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C Bio > Golgi Apparatus & Vesicular Traffic (14) > Flashcards

Golgi Apparatus & Vesicular Traffic (14) Flashcards

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Biology 101 flashcards
1
Q

location of golgi

A

b/w the ER & cell surface

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2
Q

structure of golgi

A

membrane-bound stacks called cisternae

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3
Q

function of golgi

A

modify & sort PROs for export or for other organelles, tag PROs ensuring they go to the correct location

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4
Q

how are the stacks of the Golgi named?

A

their proximity to the ER

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5
Q

trans-Golgi network

A

vesicles that bud off of Golgi & move to diff places in the cell

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6
Q

how do the cisternae layers differ among each other?

A

each department has unique enzymes

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7
Q

how can the Golgi be studied?

A

electron microscope

staining the layers based on their diffs in enzyme composition

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8
Q

Cis region

A

sugars & PROs are phosphorylated

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9
Q

medial region

A

have enzymes that remove carbs that were added in the ER & then add new carbs

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10
Q

trans region

A

area where lysosomes are sorted

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11
Q

what enzyme is the trans region rich of?

A

acid phosphatase`

enzyme found in lysosomes

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12
Q

N linked glycoPROs

A

sugars attached at the N of the asparagine

Begins in ER & continues in Golgi 

Glycosyltransferases facilitate the attachments
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13
Q

Glycosyltransferase

A

add sugars to the N of aspargine in N linked glycoPROs

found in the Golgi

act in a rigidly determine sequence

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14
Q

O-linked glycoPROs

A

sugars attached to the O of serine of threonine

occurs only in the Golgi

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15
Q

what is the diff b/w O-linked & N-linked glycoPROs?

A

attachment of the sugar: N –> N of asparagine & O –> O of serine or threonine

Location of attachment: N –> Golgi & ER & O –> Golgi only

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16
Q

how does glycosylation of PROs effect their solubility?

A

more hydrophilic & therefore, increases solubility

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17
Q

Glycosylating PROs allows them to bind where?

A

extracellular matrix

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18
Q

what is a way for PROs to have more specific interactions?

A

through glycoPROs

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19
Q

why glycosylate PROs?

A

Increases their solubility by making them hydrophilic

Enables binding to the extracellular matrix

Reduces susceptibility to proteases, carbs act as a physical barrier protecting the PRO core
Protects cell surface

Structural complexity to the PRO
New function
Provides more specific interactions with other PROs

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20
Q

where do we see an abundance of glycosylated PROs?

A

cell’s surface where cell-to-cell interactions occur

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21
Q

what creates diversity of AAs?

A

phosphorylation & glycosylation

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22
Q

what contents move through the Golgi?

A

membranes including PROs, phosphoglycerides & other membrane lipids

vesicles including PROs being processed & enzymes doing the processing

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23
Q

transient/anterograde movement

A

forward

cis to trans

24
Q

retrograde movement

A

trans to cis

reverse

25
Q

cisternal maturation model. When does this occur? & how?

A

each cisternae is physical moved up the stack & changes composition

Enzymes seem localized to departments but vesicles can come & go 
Maturation process 
New vesicles form causing upwards movements 
Done when macromolecules require transport (can’t fit in vesicles)
26
Q

vesicular transport model

A

materials in the interior & in the membrane are brought up to next cisternae by vesicle transport

vesicles bud off cis & then fuse with medial etc.

27
Q

what evidence is provided for the vesicular transport model?

A

vesicles were found to move both forward & backwards so they could maintain enzymes diffs

28
Q

what evidence is provided for the cisternal maturation model?

A

there are some materials that are never seen in vesicles

including large molecules

29
Q

how do vesicles travel?

A

along microtubules, anchored by PROs including dynactin

30
Q

how do vesicles move?

A

travel along microtubules

dyenin can grab dynactin & pull the vesicle with it

Kinesin use other adaptor PROs recognizing PROs in the membrane

31
Q

when does the Golgi break up?

A

onset of mitosis during nuclear membrane degradation (prophase)

32
Q

when does the Golgi reappear in mitosis? & How?

A

telophase

Still UK but, growing microtubules may collect & algin small vesicles which later fuse together creating cisternae

33
Q

what is the role of coat PROs in vesicle formation?

A

mechanical force

34
Q

what is the role of integral PROs in vesicle formation?

