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Cell Bio And Histology > Intracellular Trafficking > Flashcards

Intracellular Trafficking Flashcards

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Biology 101 flashcards
0
Q

Proteins being translated on membrane bound ribosomes and then translocated into the ER lumen describes

A

Co-translational translocation

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1
Q

Synthesis of all proteins begins?..

A

On free ribosomes

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2
Q

Proteins being translated on free ribosomes and then trans located into the ER lumen describes?

A

Post-translational translocation (more commonly in yeast)

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3
Q

Define intracellular trafficking?

A

Movement of material, mainly proteins, from compartment to compartment within the cell and to and from the external environment via membrane bound vesicles.

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4
Q

Non selective endocytosis that forms vesicles with extra cellular fluid and its contents.

A

Fluid phase endocytosis

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5
Q

Ligand binds with a receptor along the cell membrane

A

Receptor mediated endocytosis.

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6
Q

Clathrin has a role in both endo- and exo-cytosis. What is it?

A

Coats pits involved in selective endocytosis

Coats secretory vesicles of regulated pathway for exocytosis

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7
Q

The process of removing the Clathrin coat immediately after the release of the new vesicle into the cytoplasm requires what?

A

ATP and Hsp70 (heat shock protein)

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8
Q

This type of coatamer coat vesicles transported from ER to CGN

A

Cop II

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9
Q

Cop I coatamers coat vesicles transported between?…

A

Golgi stacks

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10
Q

Vesicle fusion is a two step process. What are the steps?

A

1) recognition of the appropriate membrane
snare-v and snare-t

2) fusion of the vesicle and target membrane.
* NSF
* SNAPS

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11
Q

List the 8 sequence of events in a vesicle docking

Biggest crock of shit thus far

A

1) removal of the vesicle coat
2) binding of synapsins and spectrin
3) snare v binds to snare v
4) snap binds to snare
5) NSF bind to snap
6) NSF/snap complex disassembles snare for reuse
7) release of NSF and snap from snare
8) initiation of calcium dependent membrane fusion
* requires fusigen

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12
Q

Proteins that are destined for export from the cell or are destined to be stored in lysosomes utilize the following pathway?…

A

Free ribosomes> RER> Golgi> secretory vesicles or lysosomes.

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13
Q

What’s the first part of the protein to be synthesized?

A

The signal sequences consisting of 20 amino acids and includes a stretch of hydrophobic residues

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14
Q

What’s the role of the signal sequence?

A

To direct the ribosomes to attach to the ER membranes.

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15
Q

What attaches to the signal sequence to prevent any further elongation?

A

A signal recognition particle (SRP) made up of six proteins and a 7s segment of RNA.

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16
Q

When does protein elongation resume?

A

Once the SRP docks with its like receptor, the signal sequence is inserted in the translocon membrane channel where it is released following cleavage of the signal sequence by a signal peptidase.

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17
Q

What is a translocon?

A

three transmembrane protein complex.

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18
Q

What does HSP (70) function in? And what is another name they go by?

A

HSP (70) keeps the polypeptide chain unfolded so the signal can enter the channel.

Protects the cell from high temperature

Directs folding of proteins

Chaperone protein

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19
Q

Clathrin consists of what kind of subunits to form geometric shapes?

A

Triskelion

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20
Q

BiP aids in what? And they are a type of what kind of protien?

A

The folding and assembly of multisubunit proteins.

Heat shock protein

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21
Q

The sugar chain, which is linked by (?), to the asparagine residue was initially attached to the luminal face of the ER by (?)

A

N-linked glycosylation

A lipid carrier dolichol phosphate

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22
Q

The cytoplasm of the ER consists of two compartments?…

A

Luminal (endoplasmic) compartment

Cytoplasmic (cytosolic) compartment

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23
Q

The ER is divided into three compartments. What are they and their function?

A

Smooth ER- detoxifies toxins and for lipid synthesis. Without ribosomes on the cytoplasmic face

Rough ER- synthesis of proteins. Has ribosomes on the cytoplasmic face

Transitional ER- where vesicles exit to the Golgi apparatus

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24
Q

This leaflet faces the cytoplasm of the cell

A

Protoplasmic leaflet

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25
Q

This leaflet faces the lumen of the ER

A

Exocytoplasmic leaflet

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26
Q

Proteins targeted for the nucleus, mitochondria, or perioxisomes are synthesized on?…

A

Free ribosomes and then released into the cytosol

27
Q

Proteins for secretion or targeted to the Golgi, lysomes, ER, or PM are synthesized on?…

A

Ribosomes bound for the RER

28
Q

Proteins targeted to lysosomes, secretion, or Golgi apparatus are transported in vesicles that bud off?…

A

The transitional ER

29
Q

Proteins that are destined to be attached to the PM have what attached to their carboxyl end? Where will they face?

A

GPI (a really long word) anchors. Luminal leaflet on the outside of the cell

30
Q

What directs correctly folded proteins to the transitional ER?

A

A folding sensor

31
Q

A folding sensor will add a glucose residue to the misfolded protein and send it where for another attempt at folding?

