lecture 9 ( Intracellular Compartments and Protein Transport)

Question 1

which types of protein needs to enter through the ER first?

Answer 1

1) golgi apparatus protein
2) endosomes
3) lysosomes
4) to the surface of the cell
5) outside the cell

Question 2

The 2 types of protein transferred to the ER:

Answer 2

• water soluble protein (crosses the membrane completely)
• prospective transmembrane protein (embedded)

Question 3

what is the ER signal sequence?

Answer 3

its a segment of 8 or more hydrophobic amino acid

Question 4

what affect does the SRP binding to ribosome carrying the protein have on protein synthesis?

Answer 4

it slows the protein synthesis until the SRP receptor engages

Question 5

what is the two types of polyribosomes?

Answer 5

• polyribosomes free in cytosol (free ribosomes)
• polyribosomes bound to ER (membrane bound ribosome)

Question 6

what causes the transmembrane protein to be embedded in the ER membrane?

Answer 6

the hydrophobic stop signal sequence remins uncleaved therefore the protein is embedded.

Question 7

what removes the start transfer sequnce after protein is synthesized in the ER?

Answer 7

signal peptidase

Question 8

what is the 2 functions for the ER signal sequnce ?

Answer 8

1) directing protein to the ER
2) opens the gate of the channel of the translocator

Question 9

There are two types of Transmembrane Protein:

Answer 9

1) Single Pass Transmembrane Protein
2) Multi Pass Transmembrane Protein

Question 10

What is the function of the SRP receptor?

Answer 10

releases the SRP and passes the protein to the Translocator.

Question 11

what causes the transmembrane protein to be thredded across the ER membrane?

Answer 11

the multiple start and stop hydrophobic signles allows the continuation of protein synthesis without drafting away from the lipid bilayer and without removing the start signle sequnce.

Question 12

True or False: the free polyribosomes is the ribosomes on the Rough Endoplasmic Reticulum.

Answer 12

False, the membrane bound polyribosomes

Question 13

The movement of secretory pathway:

Answer 13

ER -> Golgi appartus -> Cell surface

Question 14

The movement of Endocytic Pathway:

Answer 14

molecules from the plasma membrane -> endosomes -> lysosmes

Question 15

what is the endocytic pathway responsible for?

Answer 15

responsible for the degradation of extracellular molecules

Question 15

what is the endocytic pathway responsible for?

Answer 15

responsible for the degradation of extracellular molecules

Question 16

What are Coated Vesicles?

Answer 16

vesicles that bud from membrans of distinctive protein surface

Question 17

True or False:The best way to study vesicles is by clatherin vesicles

Answer 17

True

Question 18

Clatherin Coated Vesicles

Answer 18

vesicles that transport proteins from the golgi to the outside and from the plasma membrane to the inside

Question 19

Dyamin is:

Answer 19

an intercellular protein shaped as a ring around the neck of the coated pit and pinches the vesicle away from the orgin membrane

Question 20

what is the protein coat for golgi clathrin vesicles?

Answer 20

clathrin + adaptin 1

Question 21

what is the protein coat for plasma membrane clathrin vesicles?

Answer 21

clathrin + adaptin 2

Question 22

how does vesicles select cargo?

Answer 22

through the adaptin by trapping the receptor carrying that signal

Question 23

How does the targeted membrane identifies vesicles?

Answer 23

by tethering protein which recongnizes Rab protein (on the vesicle) on the surface of the memebrane

Question 24

True or False: The identification process depends on a diverse family of monomeric
GTPases called Rab proteins.

Answer 24

True

Question 25

True or False: Each organelle and each type of transport vesicle carries the same combination of Rab proteins

Answer 25

False, different combination which acts as a marker for each membrane type.

Question 26

What are SNARE’s

Answer 26

it’s an additional recognition protein (transmembrane protein). v-SNARE is the protein on the vesicle which firmly attaches to the t-SNARE which is the protein on the targeted membrane to firmly adjust the vesicle for fusion.

Question 27

What is the type of COP protein originated from the 1) ER 2) Golgi cisterna 3) Golgi apparatus?

Answer 27

1) COP 2
2) COP 1
3) COP 1