L24 Cell-Cell Junctions Flashcards

1
Q

What are Adherens junctions?

A

They are protein complexes which play a crucial role on cell to cell adhesion and tissue organisation.

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2
Q

Name an adherent junction protein?

A

Cadherins.

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3
Q

What type of adhesion does cadherins do?

A

Ca2+ dependent adhesion.

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4
Q

What are the features of adherens junctions?

A
  1. Homophilic interaction.
  2. Makes strong links between cells.
  3. Links to actin cytoskeleton.
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5
Q

What are the actin linked junctions?

A

Adherens junction and focal adhesion.

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6
Q

What is the adhesion belt in morphogenesis?

A

Cadherin - Catenin - Actin - Myosin.

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7
Q

What does focal adhesion and adherens junction link to?

A

They link to the actin cytoskeleton.

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8
Q

What are desmosomes and hemidesmosomes?

A

They both are important cell junction which contributes to cell integrity and structure, where desmosomes form cell to cell junctions and hemidesmosome form cell to extracellular matrix junctions.

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9
Q

What are tight junctions?

A

They are specialized regions of contact between endothelial and epithelial cells forming a semi permeable barrier.

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10
Q

What is the role of tight junctions and where is it located?

A

Location - Epithelia
Roles
1.Prevent fluid, ion and membrane flow.
2.Variable extent
3.Transcellular transport
4.Paracellular transport

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11
Q

How is the sealing strands formed in tight junctions?

A

By ridges of transmembrane particles

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12
Q

Name and state the function of tight junction proteins?

A

Zonula occludens proteins bind claudin, occludin and actin

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13
Q

Define membrane compartments.

A
  • Lipids And Proteins Segregated
  • Apical Outer Membrane:
    Glycolipid
    Cholesterol
  • Basolateral:
    Phosphatidylcholine
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14
Q

What is the length of gap junctions?

A

100 - 500 nm long

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15
Q

Where are the gap junctions distributed to?

A

Connective tissue, epithelia, neurons, heart muscle

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16
Q

What are the functions of gap junctions?

A
  • Allows regulated and direct cell-cell communication
  • Form 1.5 nm diameter pores
  • Water, inorganic ions, sugars, amino acids, ATP, cAMP, IP3
17
Q

What are gap junctions made up of?

A

Connexins

18
Q

How are gap junctions regulated?

A

Through membrane potential, ph, Ca2+ and cell signals

19
Q
A