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BIOL 2030 > Ch. 15 Membrane-Enclosed Organelles, Protein Sorting, Vesicular Transport, Endocytic Pathways > Flashcards

Ch. 15 Membrane-Enclosed Organelles, Protein Sorting, Vesicular Transport, Endocytic Pathways Flashcards

1
Q

draw out the major organelles of a typical cell

A

….

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2
Q

what is the cytosol and its main function

A
  • soup for organelles w cytoskeleton
  • metabolic pathways occur here
  • begin protein synthesis
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3
Q

what is the nucleus and its main function

A
  • protection centre from rest of cell due to precious material (amazon warehouse)
  • has the main genome
  • synthesizes DNA and RNA
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4
Q

what is the cytoskeleton and its main function

A
  • organizer and shape maintainer
  • keeps organelles in place
  • helps move cell during growth and motility due to dynamic abilities
  • helps during endocytosis and exocytosis
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5
Q

what is the ER and its main function

A
  • transport network (amazon delivery driver)
  • transports molecules that have specific destination
  • synthesizes proteins that go to organelles and plasma membrane
  • synthesizes most lipids
  • smooth and rough
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6
Q

differentiate between smooth and rough ER

A
  • rough has ribosomes adhered on outer surface and more responsible for protein synthesis, quality control, folding, and dispatch
  • smooth lacks outer ribosomes and more responsible for lipid synthesis, metabolism, hormone production and detoxification
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7
Q

what is the golgi apparatus and its main function

A
  • packager
  • modifications, sorting, packaging of proteins and lipids for secretion or delivery
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8
Q

what is the lysosome and its main function

A
  • garbage disposal system
  • rich in digestive enzymes
  • intracellular degradation
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9
Q

what is the peroxisome and its main function

A
  • biohazard disposal system
  • rich in digestive enzymes
  • oxidation of toxic materials
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10
Q

what is the mitochondria and its main function

A
  • powerhouse
  • ATP synthesis by oxidative phosphorylation
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11
Q

what is the chloroplasts and its main function

A
  • in plant cells
  • ATP synthesis and carbon fixation by photosynthesis
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12
Q

what is the plasma membrane and its main function

A
  • outer lining of cell (border) letting molecules in and out
  • double layer of lipids
  • channels and pumps embedded here
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13
Q

what is the endosome and its main function

A
  • collection of organelles
  • sorting of endocytosed material from Golgi to lysosome or vacuole
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14
Q

what happens to peptides after synthesis and prior to performing its duties

A

modification and transport

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15
Q

how do proteins know where to go in a cell; where can they go

A
  • due to sorting signals
  • nucleus thru nuclear pores, ER, chloroplast, mitochondria, peroxide
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16
Q

what are sorting signals

A

amino acid sequences (or part of the sequence) on proteins that direct them in transport

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17
Q

describe translocators

A
  • proteins in membrane of organelles
  • transporters when there aren’t gates
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18
Q

describe vesicles

A

cargo transporters within ER that move to other organelles

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19
Q

where do proteins that don’t have signal sequences go

A

remain in cytosol

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20
Q

draw out a normal cell and a cell with swapped signal sequences

A

….

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21
Q

ribosomes are on ERs b/c

A

ribosomes that make proteins with ER signal sequence will bind to ER

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22
Q

draw out ribosomal subunits in cytosol attaching to proteins and feeding into ER membrane, why does this happen?

A

….

  • mRNA encodes protein to target to ER
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23
Q

draw out ribosomal subunits in cytosol attaching to proteins and releasing into cytosol, why does this happen?

A

….

  • mRNA encodes the protein to remain free in cytosol
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24
Q

how is ribosome directed to ER

A

signal sequence and signal recognition particle (SRP)

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25
Q

what does SRP do

A
  • recognizes signal sequence
  • slows synthesis of protein
  • allows SRP to become bound to SRP receptor on ER making a complex (ribosome, mRNA seq incl)
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26
Q

draw out and describe the pathway of SRP

A
  • mRNA, ribosome, and ER sequence on growing polypeptide chain allow SRP to attach, slowing protein synthesis
  • other half of SRP attaches to SRP receptor in ER membrane
  • complex is near translocation channel which makes SRP displace and recycle, allowing protein to feed thru translocation channel into ER lumen
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27
Q

what are the 2 types of proteins that get released to ER

A
  • soluble (lumen of ER then modified and transported EX secreted proteins)
  • membrane (remain in ER membrane after feeding, then modified, and still remain membrane bound when transported but can also be transported to plasma membrane on cell surface)
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28
Q

draw out how soluble proteins are released into ER

A

….

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29
Q

what is the role of signal peptidase in soluble protein release in ER

A
  • as protein feeds thru translocation channel, signal sequence is held in one spot
  • signal peptidase cuts the protein right where signal sequence ends
  • protein becomes free and enters lumen
  • signal sequence remains embedded in ER membrane
30
Q

membrane proteins have stop-transfer sequences. how does that affect signal peptidase? draw out pathway

A
  • hydrophobic
  • prevents peptide sequence from entering ER lumen after cutting off at signal sequence from signal peptidase
  • stop-transferase remains embedded in membrane which keeps membrane protein embedded as well
31
Q

SRPs and SRP receptors can be considered ________ for proteins in ribosomal subunits and translocation channels on ER membranes

A

molecular matchmakers

32
Q

how are inactive translocation channels closed

A

with a protein plug

33
Q

what happens if a protein has an internal signal sequence and stop-transfer sequence; what if there are multiple signal and stop-transfer sequences?

