Vesicular Transport

Question 1

How Do Small molecules travel across the membrane?

Answer 1

Water and small molecules enter and leave the cell by passing through the lipid bilayer of the cell membrane.

Passing through means of passive transport, active transport.

Question 2

What protein is involved in facilitated diffusion?

Answer 2

Channel proteins

Question 3

How do Large molecules travel across the membrane?

Answer 3

Proteins and polysaccharides and larger particles across the membrane using Vesicles.

Question 4

REMEMBER!!!!

Answer 4

The membranes of organelles communicate with each other through fusion of the vesicles.

Question 5

Two Key processes of vesicular transport

Answer 5

Exocytosis
Endocytosis

Question 6

Exocytosis

Answer 6

Secretions of macromolecules through fusion of vesicles with the plasma membrane.

Question 7

Endocytosis

Answer 7

Cell takes in macromolecules by forming new vesicles from the plasma membrane.

Question 8

Budding & Fusion

Answer 8

Budding from donor
Fusion with target
Membrane is transferred
Proteins retain original configuration
Soluble components transferred

Question 9

vesicles

Answer 9

Form part of the endomembrane system.

Small membrane-bound sac.

Transport or store substances.

Vesicles can fuse with organelles to release their contents within the cell.

Vesicles can also fuse with the cell/plasma membrane and release their contents outside of the cell.

Question 10

types of vesicles

Answer 10

Vacuoles
Lysosomes
Peroxisomes
Endosomes
Transport vesicles
Secretory vesicles

Question 11

Two types of Exocytosis

Answer 11

Constitutive Exocytosis
Regulated Exocytosis

Question 12

Constitutive exocytosis

Answer 12

steady stream of transport vesicles from trans Golgi to plasma membrane.
New lipids and proteins are continuously supplied to the plasma membrane for membrane growth, rejuvenation and remodelling.

Question 13

Regulated exocytosis

Answer 13

Functions only in cells specialised for secretion.
Lots of secretory vesicles found in specialised secretory cells — hormones, mucous, digestive enzymes.
Extracellular signal will stimulate their fusion with the plasma membrane and release into the extracellular fluid.

Question 14

Three Types of Endocytosis

Answer 14

Phagocytosis
Pinocytosis
Receptor-Mediated Endocytosis

Question 15

Phagocytosis

Answer 15

is engulfment of a particle, usually food or microorganisms, by wrapping cell membrane around it to form a vacuole. Known as Cellular eating!!

The particle is digested after the vacuole fuses with a lysosome containing hydrolytic enzymes.

Protozoa use phagocytosis to feed.
Macrophages defend against microorganisms.
Macrophages/cleaner cells - engulf old RBCs.

Amoeba use phagocytosis to feed !!!

Question 16

Pinocytosis

Answer 16

is the same process except that fluids are taken into small vesicles. Known as Cellular drinking!!

Question 17

Receptor-Mediated Endocytosis

Answer 17

is where receptors in a receptor-coated pit interact with a specific protein, initiating formation of a vesicle.

Question 18

ligands

Answer 18

extracellular substances

Question 19

3 Types of Coated Vesicles

Answer 19

CLATHRIN
COP I
COP II

Question 20

CLATHRIN

Answer 20

A protein, a ‘triskelion’ comprised of 3 light chains and 3 heavy chains.

Clathrin coated vesicle traffic between the Golgi network and the lysosomes; and between the plasma membrane and the endosomes.

Question 21

Triskelion

Answer 21

Comprised of 3 light chains and 3 heavy chains.

Triskelions form a framework of hexagons and pentagons to form coated pits on the membrane surface.

Question 22

Formation of a Clathrin coated vesicle

Answer 22

1. Molecules bind to surface receptors of the plasma membrane proteins located in area of clathrin-coated pits.
2. Pits bud to form clathrin-coated vesicles.
3. Fusion with endosomes or lysosomes.

Question 23

Endosomes

Answer 23

appear as a complex set of connected membranes tubes and larger vesicles.

Acidic environment promotes cargo release

Question 24

two populations of endosomes:

Answer 24

Early endosomes (beneath plasma membrane)

Late endosomes (near nucleus)

Question 25

Endosome

Answer 25

main sorting station in the endocytic pathway