Cell communication (Vesicular transport) and extracellular matrix

Question 1

describe the two types of cell communication

Answer 1

transport / trafficking (vesicular)
- physical movement of proteins and lips within the cell

signalling
- transport of a specific signal received from outside to elicit a cellular response

** two types work together. Not seperate from each other. they influence each other

Question 2

Descrive Vesicular transport and the 3 types.

Answer 2

1 endocytosis 
- materials move into cell in vesicle formed form plasma membrane 
- require energy supplied by ATP 
- 3 types. 
receptor mediated endocytosis 
phagocytosis 
bulk-phase endocytosis (pinocytosis)

2 exocytosis

• materials move out of a cell by the fusion with plasma membrane of vesicles formed inside the cell
• require energy supplied by ATP

3 Transcytosis
- vesicles undergo endocytosis on one side of cell and undergo exocytosis on other

Question 3

Describe the 6 parts of receptor mediated endocytosis

Answer 3

1 Binding
- ligand binds to specific receptor in plasma membrane to form a ligand/ receptor complex

2 Vesicle formation
- edges of membrane fuse.
small piece of membrane pieces off.
results in coated vesicle that contains complex

3 Uncoating
vesicle becomes uncoated

4 Fusion with endosom
vesicle fuses with an endoscope. complex separates

5 Recycling of receptor to plasma membrane
receptors transport via transport vesicle to plasma membrane

6 Degrading in lysosomes
transport vesicles containing the ligand bud off then fuse with lysosome (contains digestive enzymes).
where molecules are broken down and recycled

Question 4

Describe phagocytosis

Answer 4

process in which a cell (phagocyte) engulfs large, solid particles (microbe).
digests it and exiles waste product

Question 5

describe the 3 steps involved in phagocytosis

Answer 5

1 - microbe ingested by phagocyte. results in formation of phagosome

2 - fusion of lysosome with phagosome

3 - microbe is broken down by the digestive enzymes

Question 6

describe bulk-phase endocytosis (pinocytosis)

Answer 6

process in which tiny droplets of ECF are taken into a cell

Question 7

describe the 3 steps involved with bulk-phase endocytosis (pinocytosis)

Answer 7

1 - plasma membrane folds inward and forms a vesicle containing a droplet of ECF that contains dissolves solutes

2 - vesicles detaches from plasma membrane and fuses with a lysosome

3 - enzymes degrade the solutes that then exit the lysosome to be recycled

Question 8

describe exocytosis

Answer 8

Process in which membrane enclosed vesicles (secretory) form inside the cell, fuse with the plasma membrane and release the contents (e.g neurotransmitters, hormones) into the ECF

Question 9

what are the two types of exocytosis?

describe.

Answer 9

1 - constitutive
when the molecules secreted in needed in constant levels (e.g albumin for extracellular matrix)

2 - regulated
the protein is secreted in response to a stimulus therefore it is secreted only when needed (GLUT receptors)

Question 10

Describe regulated exocytosis of glucose transporter

Answer 10

Glucose transporter is not needed until there is glucose in the blood. It’s stored in vesicles in cell until stimulus (insulin and insulin receptor) signals transporter is needed to take up glucose
once completed transporter endocytose back to vesicles inside cells

Question 11

Describe steps related to transcytosis

Answer 11

macromolecules contained in vesicles entry the cell via endocytosis, move across the cell and exit the same cell by exocytosis

occurs most commonly across endothelial cells that line blood vessels

during pregnancy, antibodies (IgG) cross the placenta into foetal circulation

delivery of IgA to the mucosal surfaces of respiratory, gastrointestinal & urogenital tracts nd export to milk