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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
What proteins are required to facilitate the transmembrane transport of a protein through TOM/TOC proteins?
hsp70 chaperones
26
Energy-dependant conformational changes in import ATPases occur one which transmembrane transport protein?
TIM/TIC
27
What is different about transmembrane transport to chloroplasts vs. mitochondria?
1. uses TOC/TIC proteins 2. has additional thylakoid space
28
When present, this signal sequence tends to be exposed after the chloroplast signal sequence is cleaved off
thylakoid signal sequence
29
What are two types of ER signals for ER-targeted proteins?
1. co-translational translocation 2. post-translational translocation
30
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
co-translational translocation
31
This type of ER signal occurs when a completely synthesized polypeptide chain/protein associates with the ER membrane via and ER-targeting signal sequence
post-translational translocation
32
This is a receptor that binds to ER-targeted signal sequences to associate ribosomes with the ER
SRP (signal recognition particle)
33
This protein removes the signal sequence from the ER-targeted protein after translation/translocation is complete
signal peptidase
34
This protein recognizes the ER-targeted signal sequence in a protein to aid in integration/translocation
protein translocator
35
In co-translational translocation, polypeptide translation resumes after what step?
SRP removal
36
This sequence is found in membrane-associated/integrated ER-targeted proteins that indicates when to stop the "pull through" action
stop-transfer sequence
37
In regards to membrane-associated/integrated proteins, what determines the cytosolic vs lumen portions of the protein?
stop-transfer sequence charge orientation
38
The positive end of the stop-transfer sequence is located where?
cytosol
39
What three proteins in the ER all guide misfolded proteins out of the ER lumen?
1. lectin 2. chaperone 3. disulfide isomerase
40
Where are misfolded ER lumen proteins guided to?
protein translocator complex
41
What happens as a misfolded ER lumen protein is removed from the ER lumen?
tagged with polyubiquitin chain --> guided to proteosome --> digested
42
What is the fate of a misfolded ER lumen protein?
proteosome digestion (NO rescue)
43
What are the 3 sensors for misfolded proteins in the ER lumen?
1. IRE1 2. PERK 3. ATF6
44
What are the most common stressors that induce HSP chaperone activity?
1. heat 2. pH 3. [O2]
45
What are the results of increased misfolded ER lumen protein sensor activity?
1. upregulation of HSP70 2. translocation slowing 3. translation slowing
46
An enzyme associated with the ER phospholipid bilayer that encourages symmetrical growth of the membrane
scramblase
47
An enzyme associated with a cell's plasma membrane that encourages the asymmetrical, cytosolic monolayer after integrating exocytotic membranes
flippase
48
New phospholipids are added to what side of the ER membrane?
cytosolic portion

Molec and Cell (18 decks)

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