Cytoskeleton

Question 1

What are the main functions of the cytoskeleton?

Answer 1

• Cell movement
• Movement of organelles and genetic material
• Holding organelles in place

Question 2

What are microfilaments? What protein are they made from? What are they responsible for?

Answer 2

• Contractile fibres made from actin.
• Responsible for cell movement, and cell contraction during cytokinesis (invagination and the separation into 2 daughter cells).

Question 3

What are microtubules? What protein are they made from? What are they responsible for?

Answer 3

• Globular tubulin proteins polymerise to form tubes that form a scaffold-like structure.
• Determine the shape of the cell.
• Act as tracks for the movement of organelles, including vesicles, around the cell.
• Spindle fibres are composed of microtubules. So are centrioles and the centrosome.

Question 4

What are intermediate fibres?

Answer 4

• Give cells mechanical strength and help maintain their integrity.

Question 5

What are cilia made from? What is the difference between mobile and stationary cilia? What are there roles?

Answer 5

• Stationary cilia are present on the surface of many cells and have an important function in sensory organs such as the nose.
• Mobile cilia beat in a rhythmic manner, creating a current, causing fluids or objects adjacent to the cells to move. E.g in the trachea to move mucus, or in the fallopian tubes to move ova.
• Each cilium contains two central microtubules surrounded by nine pairs of microtubules arranged like a wheel. 9+2.

Question 6

What are the functions of flagella?

Answer 6

• Used primarily to enable cells motility. Sometimes used as a sensory organelle detecting chemical changes in the cell’s environment.
• Usually longer than cilia.