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MM Block 1 > Cell Membranes > Flashcards

Cell Membranes Flashcards

1
Q

has both hydrophilic and hydrophobic elements

A

amphipathic

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2
Q

amphipathic molecules that disrupt membranes by shielding non-polar regions of memb. Removes integral membrane proteins

A

detergent

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3
Q

most common phospholipid

A

phosphatidylcholine

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4
Q

membrane sugars (glycolipids, glycoproteins, proteoglycans) are added in the _______ on the ___ face, and therefore are located on the ____ of the plasma membrane

A

added in the golgi on the lumenal face, and therefore are located on the extracellular face of the plasma memb.

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5
Q

increased membrane fluidity results from

A
  • less cholesterol (sterols increase rigidity)
  • short, unsaturated phospholipid tails
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6
Q
  • ______ can diffuse in the plasma memb.
  • ____ can easily spin in the memb (____).
  • Movement of lipids between bilayers requires ______.
  • New phospholipids are added to the _____ of the ____. ____ moves phospholipids to the other face to maintain symmetrical growth of bilayers. _____ moves specific phospholipids between cytosolic and outside bilayers.
A
  • proteins (crucial for signaling) and lipids (lateral diffusion
  • Lipids (rotation)
  • Scramblase or Flippase
  • cytosolic face of the ER. Scramblase moves phospholipids to the other side for even growth…. Flippase moves specific phospholipids…
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7
Q
  • Tethering of proteins in the plasma memb
  • Anchoring of proteins in the plasma memb
A
  • proteins bound to the cytoskeleton or to a neighboring cell
  • proteins bound to the extracellular matrix
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8
Q

Spherocytosis

  1. mechanism
  2. symptoms
  3. MOI
  4. treatment
A
  1. defect of spectrin or ankyrin in RBCs causes them to be spherical instead of bi-concave disc shaped.
  2. hemolytic anemia and jaundice
  3. AD
  4. splenectomy
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9
Q

When cells die, flippase moves ____ to the outer membrane, signaling immune cells to bind and digest the dying cell.

A

phosphatidyl serine

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10
Q

outside of the cell is topologically equivalent to:

A
  • ER
  • golgi
  • endosomes
  • lysosomes
  • vesicles
    *
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11
Q
  • proteins enter nucleus if they have:
  • prot enter mitochondria if they have:
  • prot enter ER if they have:
A
  • nuclear localization signal
  • mitochondria import sequence
  • signal sequences
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12
Q

transport into the ER is ______.

  1. _____ is created during translation. Ribosomes have a stop particle called ____ which binds the ____.
  2. The ___ binds to a ____ receptor in the memb of the ER, heping the protein bind to a ____.
  3. ______ is released from ____ and translation resumes.
  4. After translation and translocation, ____ cleaves the signal peptide
A

co-translational; transmembrane protein transport

  1. A signal peptide is created during translation. Ribosomes have a Signal Recognition Particle (SRP) which binds the signal peptide, stopping translation.
  2. SRP then binds to an SRP receptor in the memb of the ER, helping the prot bind to a translocation channel.
  3. signal peptide is released from SRP and translation resumes.
  4. signal peptidase
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13
Q

______ is provided in the translocation channel in the ER membrane, and can be activated by _____, which cause the nascent chain to stop within the channel and allows the protein to be _____.

A

lateral escape hatch

stop transfer sequences

stitched into the ER memb.

multiple stop transfer sequences give a multipass memb protein

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14
Q

examines newly synthesized proteins in the ER and destroys misfolded proteins.

Stays int he ER because it has a ____ sequence, which is recognized by ______ in the golgi and brought back via ____ if found.

A

BiP

KDEL

KDEL receptor

brought back via transport vesicles coated with COP1

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15
Q

vesicles coated with COPII move them from________.

Clathrin is involved with:

COPI coats _____ to move them _____.

A

the ER to the cis golgi

endocytosis and post-golgi transprot

golgi to ER; within golgi

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16
Q

Nuclear import: Gated transport

  1. protein with NLS binds _____ and _____ in cytosol
  2. goes thru nuclear pore
  3. _____ exchanges ____, cargo is delivered to the nucleus.
  4. _____ exits the nuclear pore.
  5. _____ hydrolyzes it ____, freeing the
A
  1. protein with NLS binds importin and Ran-GDP in cytosol.
  2. protein goes thru nuclear pore
  3. RAN_GEF exchanges GDP for GTP, so cargo is released (delivered to nucleus).
  4. Importin-Ran-GTP exits the nucleus.
  5. Ran-GAP hydrolyzes it, freeing Ran-GDP, Importin.
17
Q

Ran ____ is present in the nucleus, while Ran ___ is present in the cytosol. Therefore, there is more Ran-GTP in the ____ and more Ran-GDP in the ____.

