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Pharmacy BSI > BSI Lecture 14 Endo/Exocytosis > Flashcards

BSI Lecture 14 Endo/Exocytosis Flashcards

1
Q

The cell is a dynamic entity that is not only performing specific functions but constantly ______ itself.

A

renewing

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2
Q

What are the pathways that proteins can go after they are synthesized?

A

1) It can be taken into the nucleus via pores
2) It can travel and become a part of the rough ER membrane
3) It can travel to the golgi apparatus and be packaged for intracellular transport or be exported out of the cell

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3
Q

Proteins carry “sorting signal” which are sequence of amino acids that code for their _______.

A

location

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4
Q

Proteins going to the nucleus binds to nuclear ____ _____.

A

transport receptors

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5
Q

Nuclear transport receptor actively transport proteins through the nuclear pores using what energy source?

A

GTP hydrolysis

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6
Q

The nuclear membrane contains large pores to allow access: _____ proteins must be transported in

A

specific

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7
Q

T or F; Small molecules can diffuse in and out freely through nuclear membrane.

A

true

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8
Q

Large molecules must be specifically transported through a disordered “tangle” of fibers that act as a filter to get into the nucleus, these pores are complex structures composed of more than ____ different proteins.

A

30 - 50

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9
Q

Proteins carrying nuclear localization signals, are recognized by a nuclear transport receptor, then binds to nuclear pore fibrils and transports the complex through the pore into the nucleus. The hydrolysis of _____, provides the energy for this transport which can be very rapid.

A

GTP

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10
Q

Mitochondria are thought to have been “______” sometime during evolution as separate organisms.

A

acquired

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11
Q

Mitochondria have their own DNA and are inherited as complete entities from your ______ in the ovum.

A

mother

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12
Q

Proteins targeted for mitochondria have a specific C-terminal sequence which allows their recognition and subsequent translocation through the mitochondrial membranes at specialized sites where the 2 membranes touch. T or F?

A

false, N-terminus

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13
Q

Mitochondria: The targeting sequence of the protein is removed, which sometimes reveals a new “sorting code” that further specifies their final location. T or F?

A

true

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14
Q

Mitochondria: Proteins going through the membrane needs to be ______ to pass through specialized sites.

A

unfolded

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15
Q

Proteins that unfold to go through a membrane specialized sites are refolded by ________ proteins.

A

chaperone

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16
Q

The ____ is the most extensive membranous organelle which not only requires many proteins for its own function but produces and packages membranes and macromolecules for use in other organelles, (Golgi Apparatus, endosomes, lysosomes, cell membrane), and cellular export.

A

endoplasmic reticulum

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17
Q

Transmembrane proteins only partially translocate and remain embedded in the ER membrane regardless of final specific membrane destination. T or F?

A

true

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18
Q

Protein synthesis often starts in the cytoplasm on “free” ribosomes, (rRNA), but a signal sequence is recognized by the signal recognition particle, (SRP), which directs the ribosome to the ____ membrane

A

endoplasmic reticulum

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19
Q

Less than 100 Amino Acids is a ______.

A

peptide

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20
Q

Greater than 100 Amino Acids is a _____.

A

protein

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21
Q

Proteins with a TMD, a “hydrophilic start” sequence, (followed by an appropriate “stop” sequence), allows the partially translocated peptide/protein to form an appropriate hydrophobic alpha-helix within the membrane and be retained: only one TMD is formed as the “start” sequence is now removed. T or F?

A

false, hydrophobic start sequence

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22
Q

Translocation mechanism for a protein destined to remain incorporated into a membrane with 2 TMD’s differs with one with only 1 TMD is due to the specific amino acid signaling sequences that _____ or _____ _____ the “start” sequence.

A

retain; don’t retain

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23
Q

Can the ER modify proteins?

A

yes

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24
Q

The “faces” of the vesicles are preserved therefore: cytoplasmic vs. extracellular means it is destined for the ____ ______

A

cell membrane

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25
Q

The “faces” of the vesicles are preserved therefore: cytoplasmic vs. “intraorganelle,” means it is destine for the ________.

A

organelle

26
Q

The destination of a vesicle is determined by ______ associated with it

A

protein

27
Q

How are vesicles formed?

A

“Cargo molecules” (proteins to be transported) are recognized by receptors which, via adaptin, organize clathrin molecules to form a supporting “cage” helping form the vesicle. After dynamin pinches off the vesicle the clathrin is removed and recycled leaving the naked vesicle.

28
Q

_____ protein uses ____ hydrolysis to form a “neck” around the forming vesicle and helps it pinch off.

A

Dynamin; GTP

29
Q

The contents of vesicles, (not embedded proteins), are determined by proteins from the _____ family.

A

adaptin

30
Q

Describe the mechanism of vesicle fusion.

A

a tethering protein on the cell membrane grabs the rab protein in the vesicle. It pulls it down and the t-SNARE on the cell membrane attaches to the v-SNARE on the vesicle. This causes fusion into the cell.

