Endoplasmic reticulum Flashcards

1
Q

Important for intracellular —-storage

A

Ca+

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2
Q

RER makes most__ destined for secretion

A

protein

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3
Q

___embedded in the ER gives the rough appearance

A

ribosomes

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4
Q

Rough Er is the site of protein—- and —— also lipid —-

A

production and modification
lipid synthesis

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5
Q

Smooth ER is involved in lipid——, production of ——-and detoxification of —-

A

metabolism production of lipoprotein particles and detoxification of lipid soluble drugs

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6
Q

Transition ER are areas of—

A

smooth ER which form transport vesicles fro delivery to the Golgi

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7
Q

Smooth ER is important for intracellular —storage

A

Ca2+

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8
Q

Smooth microsomes have —-density and stop sedimenting and float at low sucrose concentration

A

low

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9
Q

Rough microsomes have a —-density and stop sedimenting and float at high sucrose concentration

A

high

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10
Q

ER reseals upon homogenization to form ——

A

microsomes

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11
Q

Proteins are either imported ——-or——-

A

co-translationally or post-translationally

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12
Q

Proteins are built from —- to —- term

A

N to C

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13
Q

The endomembrane system is composed of

A

the ER, Golgi, endosomes and lysosomes

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14
Q

RER appears in the ——micrographs b/c?

A

EM b/c of the ribosomes

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15
Q

RER is important for

A

protein folding and processing

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16
Q

What are the three ways proteins get translated?

A

translated completed
unfolded and then transported inot the ER lumen
co-translationally translocated

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17
Q

The smooth ER is important for?

A

storing calcium and detoxifying drugs

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18
Q

Both RER and SER are important for?

A

lipid biosynthesis

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19
Q

Proteins can enter the ER by which two ways?

A

post-translationally or co-translationally translocated

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20
Q

Co-translational translocation is dependent on?

A

an N-terminal signal sequence
the signal recognition patricle(SRP)
the SRP receptor and the translocon

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21
Q

What do stop transfer sequences allow for?

A

transmembrane domains to insert in cell membranes

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22
Q

What do start transfer sequences allow?

A

Non-N-terminal portions of the protein to iniate translocation

23
Q

Combination of start and stop sequences allow?

A

production of multi pass transmembrane proteins as well as transmembrane proteins with C rather then N terminus to the ER lumenal side

24
Q

What is N-linked glycosylation?

A

During translocation a block of 14 carbohydrates may be covalenty attached to the nitrogen on a asparagin residue within the recognition sequence Asn-X-Ser/Thr

Most proteins made at the RER are N-glycosylation in a co-translational manner by Oligosaccharyltransferase( a transmembrane protein complex of the RER)

25
Q

The N-linked carbohydrates are only added in the —-and modified in the —-

A

ER
Er and Golgi

26
Q

p450 enzymes are associated with

A

SER membranes

27
Q

p450 can?

A

oxidize drugs, this increases their solubility and may introduce OH groups which are sites for conjugation

28
Q

What is conjugation?

A

is the process by which fairly large soluble molecules are covalently attached to OH groups which allows drugs to be removed by kidneys or intestines

29
Q

What is the Golgi important for?

A

protein modification and sorting

30
Q

The golgi is the site for?

A

O-linked glycosylation, which makes up about 10% of all protein glycosylation

31
Q

What are the three components of the Golgi?

A

cis Golgi network
medial cisternae
tran Golgi network

proteins have to move through this network in endosomes
!> stationary cisternae model-vesiclules moving
2.cisternal maturation model-Sack matures into trans

Anterograde movement is ER-Golgi-plasma membrane
Retrograde Vesicleus-golgi-ER

32
Q

The three compartments of the Golgi carry out ——functions thus requiring a —-of enzymes

A

distinctive
specific set
These enzymes must have either a system for retention or retrieval

33
Q

____secretion occurs continuously

A

constitutive

34
Q

—-secretion requires specific signal

A

regulated

35
Q

Acid hydroplanes are modified by? This allows them to? What happens when the pH drops? What happens when this fails?

A

A mannose-6-phosphate(M6P) moiety in the golgi. This allows the, top binds to a M6P receptor which they are then packed into vesicles going to the lysosomes. As the pH drops, the cargo and receptor separate, with the receptor returning to the Golgi and the cargo going on to the lysosome. Failure leads to one or more hydrolases in the lysosomes, which mean cellular components are not broken down correctly. These diseases are collectively called as lysosomal storage diseases.

36
Q

Secretion via vesicles is called?

A

ecocytosis

37
Q

____can physically move vesicles around the cell. This requires any inputs of energy.

A

Motor proteins

38
Q

What are the three types are motor proteins?

A

Kinesins
dyneins
myosins

39
Q

____move towards the plus end of the mircotubules

A

kinesins

40
Q

____move towards the minus end of the mircotubules

A

dyneins

41
Q

___move along microfilaments

A

myosins

42
Q

Endocytosis

A

taking components from outside the cell in vesicles

43
Q

___is similar to endocytosis but it involves cytoskeletal rearrangements and it can be used to bring very large macromolecules even other cells into the cell

A

phagocytosis

44
Q

Selection of endocytosis can be______ or ______

A

non-selective-pinocytosis
selective-receptor-mediated

45
Q

___form the vesicle, and they may be important for cargo selection by associating directly or indirectly with receptors

A

Coat proteins

46
Q

The LDL-receptor associates indirectly with the____, allowing for selective uptake of LDL

A

coat protein clathrin

47
Q

What are the three coat proteins?

A

Clathrin
COPI
COPII

48
Q

Clathrin

A

out from the Golgi and in from plasma membrane

triskelion-3 large and 3 small polypeptides

polymerizes into a soccer ball shape
Coat assembly initiated by ARFs(GTPase)
Dynamin(GTPase) pinches off membrane

49
Q

COPI

A

back from Golgi to ER
initiated by ARF

50
Q

COPII

A

out from ER
utilizes Sar1 for initiation

51
Q

Initiation of coat formation if mediated by

A

monomeric GTPases

52
Q

Pinching off the vesicle requires a —

A

second monomeric GTPases called dynamin

53
Q

Vesicular targeting requires a third monomeric GTPas called

A

Rab

54
Q

SNARE complexes?

A

mediate membrane fusion of vesicles and target membranes.

Generally there is a single helix on a vesicle and 3 on the target membrane. These spontaneously fold into a four helical bubble when they are close. The energy released from formation is used to drive membrane fusion, which is an unfavourable process