A

Ran- GAP in the cytosol; Ran-GEF in the nucleus

more Ran-GTP in the nucleus, more Ran-GDP in the cytosol.

18
Q

Nuclear Export:

A
  1. Exportin and Ran-GTP binds protein with NES.
  2. cargo-Exportin-Ran-GTP exits the nucleus.
  3. Ran-GAP hydrolyzes to Exportin-Ran-GDP, freeing the cargo (cargo delivered to cytosol) and Ran-GDP
  4. Exportin goes back into the nucleus
19
Q

NLS has _____ which associates with channel lining including _____

A

KKKRK

Phe-glycine repeats

20
Q

amphipathic or not:

  1. phosphatidyl serine
  2. cholesterol
  3. triacylglycerol
  4. phosphatidylethanolamine
  5. detergent in tide
A
  1. phosphatidyl serine- amphipathic
  2. cholesterol- amphipathic
  3. triacylglycerol- not amphipathic
  4. phosphatidylethanolamine-amphipathic
  5. detergent in tide-amphipathic
21
Q

Vesicle budding:

  1. Clathrin binds to membrane via ____.
  2. ___ wraps around the stalk to pull vesicle free
  3. Once free, clathrin dissociates.
A
  1. Clathrin binds to membrane via adaptin and forms budding vesicle.
  2. Dynamin wraps around stalk to pull vesicle free.
  3. Clatrin dissociates
22
Q

Vesicle fusion:

  1. _____ and _____ are on the vesicle. ____ binds target and pulls vesicle clsoe so that _____ can engage with ______ on target membrane.
  2. ______ and ______ pull membranes together and exclude water, allowing membranes to fuse.
A
  1. V-Snare and Rab are on the vesicle. Rab binds target and pulls vesicle clsoe so that V-snare can engage with T-snare on target membrane.
  2. V-Snare and T-Snare pull membranes together and exclude water, allowing membranes to fuse.
23
Q

regulates COPI and clathrin in golgi

A

ARF

24
Q

regulates COPII in ER

A

SAR1

25
Q

for vesicular transport to lysosomes, ____ is added in the ____.

A

m-6-p signal added in the golgi

26
Q

protein transport into the mitochondria:

  1. ____ (outer) and ____ (inner) form translocation channel
  2. _____ (outer) and _____ (inner) help insert proteins into the memb.
  3. ______initiates transport. Protein is unfolded, transported into the nucleus, and then refolded in the nucleus w the help of _______ proteins.
  4. After translocation,_______.
A
  1. TOM and TIM form translocation channel.
  2. SAM (outer) and OXA (inner) help insert proteins into the memb.
  3. Signal sequence/mitochondrial import sequence initiates transport. Protein is unfolded, transported into the nucleus, and then refolded in the nucleus w the help of chaperone proteins.
  4. After translocation, signal sequence is cleaved and degraded.
27
Q

vesicles are guided to the plasma membrane by

A

MT tracks guide vesicles

28
Q

m-6-p receptors dissociate from protein and are recycled in:

A

prelysosomes

29
Q

Rab proteins are

A

GTPases. After fusion of membrane, Rab dephosphorylates, Rab-GDP is pulled off vesicles, and then Snares can be pulled apart by adaptors-NSF+ATP

30
Q

ARF is:

SAR1 is:

regulation of SAR:

A

a GTPase that regulates COPI and clathrin in the golgi

a GTPase that regulate COPII in the ER.

SAR1-GEF-GTP assembles at ER membrane. Recruits COPII. Buds form from ER.

31
Q

GPI-linked proteins _____ membrane fluidity

A

increase

32
Q

Calcineurin is a _______ activated by ___ which ____ the NLS in ______, which are transcription factors important to _____. This _____ the NLS, which goes to the nucleus and turns on genes in ____.

When ___ levels fall, NES is available and a _____ phosphorylates _____, blocking the _____, so it leaves the nucleus.

A

phosphatase activated by Ca which dephosphorylates the NLS in NF-AT, which are TFs important to the **immune system. **This unmasks the NLS, which goes to the nucleus and turns on genes in **T-cells. **

When Ca levels fall, NES is available and a kinase phosphorylates NF-AT, blocking the NLS, so it leaves the nucleus.

33
Q

Cyclosporine inhibits ____ signaling by suppressing ____. As a result, the _____ is blocked, preventing ____ from driving immune responses.

A

Cyclosporine inhibits NF-AT signaling by suppressing Calcineurin. As a result, the NLS is blocked, preventing NF-AT from driving immune responses.

MM Block 1 (15 decks)

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