Cytoskeleton

Question 1

What is the cytoskeleton and the three filamentous structures that compose it

Answer 1

Question 2

What are the functions of cytoskeletal components

Answer 2

Question 3

What are intermediate filaments

Answer 3

Question 4

What are the 4 major classes of intermediate filaments

Answer 4

Question 5

Describe keratin containing intermediate filaments

Answer 5

Question 6

Describe neurofilaments

Answer 6

Question 7

Explain IF assembly and disassembly

Answer 7

Question 8

What are IF linker proteins

Answer 8

Question 9

Describe actin filament structure

Answer 9

Question 10

Explain actin filament assembly and disassembly

Answer 10

Actin filaments can grow by the addition of monomers at either end, but their rate of growth is faster at the plus end (10 times) than at the minus end.
▪ Before it is incorporated into a filament, an actin monomer binds an ATP molecule, and therefore, Actin is an ATPase.
▪ The initial nucleation event in filament formation occurs slowly in vitro, whereas the subsequent stage of filament elongation occurs much more rapidly.
▪ The ATP associated with the actin monomer is hydrolyzed to ADP at some time after it is incorporated into the end of a growing filament.

Question 11

What is the function of actin filament assembly and disassembly

Answer 11

By controlling the assembly/disassembly, the cell can rapidly reorganize its actin
cytoskeleton when and where is needed for dynamic processes such as:
✓cell locomotion
✓changes in cell shape
✓phagocytosis
✓Cytokinesis
▪ Assembly/disassembly rate can be influenced by several actin-binding proteins

Question 12

What are acting binding proteins

Answer 12

Question 13

Describe cell motility (crawling)

Answer 13

Question 14

What are myosins

Answer 14

Question 15

Describe myosin I

Answer 15

Question 16

Describe myosin II

Answer 16

Question 17

How does F actin and Myosin II interact

Answer 17

Question 18

Describe muscle organization

Answer 18

Question 19

Explain muscle contraction of the sliding filament model

Answer 19

Question 20

What are microtubules

Answer 20

✓ Determine cell shape
✓ Position membrane-enclosed organelles within the cell
✓ Provide tracks for vesicles and organelle transport within a cell
✓Involved in mitotic spindles formation and cell division

Question 21

Describe the structure and composition of microtubules

Answer 21

Question 22

What are centrosomes

Answer 22

Question 23

What are the dynamic properties of microtubules

Answer 23

Question 24

Explain microtubule assembly (growth) and disassembly (shrinking)

Answer 24

Question 25

What are the microtubule-associated proteins

Answer 25

Question 26

Describe microtubule function in intracellular motility

Answer 26

Question 27

How do motor proteins traverse the microtubular cytoskeleton

Answer 27

▪ Motor proteins convert chemical energy (stored in ATP) into mechanical energy, to generate force to, for example, move cellular cargo. ▪ Microtubules and actin filaments serve as tracks for a variety of motor proteins that generate forces required to efficiently move objects within a cell. Motor proteins: ▪ Can be grouped into three broad superfamilies: * Kinesin and Dynein which move along microtubules * Myosin which moves along the actin filaments ▪ Move unidirectionally along their cytoskeletal track in a stepwise manner from one binding site to the next

Question 28

How do microtubules provide support and organization

Answer 28

Question 29

Describe kinesin-mediated organelle transport

Answer 29

Question 30

Describe basal bodies

Answer 30

Question 31

Describe the structure of eukaryotic cilia and flagella

Answer 31

▪ cilia and flagella share a similar internal structure (Axoneme). ▪ Axoneme: * Is the core of the cilium/flagellum * Contains an array of microtubules that runs longitudinally through the entire organelle * The axoneme of a motile cilium or flagellum consists of nine peripheral doublet microtubules surrounding a central pair of single microtubules (known as the 9 + 2 array)

Question 32

Explain the mechanism of ciliary and flagellar locomotion

Answer 32

▪ Because of the multiple links that hold the adjacent microtubule doublets together, the sliding force between adjacent microtubules is converted to a bending motion ▪ Other ciliary components control dynein activity leading to the complex wave seen in cilia and flagella