A

selection of cargo

35
Q

what are the PROs found in a vesicle?

A

integral PROs binding cargo & other PROs to connect with the coat

36
Q

what are the 3 functions of the vesicles integral & peripheral PROs?

A

vesicle formation/budding

selection of vesicle contents by receptor sys

recognition & fusing target membrane

37
Q

COP II coated vesicles

A

forward movement from ER & b/w cisternae
o Anterograde movement
o Cis – medial – trans – OT

38
Q

COP I coated vesicles

A

retrograde movement from TGN to Golgi to RER

Trans – medial – cis … maybe back to ER

39
Q

clathrin-coated vesicles

A

TGN to lysosomes & endocytosis

Assoc with movement of vesicles from trans Golgi to other places

40
Q

bulk flow

A

non-specific contents are captured during vesicle formation

ex: water

41
Q

what types of contents are found in vesicles?

A

bulk flow

specific materials

42
Q

vesicle formation process

A

Receptor PRO with specificity to specific cargo

Will recruit PROs to help build coat

Coat will build vesicle

Vesicle will bud off

Vesicle will move to Golgi via motor PROs

43
Q

what are the requirements of vesicular transport?

A

selection of contents (receptor-mediated)

production of vesicles (PRO coat)

movement of vesicle (tethering/docking & membrane fusion)

44
Q

how do vesicle select their cargo?

A 
Receptors select & carry contents 
	High specificity & affinity for cargo & its target molecule 
	Integral PROs (ligand with cargo)

The target molecule is at low concentrations in the mixture, the receptor picks it out

For every cargo molecule there is a receptor holding it in place (1:1)
45
Q

How do vesicles bud off?

A

Coat PROs assemble at the membrane forcing the bilayer to bend

Coat PROs help gather the receptors that will carry the cargo

Shortly after the vesicle pinches off, the coat falls off & the vesicle is ready to travel to its destination

46
Q

steps in COP II coated vesicles

A
  1. Receptors bind selected PROs (cargo) within the lumen of the RER & assembles 2 PROs: coat PRO & GTPase Sar1
    PROs destined for secretion
    ER resident PROs such as BiP are left behind
  2. Sar1, a GTP binding PRO, if active promotes assembly of the coat
  3. Coat PROs bind to cytosol side of specific receptor in RER membrane, vesicle form determined by steric hindrance of coat PROs
  4. Coated bud forms & leaves the RER
    Taking along receptor/cargo complexes
    Also some membrane PROs (ex: Golgi glycosyltransferases)
    Also membrane PROs involved in docking/fusion: destination tags Rab & SNARES (not shown)
  5. Sar1 hydrolyzes the GTP GDP becoming inactive
  6. Disassembly of the coat (Sar1)
    Things in the lumen of the vesicle & in the membrane stay there
    Membrane-bound PRO but not integral
    Leaves the membrane
    Has a branch that pokes outside the membrane, GTP hydrolyzes occurs & causes it to change shape
  7. The vesicle is now able to fuse with the cis Golgi (vesicles are no longer coated)
47
Q

What activates Sar1?

A

attachment to GTP

48
Q

what inactivates Sar1?

A

GTP –> GDP

49
Q

what does a budded vesicle contain in COP II vesicles?

A

Taking along receptor/cargo complexes

Also some membrane PROs (ex: Golgi glycosyltransferases)

Also membrane PROs involved in docking/fusion: destination tags Rab & SNARES (not shown)

50
Q

what causes the coat PRO to fall off in COP II vesicles?

A

GTP –> GDP causing a change in shape

51
Q

What components required for the formation of COP II vesicles?

A

Receptors to bind cargo

Coat PRO

GTPase Sar1 promoting the assembly & disassembly of the coat PRO

Destination tags for docking/fusion (Rab & SNARES)

52
Q

what is required for a coat PRO to recognize a receptor?

A

ligand bound to a receptor

53
Q

What determines which PROs enter COP I vesicles?

A

PROs contain retrieval signals which are recognized by the receptor in the COP I membranes

54
Q

what signal is recognized by COP I receptors on soluble PROs?

A

KDEL

55
Q

what signal is recognized by COP I receptors on membrane PROs?

A

KKXX

56
Q

How does COP I look for KDEL receptors?

A

looks for KKXX sequence

C Bio (30 decks)

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