Golgi

Question 1

transport of protein (general stops)

Answer 1

ER—> ER-golgi intermediate compartment (ERGIC) –> golgi apparatus

Question 2

exocytosis

Answer 2

membrane insertion

or lumenal aspects of lysosomes

Question 3

Vesicles

Answer 3

transports proteins to and from ER and golgi (and can go to other parts of the cell)

Question 4

vesicle passing is mitigated by …

Answer 4

signals on the protein

Question 5

Golgi Structure

Answer 5

• not contiguous
• stacks of sacks (cisternae)
• has polarity on struc and function
  -Cis face recieves from ERGIC

Question 6

medial cisternae

Answer 6

middle of the stack

Question 7

cisternae are usually…

Answer 7

swollen at the margins, where vesicles arise and fuse

Question 8

Trans face faces …

Answer 8

away from the RER towards cell surface

trans-golgi network recieves from the trans face

Question 9

the golgi complex

Answer 9

assembly line for modifying and packaging lumenal and transmembrane proteins

Question 10

protein modifications

Answer 10

medial and trans compartments
–> removing/adding/ modifying carb and lipid components
—> covalently coupling protein and lipid components attach. to mem/secretory proteins
–> some proteins polymerize in the golgi

Question 11

Lipid metabolism

Answer 11

med/trans compart.

–>convert ceramide (a base sphingolipid) into sphingomyelin or glycolipid

Question 12

sorting proteins: trans golgi network

Answer 12

for delivery to their final cellular destination

Question 13

Mod of Glycoproteins

Answer 13

• poly sacc added in the ER
• golgi mod to result in variety of glycoproteins serving spec functions (Mod depend on pro structure and enzymes available)

Question 14

passing through golgi stacks

Answer 14

2 mech:

1. cisternal Maturation model
2. stable cisternae model

Question 15

cisternal maturation model-

Answer 15

the entire stacks will move from cis to trans, maturing their proteins as they move

Question 16

stable cisternae model

Answer 16

the stacks stay put, but send proteins from one stack to the next as the proteins mature

Question 17

Vesicles formation and function

Answer 17

formed by membranes within cells

Move cargo and mem-bound proteins bt compartments w/in the cell
“pinching” the mem off each organelle to form a vesicle

Question 18

Vesicular transport

Answer 18

selective!

coats assemble in the cytosol causing vesicles to bud off and separate
coats removed before delivery. vesicles fuse with target mem and empty their cargo, and insert their mem along with any mem proteins into target mem

Question 19

steps of vesicular transport (coats)

Answer 19

1. COP II-carry proteins from the ER–> ERGIC –>Golgi apparatus.
2. COP I-coated vesicles bud from the ERGIC or Golgi and carry their cargo back, returning proteins to earlier compartments.

Question 20

Clathrin and dynamin

Answer 20

triskeleton shape (trimer) base- induces curvature on plas mem when it polymerizes

when vesicle is sphericle dynamin comes to “pinch” it off to release ves into cytosol

Question 21

forming GTP-binding proteins like ARF

Answer 21

Guanine nucleotide Exchange Factors (GEFs) activate ARF by exchanging GDP for GTP (ARF + GTP = active)

Question 22

active GTP-bound ARF recruits…

Answer 22

Adaptor proteins that mediate vesicle assembly by interacting with cargo proteins and with coat proteins
- Adaptor proteins (AP) are what attaches the different coat proteins
- Different APs, different coats (this example is specific for clathrin.).

Question 23

steps of budding and release

Answer 23

Activated and regulated by ARF and ARF-GEF
in GDP form- ARF is lazy
GTP form- causes vesicle formation
—> recruits clathrin
Dynamin pinches the stalk and clathrin unbinds

Question 24

vesicle fusion step 1

Answer 24

1. The vesicle must recognize the correct target membrane—> Rab proteins—> SNARES

Question 25

Ves Fusion step 2

Answer 25

2. Vesicle and target membrane must fuse, delivering the contents to the target organelle—> SNARES

• V (vesicular) and T (target) SNAREs are important for the correct targeting and fusion of vesicles

Question 26

Vesicle docking

Answer 26

1. loose V-snare, t-snare, Rab, and tether interaction
2. Rab activation of snares and tight V/T snare interaction

Question 27

KDEL

Answer 27

If a protein contains the amino acid sequence LYS-ASP-GLU-LEU (KDEL), that indicates the protein is an ER-lumenal protein and needs to be returned back to the ER.

Question 28

Constitutive vs regulated pathways

Answer 28

C: carries out routine deliveries of pro to plas mem, secretes “normal materials”, its the default and uses sig sequence

R: vesicles that bud off and travels to region just under plas mem, specific and speacialized by ca2+ changes. mechanism of NT release

Question 29

Endosomes

Answer 29

1. early: fuse w endocytic vesicles–> separates into recycling and late
2. Rec: constituents that the cell wouldnt want to destroy are sep out
3. late: pH starts to drop bc ves containing proton pump start to fuse —> will become lysosomes

Question 30

proteasome

Answer 30

barrel like assem of pro in cytoplasm “the cells garbage can”

Question 31

autophagy

Answer 31

done by lysosomes, cell turnover, vesicle fuses and then digested. Process can be repeated

important during apoptosis!