A

Calreticulin (a chaperone )

32
Q

Severely misfolded proteins at sent back through the translocon and are degraded in proteosome a located?…

A

In the cytoplasm

33
Q

Where are phospholipids synthesized and what does it mean for any new phospholipids?

A

On the cytosolic side of the ER from glycerol. And can only be added to the cytosolic leaflet.

34
Q

Phospholipids that are TO BE located on the luminal side of the ER are transferred via?…

A

Flippase proteins

35
Q

What are the two faces of the Golgi?

A

Cis-entry

Trans-exit

36
Q

What are the four functions of the Golgi apparatus?

A
  • modifications of carbohydrates (glycosylation)
  • sorting of cargo to cell destination weddings
  • synthesis of sphingomyelin and glycosphingolipids
  • o linked glycosylation (addition of carbs to Ser and Thr)
37
Q

What is anterograde trafficking?

A

Vesicles carrying cargo in the cisternae from the Cis to the trans face.

38
Q

What is retrograde trafficking?

A

Cis face back to the Rough endoplasmic reticulum

39
Q

What are the two types of secretory pathways?

A

Facultative and constitutive

40
Q

Describe facultative secretion?

A

Cargo stored in vesicles and only released in t cytoplasm in response to extracellular signals.

Ex: neurotransmitter or hormone

41
Q

Describe constitutive secretion?

A

Cargo is secreted continuously without the need of an extra cellular signal.

  • Includes newly synthesized lipids
  • Proteins to the PM
  • Proteins of the EC matrix
42
Q

What is the targeting signal for lysosomal pathways?

A

Mannose-6-phosphate

43
Q

Mannose 6 phosphate residues become what?

A

Acid hydrolases

44
Q

Residues are …. To protect them from being removed by enzymes in the CGN

A

Phosphorylated

45
Q

TGN jam packs all the phosphorylated M6Pases into transport vesicles and surrounded with what as it exits the Golgi?

A

Clathrin

46
Q

Clathrin is immediately shed after it exits the Golgi in order to bind to other…

A

Somal bodies (endosomes, phagosomes, etc…) already in the cytosol.

47
Q

Identify the five types of lysosomes

A
  • Primary-just buds off the TGN.
  • Secondary- primary fuses with a fagosome and filled with protons (hydrogens) to create a pH of 5
  • Residual body-reminents of a secondary lysosome with undigested material
  • Early-endocytic vesicle with internal pH mMof 7.35
  • Late-endocytic vesicle fused with a lysosome with pH of 5
48
Q

Residual bodies may be eliminated by?…

A

Exocytosis

49
Q

Proteins destined for the nucleus contain what type of signal? And describe the signal

A

Nuclear localization signal.

Consists of 4-8 amino acids with positive charged residues. Components of the nuclear pore complex recognize the signal and position it for import into the nucleus.

50
Q

T/F NLS is removed after import.

A

False. It can be used to recycle the protein

51
Q

What marks proteins for transport into the mitochondria?

A

N-terminal signal sequence.

Positively charged amino acids with proceeding polar and non polar residues.

52
Q

A mitochondrial signal sequence may direct proteins to specific compartments within the organelle. What are the compartments?

A

Outer membrane
Inter membrane space
Inner membrane
Matrix

53
Q

Prior to import into the mitochondria, proteins are maintained in a partially unfolded state by this chaperone protein?

A

HSP 70

54
Q

Where does the signal sequence bind to on the mitochondria?

A

A receptor on the outer membrane

55
Q

Proteins in the mitochondria are transferred across both outer and inner membranes into the matrix via?

A

TOM complex with the usage of ATP.

56
Q

What is another chaperone protein that helps assist the final folding of a protein once it reaches it’s destination in the mitochondria?

A

HSP 60

57
Q

Let’s get in the mindset of micro tubular transport to the axon. Going from the cell body to the axon terminus involves?

A

Anterograde and involves kinesins

58
Q

Let’s go back from the axon terminus to the cell body? What’s involved in that?

A

Retrograde and involves cytoplasmic dynein

59
Q

There are five motor proteins. What are they? We will discuss each of them after. So just name them for now.

A

Kinesins, cytoplasmic dynein, myosin (I, II, V)

60
Q

Myosin II is a conventional motor protein. Tell me about it.

A

Found in both muscle and non muscle cells

ATPase head

Paired molecules liked by tails

Binds to actin

Moves towards the plus end of actin.

61
Q

Myosin I is an unconventional motor protein. Tell me about it.

A

Found in all cell types

Single ATPase heads binds to F actin

Tail binds to cell membranes of vesicles

Moves toward plus end of Actin

62
Q

Myosin V is an unconventional MP. Tell me more.

A

Two heads and double tail

Found in all cell types

Head binds to F actin

Tail binds to cell membranes of vesicles

Moves towards the plus end of actin

63
Q

Found in all cell types, two heads bind to microtubules, tail binds to cell membrane of vesicles, moves towards “PLUS +” end of microtubules. What am I?

A

Kinesin

64
Q

Moves towards the MINUS - end of microtubules?

A

Cytoplasmic dynein

Cell Bio And Histology (17 decks)

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