Nucleus

Question 1

What does the nuclear pore complex regulate?

Answer 1

It regulates movement in and out of the nucleus.

It is selective

Question 2

What is the nuclear envelope also known as?

Answer 2

Nuclear membrane

Question 3

What is the inner and outer layer of the nuclear envelope?

Answer 3

lipid bilayer
inner membrane is a binding site for chromosomes
outer membrane is continuous w/ ER and studded w. ribosomes

Question 4

Describe the shape of the NPC?

How many nucleoporins are there?

Answer 4

Octagonal Symmetry

20 NPC proteins

Question 5

How many NPC are there per cell?

Answer 5

3k-4k NPC per cell

Question 6

How many macromolecules does the npc transport per second?

Answer 6

500 macromolecules

Question 7

There is bidirectional movement in the NPC

How large are proteins that cannot pass via passive diffusion?

Answer 7

60k Daltons

Question 8

What happens to the nuclear membrane during mitosis?

Answer 8

It breaks down during prophase

The NPC and nuclear lamina dissemble and the envelop fragments

Question 9

What can move in the nuclear pore?

Name 3 things

Answer 9

Building blocks for DNA+RNA synthesis

Molecules used to provide energy

Ribosomal proteins made in cytoplasm then go back into nucleus

Question 10

What can move out of the nuclear pore?

Name one thing

Answer 10

Ribosomal subunits synthesized by the nucleolus

Question 11

Why is the function of the NPC important?

Answer 11

Allows nucleus and cytoplasm to maintain distinct populations if proteins

Question 12

What size of molecules can move through the nuclear membrane?

Answer 12

Small molecules <5 Kda rapidly move freely in/out
Larger move more slowly
>60Kda can barely pass freely

Question 13

What is the Nuclear Location Signal?

Answer 13

Amino Acid sequence that tags a protein anywhere on its surface for entry into the nucleus

Question 14

What is the Nuclear Export Signal?

Answer 14

Amino Acid sequence that tags a proteins for exit from the nucleus

Question 15

The ER constitutes for how much of the cellular membrane in an animal cell?

Answer 15

50%

Question 16

Name 3 functions of the ER

Answer 16

ER has key role in protein and cell synthesises
Contains Ca2+ stored which is important to signalling process
sit of synthesise of transmembrane proteins and lipids for cell organisation

Question 17

Where do most proteins destined for secretion or the ER lumen golgi or lysosome are initially delivered where?

Answer 17

Initially delivered to the ER

Question 18

What are the 2 types of endoplasmic reticuculm?

Answer 18

Smooth and Rough

Question 19

What is transitional ER?

Answer 19

Areas of smooth ER where proteins and lipid move to the Golgi.

Question 20

Describe co-translational protein import into the ER

Answer 20

Import of proteins into ER before its complete synthesise of the polypeptide chain

Question 21

Describe the signal hypothesis

Answer 21

Translocator is closed until ribosome binds
N-terminal signal peptide intimates passage of protein through the translocator
Signal peptide cleaved by signal peptidase
Mature protein located in the ER Lumen
Ribosome released and translocator close so permeability is retained

Question 22

When synthesised where is the protein imported for?

Answer 22

Imported from the cytosol

Question 23

What is a polysome ?

Answer 23

a cluster of ribosomes held together by a strand of messenger RNA which each is translating.

Question 24

What is protein glycosylation ?

Answer 24

Attaching carbohydrates to proteins
N-linked glycosylation to asparagine residues
Precursors oligosaccharide transferred from a dolichol lipid anchor catalysed by a transmembrane oligosaccharyl transferase enzyme
Trimming of the oligosaccharide occurs in the golgi

Question 25

Where does protein glycosylation occur?

Answer 25

In the ER

Question 26

Who discovered the Golgi Apparatus and when?

Answer 26

Camillo Golgi in 1898

Question 27

What are the 2 main functions of the Golgi?

Answer 27

Major site of carbohydrate synthesis

Part of secretory pathway to sort and dispatch proteins made in ER

Question 28

Describe how vesicles get from the ER to the Cis Golgi

Answer 28

COPII vesicles shed the COPII coat and fuse to form the vesicular tubular cluster
This fuses with the cis-Golgi
KDEL receptor retrieves proteins back to the ER

Question 29

Describe the movement of the Vesicles from the ER to the Golgi

Answer 29

Vesicles bud off the ER at specialised exit sites w. COPII coat,
Coat allows fusing to Golgi and plays a role in recruiting proteins with exit/transport signal
Incorrectly folded proteins are retained in the ER

Question 30

What were the two proposed routes for proteins through the Golgi?

Answer 30

Cisternal Maturation and vesicle transport