Tissue Architecture Flashcards

1
Q

What are the 4 main characteristics of the cytoskeleton?

A

Dynamic
Adaptable
Stable
Strong

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2
Q

How are cytoskeletal filaments dynamic and adaptable?

A

Switch between their small soluble subunits and large filamentous polymers

Adapt by when they receive a signal they RAPIDLY disassemble and subunits diffuse to new site and reassemble

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3
Q

What property allow cytoskeletal filaments to be strong?

A

staggered long subunits= rope like properties
- less rigid because can twist and pull

Intermediate filaments do not have this characteristic

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4
Q

What are Intermediate Filaments made of? What are their roles?

A

Lamin, often anchored to plasma membrane at cell- cell junctions

Tensile strength –> withstand mechanical stress
- rope like properties and stabilization through cross linking by accessory proteins

Form network and surround nucleus

Nuclear lamina= underlies and strengthens nuclear envelope

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5
Q

What are the 2 classes of intermediate filaments?

A

Nuclear= nuclear lamins

Cytoplasmic= keratin filaments, vimentin (connective tissue), and neurofilaments

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6
Q

How can progeria arise?

A

Mutation in intermediate filaments causing increased cellular aging

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7
Q

What cytoskeletal filament is blistering of the skin associated with?

A

mutation in intermediate filament

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8
Q

What are Microtubules made of? What are their roles?

A

alpha,beta-tubulin heterodimer= subunit
- long hollow polar tube (+ end for growth - end for disassembly, rapid process)

Mitotic spindle for chromosome separation
Cilia and flagella parts
Centrosome –> cell peripherally so tracks for transport

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9
Q

What is the role of gamma-tubulin mircotubules?

A

Form nucleus that attaches to the (-) end of the microtubule serving as an anchoring point

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10
Q

How does the drug Taxol effect microtubules?

A

Binds and stabilizes microtubules which prevent chromosomal segregation –> cells stalled in M phase –> apoptosis

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11
Q

How do the drugs Cholchicine (colcemid) and Vinblastine (vincristine) effect microtubules?

A

stabilize monomers preventing polymerization –> slow cell division

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12
Q

What are Microfilaments made of? What are their roles?

A

G-actin –> F-actin polymer, polarity

instability allows them to play role in cell movement

  • locomotion, phagocytosis, cell division, contraction
  • stabilize when associate with other proteins
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13
Q

What is the action of the drug Phalloidin?

A

Bind and stabilize actin filaments

Use if eat death cap mushroom

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14
Q

What is the function of collagen in the basal lamina and connective tissue? What is its composition

A

Main structural protein

Trimeric proteins (homo or hetero trimers) form collangeous triple helix 
- associate as fibers, sheets, or transmembrane structures
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15
Q

What are the key steps of collagen synthesis?

A
  1. In RER preprocollagen synthesized –> procollagen molecule inserted in to the lumen of the ER
  2. Hydroxylation of proline and lysine residues, glycosylation of hydroxylysine residues
  3. Self-assembly of tropocollagen molecule, initiated by disulfide bond formation in c-terminal extensions= Triple helix formed
  4. Cleavage of propeptides, assembly into fibrils and fibers
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16
Q

What is scurvy?

A

Loss of Cofactor= Ascorbate or Iron

17
Q

What is Ehlers-Danlos Syndrome?

A

Mutation in collage or collagen synthesis genes

  • depending where mutation is in process there is different severity
  • weakens connective tissue in the skin bones vessels and organs
18
Q

What is the difference between cell junctions and focal contacts?

A
Junctions= link to neighboring cells
Focal= link cells to ECM or basil lamina 

Both have roles in migration, immune system, tissue architecture, signaling pathways

19
Q

What are the 3 domains of CAMs?

A

Extracellular= binding to adjacent cell/matrix proteins

Transmembrane= links CAm to membrane

Cytoplasmic= to cytoplasm via linker porteins

20
Q

Is the Cadherin Superfamily Ca2+ dependent or independent? What are examples of classic and atypical cadherins?

A

Ca2+ Dependent

Classic= E (epithelial), N (neural), VE (vascular endothelial)
- linked to actin cytoskeleton, associated with adherens junctions

atypical= T and LI (liver intestine)
- homophilic adhesion proteins without interaction with catenins or link to actin cytoskeleton

21
Q

What is the role of Cadherins in cancer?

A

epithelial to mesenchymal transition

- E-cadherin decrease, N cadherin increase –> invasiveness and metastasis

22
Q

Is the Ig Superfamily Ca2+ dependent or independent? What are examples?

A

Independent

ICAM, VCAM, PECAM, NCAM
- recognition binding or adhesion processes of cells

23
Q

Is the Selectins Superfamily Ca2+ dependent or independent? What are examples and what are their roles?

A

Dependent

Bind to extracellular carbohydrates
Host defense mechanism
- allows for rolling during leukocyte adhesion cascade

E-selectin (endothelial), L-selectin (leukocyte), P-selectin (platelet)

24
Q

What is the role of Integrins?

A

Couple extracellular matrix to cell cytoskeleton

Activate signaling pathways

Cell-cell interactions via B2 family= on leukocytes allow for adhesion and transmigration to sites of infection

25
What is the structure and function of anchoring junctions?
Attached to components of the extracellular matrix and anchored to one another - keeps cells together and in the structural cohesion of tissues
26
What is the structure and function of occluding junctions?
Tight junction Prevent leakage of transported solutes and water and seals off body cavities from blood - more strands less ions passed
27
What is the structure and function of channel-forming junctions?
Gap junction Directly connect the cytoplasm of two cells, which allows various molecules, ions and electrical impulses to directly pass through a regulated gate between cells - composed of 2 connexons - regulated by pH or Ca2+
28
What is the structure and function of signal relaying?
Chemical synapses in nervous system