exocytosis and endocytosis

Question 1

what are the functions of the ER

Answer 1

protein biosynthesis (rough)
lipid biosynthesis (smooth)
intracellular Ca2+ store

Question 2

describe the structure of the ER

Answer 2

tubules and sacs developed from nuclear outer membranes
has a lumen

Question 3

how does the ER undergo post translational modification

Answer 3

form disulphide bonds
proper folding
addition of carbohydrates
specificic cleaving
assemble multimeric proteins to be sent to Golgi

Question 4

what are the different layers within the golgi apparatus

Answer 4

Cis Golgi Network:
Cis Cisterna
Medial Cisterna
Trans Cisterna

Trans Golgi Network

Question 5

what are the different functions of the golgi

Answer 5

carbohydrate synthesis
post translational protein and lipid modification: phosphorylation, sulphation, glycosylation
ER product sorting for exocytosis

Question 6

which cells have many golgi

Answer 6

secretory ex) goblet

Question 7

what is an early endosome

Answer 7

organelle (vesicle) that receives substances form endocytosis

Question 8

how can early endosomes become late endosomes

Answer 8

fuse with each other
early fuses with late

Question 9

where are early endosomes found

Answer 9

under the plasma membrane

Question 10

where are late endosomes found

Answer 10

near the nucleus

Question 11

what is the function of a late endosome

Answer 11

sorting compartement for endocytic substances
ex) receptors recycles to membrane or lysosomes or a different domain of the membrane depending on their adresses

Question 12

what is the function of a lysosome

Answer 12

digestion of products (recycling)
contains digestive enzymes for acid hydrolysis

Question 13

describe the process of vesicle transport

Answer 13

• cargo molecules bind to -transmebranous receptors in the donor membrane
• curved coat proteins bind to cargo and dissociates membrane and forms a bud
• Dyamin released vesicles (pinches off)
• vesicles will uncoat and travel to recipient membrane idenitfies by
• surface markers (V snares) that are complementry to target membrane (t snares)
• the v and t snares wrap around each other to form a trans snare complex which locks the membrane together, locking and fusing the membranes

Question 14

which curved coat protein is used for transport between the ER and Golgi

Answer 14

COPII

Question 15

What do snares mediated

Answer 15

homolytic fusion of vesicles

Question 16

how to Vesicular Tubular Clusters get to the golgi

Answer 16

move along microtubules by dyneins

Question 17

what are the different pathways in exocytosis

Answer 17

• constitutive secretory pathway - trans golgi apparatus to the plasma membrane
  no signals required

regulated secretory pathway
for specialises secretory cells like hormones, neurotransmitters, enzymes

Question 18

how are non protein molecules secreted
ex) neurotransmitters at the axon

Answer 18

vesicle docks
priming occurs
Ca2+ signals for an intake action potential
membranes fuse
firing

Question 19

how do toxins interfere with synaptic signalling and give some examples

Answer 19

cleave the trans snare complexes
so vesicles cannot dock

tetanus, botulinum

Question 20

what is endocytosis and the different types

Answer 20

intake of molecules from the extracellular space

pinocytosis
phagocytosis

Question 21

what is pinocytosis

Answer 21

non specific uptake
recycling of membrane
is receptor mediated

Question 22

what is phagocytosis

Answer 22

interact with receptors
cytoskeleton rearanges to make pseudopods
phagosome forms
phagolysosome forms

Question 23

what occurs to endocytosed vesicles (endosomes)

Answer 23

recycled by recycling endosomes

vesicles go to different parts of the cell membrane to spread the material (transytosis)

degradation cargo proteins send to late endosomes to mature into lysosomes
macromolecules are degraded to make new molecules