Intercellular Connections Flashcards

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1
Q

Intercellular Connections

A

Neighboring cells often adhere, interact, and communicate via sites of direct physical contact

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2
Q

Intercellular Connections in ANIMALS

A

1) Gap Junctions
2) Tunneling Nanotubules (TNTs)
3) Desmosomes
4) Tight Junctions

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3
Q

Intercellular Connections in PLANTS

A

Plasmodesmata

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4
Q

Gap Junctions

A

Connects the outside of two cells AND their cytoplasm

–>Physically tethers the cells together

(A cytoplasmic channel between two cells)

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5
Q

Gap Junctions Composition

A

Made up of 2 connexons (one from each interacting cell)

–> Cytoplasmic channel = hydrophilic
–> Outside of junction = hydrophobic

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6
Q

Connexon

A

Made up of 6 connexin proteins (alpha helix proteins)

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7
Q

Gap junctions “open” when ________

A

2 connexons interact

(junction is “closed” when there is only one connexon)

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8
Q

Do things pass through gap junctions?

A

YES –> Mainly polar or charged molecules as the channel is hydrophilic

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9
Q

Tight Junctions

A

Areas where membranes of adjacent cells are FUSED

–> Creates ONE single SHARED membrane in the region of the junction

–> Tethers cells together

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10
Q

Do things pass through tight junctions?

A

NO: Tight junctions are IMPERMEABLE

–> They form a continuous seal around the cells

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11
Q

Tight junctions prevent…

A

leakage of any cell content through the membranes

(establishes a barrier to prevent anything from moving across a layer of cells)

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12
Q

Tight junctions are like…

A

Button snaps on a jacket

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13
Q

Tight junctions between cells in the bladder…

A

prevent the leakage of urine out of the bladder –> Keeps it contained through the watertight seal created between the epithelial cells

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14
Q

Tight junctions are similar to but STRONGER than…

A

desmosomes

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15
Q

Desmosomes

A

Anchor adjacent cells together

–> Impermeable junctions

–> Fastens cells together in “strong sheets”

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16
Q

Desmosome composition

A

Cells are anchored together through LINKER PROTEINS on the cell surfaces

Intermediate Filaments anchor the desmosomes in the cytoplasm

17
Q

Desmosomes serve what purpose in muscle cells?

A

Attach muscle cells to produce muscle tissue

18
Q

Tunneling Nanotubules

A

TNTs: Actin driven protrusion that extends from one cells to a target cell which then fuses with the target cell’s membrane

–> Creates cytoplasmic bridge: allows for passage of materials between cells

19
Q

TNT Cytoplasmic Bridge Composition

A

1) Contains a shared cytoplasmic region

2) Contains a filamentous actin (F-actin) running through the middle of it

–> Allows molecules to move through the nanotubule using motor proteins

20
Q

Plasmodesmata

A

Channels that connect plant cells together

–> Cytoplasmic connections (channels) THROUGH cell walls

21
Q

Layers of Plant Cell Wall System

A

Outer to inner:
1) Primary cell wall (wall cell was “born” with)
2) Secondary cell wall (Inner wall)
3) Cell membrane
4) Cytosol

22
Q

Primary Cell Wall

A

The outer layer of the cell wall
–> Plant was “born with it”

23
Q

Secondary Cell Wall

A

The inner layer of the cell wall
–> Created “after birth” of cell

24
Q

Middle Lamella

A

Space between plant cells

25
Q

Plasmodesmata unifies…

A

most of the plant into one living continuum

–> The cytoplasm is continuous between cells connected with plasmodesmata

–> The ER is also continuous

26
Q

Plasmodesmata also contains…

A

The ER

–> ER from one cell connects to the ER from another cell through the plasmodesmata

–> Creates one continuous ER system

27
Q

2 states of plasmodesmata are:

A

Normal State = Smaller molecular transport (“more closed”)

Enlarged State = Larger molecular transport (“more open”)