Cytoskeleton

Question 1

Describe the cytoskeleton

Answer 1

Maintain cells shape, internal organisation, provides mechanical support for division/movement

Question 2

What are the functions of the cytoskeleton?

Answer 2

Maintain/change cell shape
Provides coordinated/directed movement - Motility, muscle contraction, cell division
Supports intracellular transport - Organelles, molecules
Maintains organelle distribution

Question 3

Describe the structure of the cytoskeleton

Answer 3

Microtubules (major part, in all EK cell)
Microfilaments
Intermediate filaments

Question 4

Describe the microtubules of the cytoskeleton

Answer 4

Involved in mitosis, cell motility, intracellular transport, maintenance of cell shape
Ends grow more quickly than neg end
Negative end is anchored to microtubule organising centre (MTOC)
Switch from growth to shrink = Catastrophe

Question 5

Describe the growth of microtubules

Answer 5

Rapidly grow via polymerisation/shrink via depolymerisation

Question 6

Describe the microtubule organising centres

Answer 6

Centromere = Primary MTOC
In dividing cells, important role for mitosis
In non-dividing cells, MTOC’s give basic organisation of cells positioning organelles in cyto

Question 7

Describe the dynamic instability of microtubules

Answer 7

Ability to grow/shrink rapidly in response to a cells needs

Growing/shrinking dependent upon - Tubulin conc, microtubule associated proteins

Question 8

Describe motor proteins

Answer 8

Walk along microtubule transporting a substance

Powered by hydrolysis of ATP

Question 9

Name structures containing MTs

Answer 9

Basal bodies, centrioles, cilia, flagella

Question 10

Describe microfilaments

Answer 10

Actin/myosin present in contractile cells (skeletal)

Question 11

Describe actin

Answer 11

In non-muscle cells, has long spiral chain of the same proteins, growth powered by ATP further growth occurs at positive end

Question 12

What is the function of microfilaments?

Answer 12

Determine cell surface shape, Control cell locomotion, Motor protein track for: Transport/Contraction

Question 13

Describe myosin

Answer 13

Moves cargo along microfilaments, provides force for muscle contraction

Question 14

Describe intermediate filaments

Answer 14

Resist stress/deformation, hold organelles in position/nuclear membrane - IF precursors transported by kinesin, dynein, myosin eg network communication

Question 15

What is spectrin?

Answer 15

Protein filament lines intracellular side of plasma membrane

Question 16

Describe spectrin tetramer

Answer 16

Composed of alpha and beta subunits
Maintains stability/structure of cell membrane
Flexible/strong contributes to cell adhesion/movement
Mutations of spectrin lead to many human diseases eg hereditary spherocytosis haemolytic anaemia