Intracellular Compartments and Protein Sorting 1

Question 1

Describe the plasma membrane

Answer 1

outer boundary of cells, bilayer
protective barrier
has transporters
signaling

Question 2

Describe the nucleus

Answer 2

contains the genome

principal site for DNA and RNA synthesis

Question 3

Describe the cytoplasm

Answer 3

consists of cytosol and cytoplasmic organelles

intermediary metabolism

Question 4

Describe the endoplasmic reticulum

Answer 4

with ribosomes attached (rough ER), no ribosomes (smooth ER)

protein synthesis, lipid synthesis, protein folding, quality control, storage of calcium, signaling

Question 5

Describe the golgi apparatus

Answer 5

stacks of disc like compartments

post translational changes on protein and lipids, trafficking

Question 6

Describe the mitochondria

Answer 6

outer and inner membrane and matrix

energy metabolism, signaling, cell differentiation and cell death

Question 7

Describe the lysosomes

Answer 7

contain digestive enzymes that degrade organelles and biomolecules

Question 8

Describe the peroxisomes

Answer 8

small vesicular compartments that contain enzymes used in oxidation reactions

Question 9

What are the 3 topological categories the cell is divided into?

Answer 9

nucleus and cytosol
organelles in secretory and endocytic pathways
mitochondria

Question 10

Membrane _________ and ________ allows the lumen of these compartments to _______ with each other and with the ________

Answer 10

budding; fusion; communicate; cell exterior

Question 11

What is gated transport?

Answer 11

Between nucleus and cytosol through nuclear pore complexes ( active transport and free diffusion)

Question 12

What is transmembrane transport?

Answer 12

membrane protein translocators directly transport specific proteins from cytosol across an organelle membrane

Question 13

What is vesicular transport?

Answer 13

membrane enclosed transport intermediates move proteins between various compartment via vesicles

Question 14

What guides protein transfer/transport to various compartments?

Answer 14

sorting signals

Question 15

What is a sorting signal?

Answer 15

stretch of amino acids, typically 15-60 residues long

Question 16

Where is a sorting signal localized?

Answer 16

on N or C terminus or within protein sequence

Question 17

Multiple scattered sequences in protein may form ______

Answer 17

signal patch

Question 18

What removes the signal after protein reaches final destination?

Answer 18

signal peptidase

Question 19

Signal sequence are both necessary and sufficient for what?

Answer 19

protein targeting

Question 20

_____ properties of sequence are more important than actual sequence

Answer 20

physical

Question 21

What are signal sequences recognized by?

Answer 21

complementary receptors

Question 22

What does the signal sequence that functions to import into the nucleus contain?

Answer 22

lysines and arginines

Question 23

What does the signal sequence that functions to import into mitochondria contain?

Answer 23

positively charged and hydrophobic amino acids

Question 24

What does the signal sequence that functions to import into ER contain?

Answer 24

hydrophobic amino acids

Question 25

What does the signal sequence that functions to return to the ER contain?

Answer 25

KDEL

Question 26

Describe nuclear transport

Answer 26

gated
bidirectional
selective

Question 27

Proteins needed in the nucleus are imported from where?

Answer 27

cytoplasm

Question 28

What are nuclear pore complexes composed of?

Answer 28

30 different proteins or nucleoporins

Question 29

How are nuclear pore complexes arranged?

Answer 29

in octagonal symmetry with one or more aqueous pores

Question 30

Do nuclear pore complexes transport molecules in one or both directions?

Answer 30

both

Question 31

In nuclear pore complexes, Transport facilitated by binding of particles to ______ extending from NPC

Answer 31

fibrils

Question 32

What are nuclear localization signals?

Answer 32

sorting signals that direct molecules to nucleus

Question 33

What are nuclear localization signals rich in?

Answer 33

positively charged amino acids, lysine and arginine

Question 34

Where are nuclear localization signals located?

Answer 34

different sites on protein

form loops or patches on surface

Question 35

Nuclear localization signals are recognized by ______

Answer 35

nuclear import receptors

Question 36

Nuclear import receptors are _____________ proteins that bind to _______ on protein and to ______ proteins present on fibril that extend into cytoplasm

Answer 36

soluble cytosolic; nuclear localization signal, nuclear pore complex

Question 37

What kinda of repeats do NPC proteins have? What do they serve as?

Answer 37

have phenylalanine glycine (FG) repeates

serve as binding sites for import receptors

Question 38

Nuclear export relies on a ________ on molecules that need to go out of nucleus.

Answer 38

nuclear export signals

Question 39

Nuclear export signals need complementary what?

Answer 39

nuclear export receptors

Question 40

Proteins that contain NLS and NES shuttle back and forth between what?

Answer 40

nucleus and cytosol

Question 41

Steady state localization depends upon _________ of transport

Answer 41

relative rate

Question 42

If rate of import is greater than export, it is considered ______

Answer 42

nuclear

Question 43

Changing rate of import/export can do what?

Answer 43

change location of protein