lecture 6 - cell shape regulation

Question 1

How is the cytoskeleton dynamic?

Answer 1

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

Question 2

Roles+properties of the cell cytoskeleton

Answer 2

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

Question 3

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

Answer 3

Microtubules, Microfilaments, Intermediate filaments

Question 4

Summary mnemonic for structure and function of microtubules

Question 5

What are microtubules made up of?

Answer 5

Tubulin subunits (dimers) in a twisted helix tube.

Question 6

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

Answer 6

Micrtubule organising centres, Basal body , centrosome

Question 7

What are centrosomes?

Answer 7

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

Question 8

What type cytoskeleton component best resists compression?

Answer 8

microtubules

Question 9

What structures create cell motility?

Answer 9

Flagella and cilia

Question 10

What are the cytoplasmic components of flagella and cilia?

Answer 10

Microtubules

Question 11

What is the role of cilia in a fixed cell?

Answer 11

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

Question 12

What is the structure of microfilaments?

Answer 12

Double chains of actin subunits that twist around each other.

Question 13

Actin is the component of what cytoplasmic structural component?

Answer 13

Microfilaments

Question 14

What structures can microfilaments form?

Answer 14

linear strands and 3D networks

Question 15

What is required to allow microfilaments to branch?

Answer 15

branching proteins

Question 16

How do microfilaments make the cell rigid?

Answer 16

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

Question 17

How do microfilaments aid in cell movement?

Answer 17

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

Question 18

What do Actin-Myosin interactions allow?

Answer 18

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

Question 19

How are intermediate filaments structured?

Answer 19

proteins are supercoiled into tight ‘cables’

Question 20

What is the least dynamic cytoplasm tubule/filament?

Answer 20

Intermediate filaments.

Question 21

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

Answer 21

Intermediate filaments.

Question 22

What are the 3 major cell junction types?

Answer 22

Tight junctions, desmosomes, gap junctions

Question 23

What are tight junctions?

Answer 23

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

Question 24

What are desmosomes?

Answer 24

Anchoring cell junctions that attach cells in sheets.

Question 25

What form of cell junctions are prevelant in muscle tissue?

Answer 25

Desmosomes

Question 26

What connects desmosomes into the cell?

Answer 26

Intermediate filaments

Question 27

What are gap junctions?

Answer 27

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

Question 28

What cell junction allows for rapid intercellular communication?

Answer 28

Gap junctions

Question 29

Where do the materials of the extracellular matrix come from?

Answer 29

The are secreted from the cell via consituitive exocytosis.

Question 30

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

Answer 30

Glycoproteins.

Question 31

What are glycoproteins?

Answer 31

Proteins with added carbohydrate groups.

Question 32

What is the most abundant protein in the extracellular matrix?

Answer 32

Collagen

Question 33

What are collagen fibres in the extracellular matrix embedded in?

Answer 33

Proteoglycans.

Question 34

What are proteoglycans?

Answer 34

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

Question 35

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

Answer 35

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

Question 36

What are fibronectins?

Answer 36

Glycoproteins that attach cells to components of the ECM.

Question 37

What are integrins?

Answer 37

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

Question 38

What is the most dynamic cytoplasmic protein structure?

Answer 38

Actin (microfilaments)