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Molec and Cell > Chapter 12: Intracellular Sorting > Flashcards

Chapter 12: Intracellular Sorting Flashcards

1
Q

about what percentage of cell volume is typically consisting of the cytosol?

A

~50%

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2
Q

about what percentage of cell volume consists of the mitochondria?

A

~22%

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3
Q

This is true if the transport of a molecule to another area does not require transport through a membrane.

A

Topological equivalence

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4
Q

the nucleus is topologically equivalent to what?

A

the cytoplasm

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5
Q

The ER is topologically equivalent to what?

A

membrane-bound organelles, vesicles, extracellular space

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6
Q

What are 3 type of intermembrane transporters?

A
  1. gated transport
  2. transmembrane transport
  3. vesicular transport
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7
Q

where in the cell does gated transport typically occur?

A

cytosol –> nucleus

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8
Q

Where in the cell does transmembrane transport occur?

A

cytosol –> mitochondria, plastids, peroxisomes

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9
Q

Where in the cell does vesicular transport occur?

A

membrane-bound organelles –> other membrane-bound organelles

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10
Q

This type of transport uses budding and fusion mechanisms to transport soluble/membrane-bound molecules

A

vesicular transport

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11
Q

Where do all membranes come from?

A

pre-existing membranes

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12
Q

nuclear DNA is not _____ for a living organism

A

adequate

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13
Q

What information (in addition to nuclear DNA) is required for life?

A
  1. asymmetry info
  2. structural info
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14
Q

a membrane-bound organelle that is continuous with the nuclear envelope that focuses primarily on protein synthesis

A

rough ER

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15
Q

a membrane-bound organelle that is continuous with the nuclear envelope that focuses primarily on lipid metabolism and toxicant management

A

smooth ER

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16
Q

this is an outer membrane structure of the nucleoporins that recognize nuclear localization signals

A

cytosolic fibrils

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17
Q

this is an inner membrane structure of nucleoporins that conducts “quality control” on molecules, proteins, mRNA that must exit into the cytosol

A

nuclear basket

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18
Q

the intermembrane structure of nucleoporins

A

membrane ring proteins

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19
Q

This type of transport relies on active GTP, G-protein coupled receptors to import/export things from/to the cytosol

A

nuclear import + export

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20
Q

What are 5 transmembrane transport proteins found in the mitochondria?

A
  1. TOM Complex
  2. SAM Complex
  3. TIM22 Complex
  4. TIM23 Complex
  5. OXA Complex
21
Q

This transmembrane transport protein complex recognizes cytosolic proteins tagged with mitochondrial signal sequences; then pulls in protein to matrix

A

TOM complex

22
Q

How is TIM23 different from TIM22

A

TIM23 = multifold proteins

23
Q

This transmembrane protein passes protein through the second mitochondrial membrane into the matrix from

A

TIM23 complex

24
Q

What happens to any translocative signal sequences after the protein reaches its desired loaction

A

cleaved off

25
Q

What proteins are required to facilitate the transmembrane transport of a protein through TOM/TOC proteins?

A

hsp70 chaperones

26
Q

Energy-dependant conformational changes in import ATPases occur one which transmembrane transport protein?

A

TIM/TIC

27
Q

What is different about transmembrane transport to chloroplasts vs. mitochondria?

A
  1. uses TOC/TIC proteins
  2. has additional thylakoid space
28
Q

When present, this signal sequence tends to be exposed after the chloroplast signal sequence is cleaved off

A

thylakoid signal sequence

29
Q

What are two types of ER signals for ER-targeted proteins?

A
  1. co-translational translocation
  2. post-translational translocation
30
Q

This type of rough ER signal occurs when a growing peptide chain reveals an ER-targeting signal sequence to associate ribosomes to the ER membrane before resuming translation

A

co-translational translocation

31
Q

This type of ER signal occurs when a completely synthesized polypeptide chain/protein associates with the ER membrane via and ER-targeting signal sequence

A

post-translational translocation

32
Q

This is a receptor that binds to ER-targeted signal sequences to associate ribosomes with the ER

A

SRP (signal recognition particle)

33
Q

This protein removes the signal sequence from the ER-targeted protein after translation/translocation is complete

A

signal peptidase

34
Q

This protein recognizes the ER-targeted signal sequence in a protein to aid in integration/translocation

A

protein translocator

35
Q

In co-translational translocation, polypeptide translation resumes after what step?

A

SRP removal

36
Q

This sequence is found in membrane-associated/integrated ER-targeted proteins that indicates when to stop the “pull through” action

A

stop-transfer sequence

37
Q

In regards to membrane-associated/integrated proteins, what determines the cytosolic vs lumen portions of the protein?

A

stop-transfer sequence charge orientation

38
Q

The positive end of the stop-transfer sequence is located where?

A

cytosol

39
Q

What three proteins in the ER all guide misfolded proteins out of the ER lumen?

A
  1. lectin
  2. chaperone
  3. disulfide isomerase
40
Q

Where are misfolded ER lumen proteins guided to?

A

protein translocator complex

41
Q

What happens as a misfolded ER lumen protein is removed from the ER lumen?

A

tagged with polyubiquitin chain –> guided to proteosome –> digested

42
Q

What is the fate of a misfolded ER lumen protein?

A

proteosome digestion (NO rescue)

43
Q

What are the 3 sensors for misfolded proteins in the ER lumen?

A
  1. IRE1
  2. PERK
  3. ATF6
44
Q

What are the most common stressors that induce HSP chaperone activity?

A
  1. heat
  2. pH
  3. [O2]
45
Q

What are the results of increased misfolded ER lumen protein sensor activity?

A
  1. upregulation of HSP70
  2. translocation slowing
  3. translation slowing
46
Q

An enzyme associated with the ER phospholipid bilayer that encourages symmetrical growth of the membrane

A

scramblase

47
Q

An enzyme associated with a cell’s plasma membrane that encourages the asymmetrical, cytosolic monolayer after integrating exocytotic membranes

A

flippase

48
Q

New phospholipids are added to what side of the ER membrane?

A

cytosolic portion

Molec and Cell (18 decks)

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