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Molecular Bio - Exam I > Lect. 11 - intracellular compts. and protein sorting 1 > Flashcards

Lect. 11 - intracellular compts. and protein sorting 1 Flashcards

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Biology 101 flashcards
1
Q

plasma membrane

A

outer boundary of cells, bilayer; protective barrier, has transporters, signaling

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2
Q

plasma membrane

A

outer boundary of cells, bilayer; protective barrier, has transporters, signaling

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3
Q

nucleus

A

contains the genome; principal site for DNA and RNA synthesis

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4
Q

Cytoplasm

A

consists of cytosol and cytoplasmic organelles; intermediary metabolism

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5
Q

endoplasmic reticiulum

A

ribosomes attached to it (rER), no ribosomes (smoothER); protein sysntehsis, lipid synthesis, protein folding, storage of Ca.

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6
Q

golgi apparatus

A

stacks of disc like compartments; post-translational changes on proteins and lipids, trafficking

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7
Q

mitochondria

A

outer and inner membrane and matrix; makes ATP, signaling, cell differentiation and cell death

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8
Q

lysossomes

A

contain digestive enzymes that degrade organelles and biomolecules

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9
Q

peroxisomes

A

small vesicular compartments that contain enzymes used in oxidation reactions

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10
Q

what are the 3 topological categories of the cell?

A

nucleus and cytosol; organelles (ER, golgi, endosomes, lysosomes); mitochondria

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11
Q

gated transport

A

b/w nucleus and cytosol through nuclear pore complexes (active transport and free diffusion)

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12
Q

transmembrane transport

A

membrane protein translocators directly transport specific proteins from cytosol across an organelle membrane

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13
Q

vesicular transport

A

membrane-enclosed transport intermediates move proteins b/w various compartments via vesicle

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14
Q

what guides protein transfer/transport to various compartments?

A

sorting signals

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15
Q

make up of a sorting signal

A

stretch of aas, typically 15-60 residues long; may be localized on N or C terminus or w/i protein sequence.

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16
Q

signal patch

A

formed by multiple scattered sequences in protein

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17
Q

signal peptidase

A

may remove signal after protein reaches final destination

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18
Q

which is more important in a signal sequence; the physical properties or the actual sequence?

A

the physical properties (charge, hydrophobicity, etc. )

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19
Q

what are signal sequences recognized by?

A

complementary receptors

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20
Q

nuclear transport

A

gated, bidirectional, and selective

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21
Q

what proteins are needed in the nucleus for nuclear transport and where do they come from/where are they synthesized?

A

histones, DNA and RNA polymerases, topoisomerases, gene regulatory proteins - imported from cytoplasm - also where they are synthesized

except- tRNA and mRNA are synthesized in the nucleus and exported to the cytosol

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22
Q

Nuclear Pore Complexes (NPCs)

A

composed of 30 different proteins/nucleoporins. arranged in octagonal symmetry w/ one or more aqueous pores.

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23
Q

What direction is transport in NPCs?

A

both directions

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24
Q

What kind of transport in NPCs?

A

passive diffusion of small molecules and facilitated transport

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25
Q

How is transport facilitated in NPCs?

A

by binding of particles to fibrils extending from NPC

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26
Q

Nuclear Localization Signals (NLS)

A

sorting signals that direct molecules to nucleus; short sequences rich in positively charged aas lysine and arginine

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27
Q

where are NLS located?

A

many different sites on protein - from loops or patches on surface

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28
Q

what is the result of NLS?

A

selective import of proteins into nucleus

29
Q

what recognizes NLS?

A

nuclear import receptors (NIRs)

30
Q

Nuclear Import Receptors (NIRs)

A

soluble cytosolic proteins that bind to NLS on protein and to NPC proteins present on fibrils that extend into cytoplasm

31
Q

make up of NPC proteins

A

they have phenylalanine glycine (FG) repeats; they serve as binding sites for import receptors

32
Q

nucleus

A

contains the genome; principal site for DNA and RNA synthesis

33
Q

Cytoplasm

A

consists of cytosol and cytoplasmic organelles; intermediary metabolism

34
Q

endoplasmic reticiulum

A

ribosomes attached to it (rER), no ribosomes (smoothER); protein sysntehsis, lipid synthesis, protein folding, storage of Ca.

