0303 Cell Biology 2

Question 1

What is the cytoskeleton of the cell and what are it’s functions

Answer 1

The cytoskeleton is a network of microfilaments and microtubules inside the cell. It maintains cell shape, provides intracellular motility and locotmotion of the cell itself

Question 2

What are the 3 types of microfilaments and how are they differentiated

Answer 2

The 3 types of microfilaments are thin, intermediate and thick filaments. They are mainly distinguished by their diameters

Question 3

What are thin filaments made of? Give an example of where you would find thin filaments

Answer 3

Thin filaments are primarily made of actin. They can be found in the ectoplasm ( a layer of actin below the plasmalemma which supports the membrane)

Question 4

List one example of of intermediate filaments and where you might find them

Answer 4

Lamins are a type of intermediate filament and can be found in the internal lamina of a cell’s nucleus

Question 5

What ar e thick filaments made of ? What function do they provide

Answer 5

Thick filaments are made of Myosin. They’re primary function is movement of the cell and motility

Question 6

What are microtubules? What are they made of and give an example of microtubules in the cell

Answer 6

Microtubules are hollow cylinders of tubulin (protein). They exist in 2 isoforms (alpha and beta) and can be foudn int he centrioles and mitotic spindles during cell division

Question 7

List the 3 types of cellular motion

Answer 7

Cilia movement, pseudopod movement and specialised muscle cell movement

Question 8

What are motile cilia? What is their function and where are they found

Answer 8

Cilia are small, elongated, projections with microtubule skeletons. They function to move particles via continuous and synchronous beating. They can be found in the fallopian tube and the respiratory tract

Question 9

What are pseudopodia? What is their function? Give an example of pseudopod movement

Answer 9

A pseudopod is a cytoplasmic projection of an amoeba. Pseudopods allow movement by probing in a desired direction which is subsequently followed by the rest of the cytoplasm. An example of pseudopod movement is white blood cells towards a infected area

Question 10

List the mechanisms compounds use to move in and out of a cell (there are 5)

Answer 10

Diffusion, Carrier proteins , Channel proteins, Membrane invagination and Exocytosis

Question 11

List the 3 types of membrane invagination

Answer 11

Pinocytosis (cell drinnking), Calthrin mediated endocytosis (cell pinching) and Phagocytosis (cell eating)

Question 12

Describe the process of pinocytosis

Answer 12

Very small portions of the membrane are pinched off into the cytoplasm. The vesicle contains extracellular liquid + solutes. The process is energy dependant (GTP-ase and protein involved called dynamin).

Question 13

Describe the clathrin dependent endocytosis

Answer 13

Cell internalizing molecules via inward budding of membrane. Ligand binds to receptor protein on membrane. Receptor + ligand is opsonised in clathrin coated pit. Clathrin uncoats vesicle which is ready to fuse and release contents. However the fate of the vesicle can vary

Question 14

Describe the process of phagocytosis

Answer 14

Unbound phagocyte surface receptors do not trigger phagocytosis. Binding of ligands to receptors causes them to cluster. Phagocytosis is triggered and the particle is taken up by the phagocyte

Question 15

Describe the process of exocytosis

Answer 15

proteins synthesised in ribosomes and packaged in GA are packed into vesicles. Vesicles move towards cell surface. When the vesicles are to be discharged, vesicle membrane fuses with plasmalemma which releases contents

Question 16

What are the 2 types of exocytosis

Answer 16

Constitutive exocytosis ( constant release of vesicles) and regulated exocytosis (granules accumulate near surface and exit cell when stimulated e.g. CA2++)

Question 17

How does intra cell traffic (vesicles, granules, etc) guided to the cell membrane

Answer 17

Movement of cytoplasmic traffic is governed by the presence of surface proteins on the vesicle membrane. If the vesicle originates from the golgi they are coatomeres. If it comes from endocytosis there are called snares