A
  • signal peptidase does not cut peptide sequence, rather both hydrophobic sequence regions move out of translocation channel and remain embedded;
  • the protein sequence is “stitched”
34
Q

what happens to proteins once they enter ER

A
  • formation of disulfide bonds that stabilizes protein
  • protein converted to glycoprotein (glycosylated)
35
Q

what is a glycoprotein

A

oligosaccharide + amino acid

36
Q

how do oligosaccharides transfer from glycolipid, what happens with it after

A

thru dolichol, oligosaccharide unit then attaches to an amino acid on growing polypeptide chain with protein transferase enzyme

37
Q

define functions of oligosaccharides

A
  • protect protein from degradation
  • guide protein to another organelle
  • promote cell recognition
38
Q

how do soluble and membrane proteins leave ER; what happens if it is misfolded

A

thru budding transport vesicles (i.e. pinch of ER membrane); refolded by chaperone proteins

39
Q

what happens when chaperone proteins fail to refold the ER proteins properly

A

degradation of the misfolded protein

40
Q

when proteins leave ER thru transport vesicles, where can it go

A

golgi apparatus

41
Q

draw out the golgi apparatus with all layers, trans/cis face, and transport vesicles

A

…

42
Q

the entry side of golgi is called

A

cisface

43
Q

what happens to proteins once entering golgi apparatus

A
  • transport to lysosomes, cell surface (most), back to ER
  • oligosaccharide modification
44
Q

the exit side of the golgi is called

A

trans face

45
Q

draw out how proteins will move to cell surface from golgi

A

….

46
Q

what is unregulated membrane fusion

A

continuously occurring exocytosis without signal

47
Q

what is regulated membrane fusion

A

external (physiological) signal like NT or hormone, which causes transport vesicles to emerge and bring cargo in a regulated manner (EX insulin protein brought to cell based on blood glucose levels)

48
Q

define endocytosis

A

cellular ingestion of fluids, molecules, particles, other cells thru pinching mechanism (endocytic vesicles)

49
Q

define exocytosis

A

anything produced inside the cell is transported out (cleavage outwardly)

50
Q

where do endocytic vesicles bring material to

A

lysosomes (intracellular degradation)

51
Q

compare pinocytosis and phagocytosis

A

small vs large vesicles (phagosomes) formed

52
Q

describe phagocytosis

A
  • occurs within specialized phagocytic cells
  • protozoans and amoeba are still capable of this despite not having the specialized cells
53
Q

define pseudopods

A

extensions of cytoplasm and plasma membrane

54
Q

describe how phagocytosis of wbcs to bacteria occurs

A

pseudopods gradually extend and wrap around the bacterium to engulf it

55
Q

what are examples of specialized phagocytic cells w surface receptors

A
  • macrophages
  • neutrophils
56
Q

how do surface receptors on phagocytic cells work

A

when triggered (e.g. by lipids, proteins on plasma membrane target material detected by phagocytic receptors) lead to process of phagocytosis

57
Q

phagosome fuses with lysosome to make ______; this happens bc?

A
  • phagolysosome
  • allows for contents of phagosome to be broken down
58
Q

describe the roles of phagosomes

A

defense, cellular recycling

59
Q

some bacteria have evolved to be resistant to phagocytosis for reasons not quite understood. an example of this is mycoplasma tuberculosis (i.e. the bacteria responsible for TB). describe what happens when this bacteria interacts with a wbc

A
  • bacteria is recognized by wbcs and pseudopods form around but are not able to fuse around for engulfment
  • leads to a free harbour area where the bacteria can multiply
60
Q

what can be uptaken up by pinocytosis

A

fluid, macromolecules in the fluid

61
Q

pinocytosis is more likely to contain fluids in vesicles. when these vesicles transport thru the cell, there is a likeliness that they can burst. how is this avoided in cells

A

by exocytosis pathways, recycling mechanisms to ensure membrane amt stays same as well

62
Q

define receptor-mediated endocytosis

A

process that allows conc of specific molecules in animal cells to remain regulated

63
Q

draw out how LDLs (low-density lipoproteins) are able to enter the cell with the main steps

A

(endocytosis, uncoating of clathrin coated vesicles, fusion with endosome, transfer to lysosome or recycling of receptors, free cholesterol enters)…

64
Q

aside from LDLs, what other molecules are able to follow the process of receptor-mediated endocytosis

A

iron, vitamin B12, viruses (exploitation by influenza, HIV)

65
Q

draw out the possible options of what happens to endocytic material in transport vesicles after entering early endosomes

A

main points: recycling, degradation, transcytosis

66
Q

define transcytosis

A

when receptors are transferred to different region of the plasma membrane (which may have unique properties)

67
Q

draw out how lysosomes work

A

main points: internal of cell is more acidic which can break down material into individual components

transporter metabolite proteins present

H+ pump and acid hydrolases present

68
Q

describe how H+ pump works in lysosome

A

H+ ions brought into lysosome by breakdown of high energy phosphate bond in ATP into ADP+P (ATP hydrolysis)

69
Q

draw a summary diagram of endocytosis, phagocytosis, and autophagy

A

…

70
Q

differentiate late vs early endosomes

A
  • early endosomes have tubular and vacuolar domain categories
  • late endosomes are closer to the nucleus and made from vacuolar domains
71
Q

what is autophagy

A

organelles that become damaged and malfunctioned are tagged and surrounded by membrane for recycling

BIOL 2030 (16 decks)

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