31
Q

Vesicles are then transported to their correct destinations via _____ motors. Does this require ATP?

A

molecular; yes

32
Q

identification of the correct destination of a vesicle depends on low molecular weight G-proteins of the ____ family

A

Rab

33
Q

“Tethering proteins” on the target membrane recognizes the ____ on surface of the vesicles.

A

Rab

34
Q

Vesicles: Additional recognition is via the _____ proteins: ____ on vesicles bind to complementary______ on target membranes and draw them closely together, excluding water, to promote fusion.

A

Rab; v-SNARE; t-SNARE

35
Q

the Golgi Apparatus is composed of groups of _ to ____ flattened and stacked membranous sacks, (cisternae), which vary widely in size and shape.

A

3;20

36
Q

How are movement between layers of the Golgi apparatus achieved?

A

by budding and subsequent fusion of vesicles

37
Q

Exocytosis: Constitutive secretions occurs ______ to renew the plasma membrane or for unregulated export.

A

continuously

38
Q

Exocytosis: Regulated secretions requires a _____.

A

signal

39
Q

Exocytosis results from the fusion of vesicles released from the cis Golgi Apparatus with the cell membrane. T or F

A

false, trans

40
Q

Constitutive exocytosis fusion with the cell membrane also releases the contents extracellularly and is therefore responsible for ____ secretion.

A

unregulated

41
Q

In addition there exists a regulated exocytosis pathway found only in cells with specialized secretory functions such as endocrine cells: vesicles accumulate near the cell membrane awaiting the appropriate signal for release, (often an increase in intracellular calcium: ↑[Ca2+]i). T or F?

A

true

42
Q

The constant addition of new cell membrane is typically matched by a constant recycling of the cell membrane which maintains the size of the cell/surface area of the membrane. T or F?

A

true

43
Q

Endocytosis is the reverse of exocytosis: the cell membrane invaginates to form a new inward, budding vesicle in order to import substances and associated fluid; this is specifically____ .

A

pinocytosis

44
Q

Some specialized cells can ingest old cells, (for recycling), malfunctioning cells, (cancerous), and even invading pathogens such as bacteria, (macrophages and neutrophils: see Immunology): this is _____.

A

phagocytosis

45
Q

Just as the plasma membrane is constantly renewed, so are all the intracellular organelles by a process known as ____: if this process is disrupted it can be fatal.

A

autophagy

46
Q

The internalized vesicle, (endosome/phagosome/autophagosome), often ends up fusing with a lysosome for_____ ______ prior to recycling.

A

enzymatic digestion

47
Q

Pinocytic vesicles are normally <150 nm in diameter whereas a phagocytic vesicle, known as a phagosome, is typically >250 nm in diameter. T or F?

A

true

48
Q

Phagocytosis is ______ and requires recognition via surface proteins/glycoproteins.

A

specific

49
Q

Phagocytic cells extend arm-like projections of their cell membranes called _____ which form the intracellular phagosome after internalization.

A

pseudopods

50
Q

How many RBCs do macrophages ingest a day?

A

10^11 every day

51
Q

_________, like the constitutive exocytosis pathway, occurs constantly recycling the cell membrane

A

Pinocytosis

52
Q

Vesicle formation is aided by _____-_____ pits.

A

clathrin-coated

53
Q

A specific endocytosis pathway known as _____-_____ endocytosis requires recognition by specific cell surface receptors: this is an efficient system for concentrating a substance within a cell, (x1000 compared to constitutive pinocytosis).

A

receptor-mediated

54
Q

LDLs are recognized by cell-surface receptors and are internalized via a clathrin-coated vesicle during receptor-mediated exocytosis. T or F?

A

false, endocytosis

55
Q

Receptor-mediated endocytosis is also used for the uptake of essential metabolites such as vitamin ____ and _____

A

B12; iron

56
Q

Some pathogens utilize _______-______ endocytosis pathway to gain access to cells such as the influenza viruses and HIV.

A

receptor-mediated

57
Q

Endosomes are another organelle system composed of membranous tubules and large vesicles, (the “import” equivalent of the ER and Golgi?), which functions as a “_____ _____” for endocytotic vesicles.

A

sorting station

58
Q

lysosomes contain many acid _______ (optimized for ↓pH) which degrade substances which are then recycled via transporters.

A

hydrolases

59
Q

Name the acid hydrolases in the lysosomes.

A

nucleases, proteases, glycosidases, lipases, phosphatases, sulfatases, phospholipases

60
Q

Endosomes maintain an ____/____pH which can cause the dissociation of some receptors but some are retained and later degraded in lysosomes while others continue to travel with their “cargo” to a different region of the cell membrane, (transcytosis).

A

acid/low

61
Q

_________ can either transfer material to a lysosome or a “late” _______ which may “mature” into a lysosome where full digestion via acid hydrolases occurs.

A

endosomes; endosome

62
Q

What do chaperones do?

A

attempt to refold a misfolded protein

Pharmacy BSI (58 decks)

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