35
Q

golgi apparatus

A

stacks of disc like compartments; post-translational changes on proteins and lipids, trafficking

36
Q

mitochondria

A

outer and inner membrane and matrix; makes ATP, signaling, cell differentiation and cell death

37
Q

lysossomes

A

contain digestive enzymes that degrade organelles and biomolecules

38
Q

peroxisomes

A

small vesicular compartments that contain enzymes used in oxidation reactions

39
Q

what are the 3 topological categories of the cell?

A

nucleus and cytosol; organelles (ER, golgi, endosomes, lysosomes); mitochondria

40
Q

gated transport

A

b/w nucleus and cytosol through nuclear pore complexes (active transport and free diffusion)

41
Q

transmembrane transport

A

membrane protein translocators directly transport specific proteins from cytosol across an organelle membrane

42
Q

vesicular transport

A

membrane-enclosed transport intermediates move proteins b/w various compartments via vesicle

43
Q

what guides protein transfer/transport to various compartments?

A

sorting signals

44
Q

make up of a sorting signal

A

stretch of aas, typically 15-60 residues long; may be localized on N or C terminus or w/i protein sequence.

45
Q

signal patch

A

formed by multiple scattered sequences in protein

46
Q

signal peptidase

A

may remove signal after protein reaches final destination

47
Q

which is more important in a signal sequence; the physical properties or the actual sequence?

A

the physical properties (charge, hydrophobicity, etc. )

48
Q

what are signal sequences recognized by?

A

complementary receptors

49
Q

nuclear transport

A

gated, bidirectional, and selective

50
Q

what proteins are needed in the nucleus for nuclear transport and where do they come from/where are they synthesized?

A

histones, DNA and RNA polymerases, topoisomerases, gene regulatory proteins - imported from cytoplasm - also where they are synthesized

except- tRNA and mRNA are synthesized in the nucleus and exported to the cytosol

51
Q

Nuclear Pore Complexes (NPCs)

A

composed of 30 different proteins/nucleoporins. arranged in octagonal symmetry w/ one or more aqueous pores.

52
Q

What direction is transport in NPCs?

A

both directions

53
Q

What kind of transport in NPCs?

A

passive diffusion of small molecules and facilitated transport

54
Q

How is transport facilitated in NPCs?

A

by binding of particles to fibrils extending from NPC

55
Q

Nuclear Localization Signals (NLS)

A

sorting signals that direct molecules to nucleus; short sequences rich in positively charged aas lysine and arginine

56
Q

where are NLS located?

A

many different sites on protein - from loops or patches on surface

57
Q

what is the result of NLS?

A

selective import of proteins into nucleus

58
Q

what recognizes NLS?

A

nuclear import receptors (NIRs)

59
Q

Nuclear Import Receptors (NIRs)

A

soluble cytosolic proteins that bind to NLS on protein and to NPC proteins present on fibrils that extend into cytoplasm

60
Q

make up of NPC proteins

A

they have phenylalanine glycine (FG) repeats; they serve as binding sites for import receptors

61
Q

How do receptors + cargo traverse the NPC?

A

by binding, dissociating, and re-binding to adjacent FG repeats

62
Q

What does nuclear export rely on?

A

nuclear export signals (NES) on molecules that need to go out of nucleus ; need complementary nuclear export receptors (NER)

63
Q

role of NER in nuclear export

A

NER bind to cargo present in nucleus and NPC proteins; binding, dissociation and re-binding facilitates transport.

64
Q

What drives nuclear transport?

A

gradient of Ran conformational states drive nuclear transport in appropriate direction import receptor and cargo enter nucleus by interacting w/ FG repeats on NPC proteins

65
Q

Ran-GTP

A

binds to complex of import receptor and cargo; binding causes release of cargo; Ran-GTP + import receptor leave nucleus

66
Q

what happens to Ran-GTP in cytoplasm

A

Ran-GTP is hydrolyzed by Ran-GAP; receptor is released from Ran-GDP and is ready for another cycle

67
Q

Shuttling proteins

A

some proteins contain both NLS and NES; these proteins shuttle back and forth b/w nucleus and cytosol

68
Q

what is steady state localization dependent upon?

A

relative rate of transport

69
Q

if rate of import is greater than export . . .

A

it is considered nuclear and vice versa

Molecular Bio - Exam I (9 decks)

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