lecture 6 - cell shape regulation Flashcards

1
Q

How is the cytoskeleton dynamic?

A

The components of the cytoskeleton are cosntantly assembling and disassembling to rapidly change the shape of the cell.

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2
Q

Roles+properties of the cell cytoskeleton

A

CDOS - clever doctors observe skeletons
Cytoskeleton:
Dynamic
Position Organelles
Cell shape

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3
Q

What are the three components of the cytoskeleton that provide structure?

A

Microtubules, Microfilaments, Intermediate filaments

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4
Q

Summary mnemonic for structure and function of microtubules

A
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5
Q

What are microtubules made up of?

A

Tubulin subunits (dimers) in a twisted helix tube.

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6
Q

What do microtubules radiate out from? And the 2 organelles?

A

Micrtubule organising centres, Basal body , centrosome

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7
Q

What are centrosomes?

A

An organising centre, that is sometimes surrounded by microtubules, e.g. during the formation of the mitotic spindle

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8
Q

What type cytoskeleton component best resists compression?

A

microtubules

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9
Q

What structures create cell motility?

A

Flagella and cilia

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10
Q

What are the cytoplasmic components of flagella and cilia?

A

Microtubules

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11
Q

What is the role of cilia in a fixed cell?

A

The cilia beat back and forth, moving fluid/mucous past.

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12
Q

What is the structure of microfilaments?

A

Double chains of actin subunits that twist around each other.

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13
Q

Actin is the component of what cytoplasmic structural component?

A

Microfilaments

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14
Q

What structures can microfilaments form?

A

linear strands and 3D networks

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15
Q

What is required to allow microfilaments to branch?

A

branching proteins

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16
Q

How do microfilaments make the cell rigid?

A

They form a cortical network which replaces fluid in the cytoplasm, stiffening the cell.

17
Q

How do microfilaments aid in cell movement?

A

Actin in the microfilaments interacts with motor proteins to facilitate movement.

18
Q

What do Actin-Myosin interactions allow?

A

Muscle contraction, amoeboid movement, cytoplasmic streaming (in plants).

19
Q

How are intermediate filaments structured?

A

proteins are supercoiled into tight ‘cables’

20
Q

What is the least dynamic cytoplasm tubule/filament?

A

Intermediate filaments.

21
Q

What aids in maintaining structure in dead cells, such as hair and skin?

A

Intermediate filaments.

22
Q

What are the 3 major cell junction types?

A

Tight junctions, desmosomes, gap junctions

23
Q

What are tight junctions?

A

Junctions that press neighbouring cells close together, creating a continuous seal that prevents the movement of fluid between layers of cells.

24
Q

What are desmosomes?

A

Anchoring cell junctions that attach cells in sheets.

25
Q

What form of cell junctions are prevelant in muscle tissue?

A

Desmosomes

26
Q

What connects desmosomes into the cell?

A

Intermediate filaments

27
Q

What are gap junctions?

A

A point of cytoplasmic contact between two cells that allows ions and small molecules to move between cell cytoplasms via protein bridges.

28
Q

What cell junction allows for rapid intercellular communication?

A

Gap junctions

29
Q

Where do the materials of the extracellular matrix come from?

A

The are secreted from the cell via consituitive exocytosis.

30
Q

What is the most common category of proteins in the ECM?

A

Glycoproteins.

31
Q

What are glycoproteins?

A

Proteins with added carbohydrate groups.

32
Q

What is the most abundant protein in the extracellular matrix?

A

Collagen

33
Q

What are collagen fibres in the extracellular matrix embedded in?

A

Proteoglycans.

34
Q

What are proteoglycans?

A

Proteins with extensive sugar additions that exist in the extracellular matrix, embedded with collagen.

35
Q

What component of the ECM allows it to resist compression? And how?

A

Proteoglycans - They trap water, which resists breakage when compressed.

36
Q

What are fibronectins?

A

Glycoproteins that attach cells to components of the ECM.

37
Q

What are integrins?

A

Membrane proteins that connect the ECM to the cytoskeleton, allowing them to communicate.

38
Q

What is the most dynamic cytoplasmic protein structure?

A

Actin (microfilaments)