelteon from left to right

A

Intermediat fil (10)

Microtubles (25)

Actinfilament bundle (7)

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30
Q
A
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31
Q

Where are intermediate filaments found?

A

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
Q

How are intermediate filaments formed?

A

1Monomer

  1. dimer (parallel arangment)
  2. tetramer (antiparallel arrangment +side by side)
  3. protofilament (tetramers align end to end)
  4. protofibril (protofilaments align side by side)
  5. intermeidate filaments (8 protofibrils wind up_
33
Q

What does phosphorylation do to Intermediate filaments?

A

diassemble

34
Q

What does dephosphorylation do to IF?

A

promote assembly

35
Q

Classification of IF

I/II

III

IV

V

IV

A

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
Q

Epidermolysis Bullosa Simples (EBS)…

A

defect in keratin

cant form strong IF

weak

blisters after minor trauma

37
Q

Excessive Keratinzation

A

skin becomes cracked for fragmented

38
Q

Keratin provides…to epithelial cells

A

mechanical strength

39
Q

Nuclear Lamina is associated to…

A

inner nuclear membrane

40
Q

What are the only organelles surround by a double membrane?

A

Mitocondria and Nucleus

41
Q

Nuclear Lamina contains

A

Lamins (type V IF)

42
Q

Lamins..

A

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

43
Q

Lamins are divided into Type A and Type B lamins

describe

A

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
Q

Structural alterations of Lamins …

A

impact integrity of the nucleus

nuclear fragility

decrease of gene expression

eventual nuclear destruction

45
Q

Laminopathies

A

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
Q

Microtubules are composed of

A

tublin dimers which polymerize in the presence of GTP

47
Q

Microtubules main function

A

cell division …and cargo transport

48
Q

Describe the structure of microtubules

A

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
Q

Microtubules grow out from

A

Centrosomes

50
Q

Microtubule motor protiens

A

Kinesin (anterograde)

dynein (retrograde)

51
Q

Microtubules can form transient and permenant structures..

A

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
Q

Microtubule associated protiens (MAPs)

A

facilitate assembly and prevent diassembly

53
Q

Centrosome

A

Function as microtubule orangizing center

minus ends of hte microtubules are anchored

54
Q

Types of microtubless (3)

A

kinetochore

Polar

Astrial (radiating)

55
Q

Mitotic Center (centrosome)

A

Microtuble organizing center

centrioles (2)

Radiating microtubules/ astrial (extend outward to cell periphery)

56
Q

Mitotic apparatus

A

centrosome (mitotic center)

+

spindle

57
Q

Mitotic spndle

A

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
Q

Centrosome

A

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
Q

Vocabulary

Kinetochore

A

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
Q

Vocabulary

Centromere

A

chromosomal site where the kinetochore assembles

narrow chromatin region on metaphase chromosomes

primary constiriction

61
Q

Antimitotic Drugs

Colchicine

A

TOXIC NOT USED IN TREATMENT OF TUMORS

used for gout

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

62
Q

Antimitotic Drugs

Vinblastine

A

binds to the plus end of ictrotubles to suppress MT dyamics

Treat: lymphomas (lymph and spleen tumors)

63
Q

Antimitotic Drugs

Paclitaxel/ Taxol

A

binds on inside of microtubule prevents its depolymerization

Treats: breat and ovarian cancer

64
Q

Microtubule arrangement

Cilia

Basal Body

A

Cilia - (9+2) axoneme

Basal Body (9+0) same as centrioles

65
Q

How are basal bodies attached to the cytoplasm?

A

Through straited rootlets

66
Q

Moter Protiens Microtubules

Dynein

A

Dynein/dynactin

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

67
Q

Bardet-Biedil syndrome (BBS)

A

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
Q

Cilia

A

protect the surface of epithelia from pathrogens (resp tract)

motile

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

69
Q

Primary Cilium

A

immotile

speicalized antenna_collects info from ECM to trigger cell signaling

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

70
Q

(Dsykinesia)

Defects in primary cilia formation

A

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
Q

Function of hte inner sheath and radio spokes

A

stablization of axonemal bending

72
Q

Issue with axonal transport

A

kartenger syndrome

73
Q

movement

cilia vs. flagella

A

cillia-power stroke

flagella-sinsoidal movement

74
Q

Myosin I

(unconventional myosin)foudn in all cell types

A

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
Q

Myosin II

(conventional myosin)

A

Present in muscle and non musucle cells

identical molecules

ATPase containing head domain longg rodlike tail

Muscle contraction

76
Q

Myosin V

(unconventional)

A

double head with ATPase

RAb27a

vesicle receptor

HIstology (17 decks)

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