Intracellular Compartments and Protein Transport

Question 1

Eukaryotic cells have a general set of what?

Answer 1

Organelles

Question 2

Internal membranes create what within a cell

Answer 2

Compartments

Question 3

Most organelles are part of what system

Answer 3

The endomembrane system

Question 4

Are mitochondria and chloroplasts part of the endomembrane system?

Answer 4

No they are not

Question 5

Different compartments are home to different processes that need different what?

Answer 5

Proteins

Question 6

Where does all protein translation initiate

Answer 6

In the cytosol

Question 7

Proteins that are destined for an organelle will have what in the AA sequence

Answer 7

Sorting signal

Question 8

Signals maybe be altered, what happens when this takes place?

Answer 8

A protein enters a different organelle

Question 9

To enter an organelle, proteins must cross what?

Answer 9

A membrane

Question 10

Proteins destined for the nucleus use what

Answer 10

Nuclear pores

Question 11

Other organelles have what in their membranes

Answer 11

Protein translocators

Question 12

Some proteins move from one organelle to another by what?

Answer 12

Vesicles

Question 13

Nuclei have what type of membrane structure

Answer 13

Double membrane structure

Question 14

Signal sequences in polypeptides bind what in the cytoplasm following translation

Answer 14

Nuclear import receptors

Question 15

Nuclear import receptors guide proteins where?

Answer 15

Nuclear pores

Question 16

G-protein superfamily members bind to what

Answer 16

GTP or GDP

Question 17

When GTP is bound, is it active or inactive

Answer 17

Active!

Question 18

GAP

Answer 18

GTPase activation of G-protein, turning off the G-protein

Question 19

GEF

Answer 19

Exchange factor, swaps for GDP, activating the G-protein

Question 20

Receptores on a membrane of the other organelles recognize what in a polypeptide

Answer 20

A signal sequence

Question 21

The polypeptides are unfolded to pass through the membrane proteins by what?

Answer 21

By recognition of the sorting signal

Question 22

The signal is cleaved upon entrance and then what happens

Answer 22

Chaperone proteins refold the polypeptides

Question 23

All mRNA associate with what in the cytosol

Answer 23

Ribosomes

Question 24

If an ER signal sequence is synthesized, where does the ribosome go

Answer 24

The ribosome moves to the ER membrane

Question 25

The final polypeptide moves into the ER through what

Answer 25

A protein translocator

Question 26

Many proteins enter what as they are translated?

Answer 26

The ER

Question 27

Translation initiates where

Answer 27

The cytoplasm

Question 28

Translation of the sorting signal causes what

Answer 28

The polypeptide and ribosome to associate with the ER

Question 29

What does the protein do during protein transfer

Answer 29

The protein may stay in the ER or get exported to other sites within the cell

Question 30

Water soluble proteins pass where

Answer 30

To the ER lumen

Question 31

Transmembrane protein embedded where

Answer 31

In the ER membrane

Question 32

Is the ER the final destination for most proteins?

Answer 32

No

Question 33

The ER produces transport vesicles to transfer many proteins to the golgi for what

Answer 33

For final processing

Question 34

From the golgi, transport vesicles are distributed where?

Answer 34

To other parts of the cell

Question 35

ER is a major site of folding for complex proteins which require what

Answer 35

Chaperones to aid their final confromation

Question 36

Unfolded protein response can trigger what

Answer 36

Growth of the ER to improve folding if quality of folding declines

Question 37

What can be triggered is UPR persists

Answer 37

Apoptosis

Question 38

Vesicular transport relies on what

Answer 38

Membrane budding and membrane fusion

Question 39

Membrane fusion requires what

Answer 39

V-SNARES, T- SNARES, Rab, & Tethering proteins

Question 40

Specialized proteins in vesicle membranes determine what

Answer 40

the destination through binding to the correct structure

Question 41

Vesicles bud from the ER and travel where?

Answer 41

to the cis-Golgi apparatus (the side of the Golgi towards the ER)

Question 42

Golgi enzymes further modify the proteins by adding what?

Answer 42

CHOs or other chemical groups

Question 43

The materials pass through the Golgi until they reach what conformation

Answer 43

the trans-Golgi apparatus (the side away from the ER)

Question 44

The mature products are packaged into what?

Answer 44

vesicles and transported to their final destination

Question 45

Substances leaving by fusion to the plasma membrane =

Answer 45

exocytosis

Question 46

Clathrin-coated vesicles interact with dynamin to more readily pinch what

Answer 46

vesicular membrane from its parent

Question 47

Endocytosis

Answer 47

Allows cells to import large molecules using vesicles called endosomes

Question 48

Bring in water and dissolved substances =

Answer 48

pinocytosis

Question 49

Bring in food or other non-dissolved substances =

Answer 49

phagocytosis  produces a specialized endosome called a phagosome

Question 50

Phagosomes fuse with lysosomes and produce what

Answer 50

a harsh environment * Acidification * Oxidation * Digestive enzymes

Question 51

Even without fusion to lysosomes, association with H+ pumps can create what?

Answer 51

pH-dependent effects on vesicle contents * May still help destroy dangerous contents * Can also be exploited by viruses

Question 52

Cellular Digestion

Answer 52

Endocytic pathways allow cells to degrade large structures or shut off signalling

Question 53

Endocytic pathways lead to what

Answer 53

Dysfunctional organelles * Bacteria * Membrane proteins which need deactivation * Removal of attached ligands @ PM