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HIstology > Epithelium: Cytoskeleton > Flashcards

Epithelium: Cytoskeleton Flashcards

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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
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
Intermediat fil (10) Microtubles (25) Actinfilament bundle (7)
30
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 deficienc*y 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

HIstology (17 decks)

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