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DEN 7101 > Lec 9/11 > Flashcards

Lec 9/11 Flashcards

1
Q

phospholipid structure

A
  • polar head on surface, hydiphilic
  • Fatty acyl tails inward, hydrophobic, form weak noncovalent bonds
  • amphipathic(lipophilic/hydrophobic and hydrophilic)
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2
Q

unit membrane

A
  • inner leaflet(inner surface Protoplasmic or P-face)
  • outer leaflet(outer surface Ectoplasmic or E-face)
  • 1:1 phospholipid to protein ratio
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3
Q

what are proteins on inner leaflet?

A
  • phosphatidylserine(PS)

- phosphatidylethanolamine(PE)

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4
Q

what are proteins on outer leaflet?

A
  • phosphatidylcholine(PC)

- phosphatidylglycerol(PG)

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5
Q

what is apoptosis?

A
  • programmed cell death
  • stimulus or signal to undergo programmed cell death (DNA fragmentation~180bp, followed by morphological changes to cell/membranes)
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6
Q

signs of apoptosis

A

cell shrinkage, fragmentation, engulfment/degradation, no inflammation, limited tissue damage

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7
Q

signs of necrosis

A

cell swelling, organelle rupture, membrane rupture, tissue damage, inflammation

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8
Q

what happen in a healthy cell

A

PS asymmetry, active “flippase” process, slight negative charge

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9
Q

what happen in an apoptosis cell?

A

PS asymmetry lost, lippase activity lower, PS externalized–> “eat me” signal

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10
Q

annexin assay

A
  • protein binds to - charged phospholipid (PS)
  • protein is couples to fluorophore (fluorescent)
  • fluorescence can be visualized using microscopy
  • apoptotic cells will be labled and glow or fluorescent
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11
Q

EX of amphipathic molecules

A
  • phospholipids(fatty acyl tails increase membrane fluidity)
  • glycolipids
  • cholesterol(decreases membrane fluidity)
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12
Q

protein membrane components

A
  • integral/transmembrane proteins (span membrane, ion channel, transport protein), multipass(signaling), more on P-face
  • periferal proteins(mainly cytoplasmic face)
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13
Q

fluid mosaic model

A
  • come mobility of integral proteins

- limited in polarized cells(apical, basolateral)-related to cellular function

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14
Q

glycocalyx-cell coat

A
  • up to 50nm thick

- stains w/ lectins, Alcain blue (Ingrain blue)or ruthenium red

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15
Q

glycocalyx-carbohydrate chains

A

may be linked to transmembrane proteins, phospholipids

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16
Q

glycocalyxextracellular matrix(ECM)

A

may be constituent

17
Q

glycocalyx-function

A

protect cell(physical or chemical insults)

18
Q

how do nonpolar O2, uncharged polarH2O move acrsoss membrane?

A
  • freely along [] gradients

- simple diffusion(passive diffusion)

19
Q

how do ions and small molecules move across membrane?

A
  • facilitated diffusion(passive diffusion)

- along [] gradients

20
Q

2 types of membrane transport proteins(facilitate transfer of hydrophilic molecules)

A
  • channel proteins:gated, move ions

- carrier proteins: move small proteins, molecules

21
Q

channel proteins

A
  • hydrophilic pores or ion channels(>100 types, gated, few are ungated)
  • ion channel(hydrophobic aa face periphery, towards fatty acyl tails) and hydrophilic aa face inwards, toward inner channel surface
22
Q

voltage-gated channels

A
  • in ‘‘closed” position
  • closed position is more stable(refractory period is milisec, gate cant be reopened)
  • move to open position(Na+ channels, depolarization/transmission of nerve impulse)
23
Q

Ligand-gated channels

*Ion-channel linked receptors

A
  • binding of ligand triggers opening of channel

- remains open until ligand dissociates

24
Q

Ligand-gated channel

*Neurotransmitter-gated channels

A

post-synaptic neuron

25
Q

Ligand-gated channel

*Nucleotide-gated channels

A
  • cAMP in olfactory receptors

- cGMP in retinal receptors

26
Q

mechanically-gated channel

A
  • stereocilia(projections) in tectorial membrane
  • sounds create movement of basilar membrane
  • stereoilia bend
  • triggers ion channel opening
  • depolariztion and nerve transmission
  • nerve impulse translates sound
27
Q

G-protein-gated ion channel

* what is G-protein complex?

A
  • heterotrimeric GTP-binding protein

- 7 helix transmembrane, intra-, extracellular domains

28
Q

G-protein-gated ion channe

* how do extracellular ligand changes conformation?

A
  • GTP replaces GDP activating intracellular signaling

- activated protein interacts to open ion channel

29
Q

ungated channel

A
  • K+ leak channel

- creates voltage(potential) across membrane

30
Q

what is aquaporins?

A
  • impermeable to protons
  • involved in proper kidney function, clearance
  • AqpZ: passage of water
  • GlpF: passage of glycerol
31
Q

carrier proteins

A
  • bind molecules or ions on both sides
  • extra & intracellular face
  • involved reversible conformation changes
32
Q

carrier proteins-Uniport

A
  • single molecule moving one way

- GLUT1 uniport carrier-faciliated transport

33
Q

carrier proteins-symport

A
  • 2 molecules moving one way
  • SGLT(sodium-glucose linked transport) in nephron, renal glucose reabsorption, small intestine, oral rehydration therapy
34
Q

carrier proteins-antiport

A
  • 2 molecules moving opposite
  • in oral and pharyngeal cancers
  • importTryptophan (biosynthesis and metabolism substrate)
  • export Kynurenine(down regulation of CD8 or Tcell)
35
Q

what is EX of primary active transport?

A
  • Na-K pump(coupled antiport carrier protein)

- require ATP (maintain >K inside, >Na outside)

36
Q

Na-K pump

A
  • 3 Na bind inside, ATP is hydrolyzed, ATPase is phosphorylated by phosphate, phosphorylation–>conformation change–> Na is transported outside
  • 2K bind outside-> dephosphorylationof ATPase-> protein return to old conformation->K is transported inside
37
Q

secondary active transport

A
  • gradient driven
  • can be symport or antiport
  • K and glucose bind outside face of carrier protein->shape change->transfer and release into cytoplasm
38
Q

types of cell surface receptors

A
  • ion-channel linked receptors
  • enzyme-linked receptors
  • G-protein-linked receptors

DEN 7101 (5 decks)

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