cytoskeleton

Question 1

What is the cytoskeleton ?

Answer 1

• Present in the cytoplasm which consists of cytosol, organelles and the cytoskeleton.
• Dynamic meaning its constantly moving, allowing it to respond to changes and carry out its function.
• only present in eukaryotic cells
• network of fibres

Question 2

Made up of 3 protein fibres

Answer 2

• microfilaments
• microtubules
• intermediate fibres

Question 3

Roles of the cytoskeleton

Answer 3

• whole cell support
• mechanical strength
• formation/ movement of cilia
• cell movement eg, exocytosis, phagocytosis and cytokinesis
• movement of organelles
• movement of genetic material

Question 4

structure of microfilaments

Answer 4

• small solid strands
• about 7 nm in diameter
• fibres are contractile
• formed by the protein actin

Question 5

microfilaments functions

Answer 5

• actin important in muscle contraction
• responsible for cell movement and cell contraction during cytokinesis
• involved in phagocytosis

Question 6

Micro tubules structure

Answer 6

• tiny protein cylinders, straight and hollow
• around 18-30 nm in diameter
• Globular tubulin proteins polymerise to from tubes which form scaffold like structures which determines the shape of the cell

Question 7

Micro tubules function

Answer 7

• acts as tracks for the movement of organelles, including vesicles, around the cell.
• motor proteins walk vesicles along microtubules
• spindle fibres are composed of microtubules
• centrioles, made of micro tubules
• cilia and undulipodia are composed of microtubules

Question 8

Micro tubules function movement

Answer 8

• cellular movement is accomplished by cilia and undulipodia

Question 9

What are cilia ?

Answer 9

• cilia are hair like structures,
• can beat in synchrony, causing movement.
• found in lining of trachea and tubes of female oviduct
• have a 9+ 2 arrangement

Question 10

What are undulipodia

Answer 10

• whip like appendages that undulate to move cells.
• longer than cilia
• similar internal structure to microtubules
• found on sperm cells
• have a 9+2 arrangement

Question 11

intermediate filaments structure and function

Answer 11

• 10 nm in diameter
• give mechanical strength to cells to help maintain their integrity

Question 12

What are motor proteins

Answer 12

• molecular motors that use the cytoskeleton to move along the cytoplasm of the cell.

Question 13

What is myosin

Answer 13

• a cytoskeletal motor protein for micro filimants
• allows muscle contraction when interacts with actin

Question 14

What is dynein ?

Answer 14

• cytoskeleton protein
• allows cilia/ undulipodia movement when interacts with tubulin

Question 15

Defective dynein causes

Answer 15

• male infertility
• leads to respiratory tract ans sinus problems

Question 16

what is kinesin?

Answer 16

• motor protein
• moves vesicles when interacts with tubulin