Exam 4 (Topic 18) Flashcards

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1
Q

About 50% of the mass of membranes

A

Proteins

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2
Q

Membrane proteins can be

A

Transporters
Anchors
Receptors
Enzymes

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3
Q

Associate with the hydrophobic lipid interior

A

Hydrophobic regions

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4
Q

Associate with the aqueous cytosol and extracellular environment

A

Hydrophilic regions

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5
Q

Contain hydrophobic and hydrophilic regions

A

Transmembrane Proteins

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6
Q

The peptide backbone of proteins is

A

Hydrophilic (polar)

To span a membrane, this much be protected from the hydrophobic tails

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7
Q

Most common transmembrane protein structure

A

Transmembrane alpha-helix

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8
Q

What stabilizes the helix in the transmembrane alpha-helix?

A

Hydrogen bonding between the peptide backbone

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9
Q

The aloha helix maximizes the

A

number of H bonds possible

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10
Q

The hydrophobic amino acid side chains are

A

exposed to the lipid bilayer

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11
Q

Can form and channel (pore)

A

Multi-pass transmembrane proteins

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12
Q

Pores can be formed from

A

amphipathic alpha-helices

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13
Q

Transmembrane alpha helices can be

A

Single pass or Multi pass

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14
Q

Proton pump in archae bacteria found in salt marshes

A

Bacteriorhodopsin

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15
Q

Utilizes energy directly through sunlight

A

Bacteriorhodopsin

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16
Q

Contains retinal

A

Bacteriorhodopsin

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17
Q

Single light absorbing nonprotein molecule

A

Retinal

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18
Q

Retinal

A

Absorbs sunlight, changes confrormation and moves H+ across its polar interior to the outside of the cell

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19
Q

Seven helices

A

Bacteriorhodopsin

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20
Q

Beta sheets that span the membrane and create transmembrane channels

A

Beta-barrel

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21
Q

Formed from amphipathic Beta-sheets

A

Beta-barrel

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22
Q

The majority of the protein is in the cytosol but associated with the inner leaflet an amphipathic alpha-helix

A

Monolayer-associated proteins

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23
Q

The whole protein lies in the cytosol or extracellular environment

A

Lipid-linked membrane protein

24
Q

Anchored to the lipid bilayer by a covalently attached lipid group

A

Lipid-linked membrane protein

25
Q

Proteins are bound indirectly to one side of the membrane by an association with other membrane proteins

A

Protein-attached

26
Q

Proteins directly associated with the plasma membrane

A

Integral membrane proteins

27
Q

Protein indirectly associated with the plasma membrane

A

Peripheral membrane proteins

28
Q

A peripheral membrane protein

A

Protein-attached

29
Q

Integral membrane proteins

A

Transmembrane, Monolayer-associated, Lipid-linked

30
Q

Two methods to study membrane proteins

A
  1. Solubilizing proteins with detergents

2. Fluorescence Recovery After Photobleaching (FRAP)

31
Q

Small, amphipathic, lipid-like molecules

A

detergents

32
Q

Detergents aggregate in small clusters called

A

Micelles

33
Q

When detergents are mixed in great excess

A

Hydrophobic ends disrupt the plasma membrane and hydrophilic ends help membrane proteins mix with water

34
Q

Detergents

A

Solubilize membrane proteins

35
Q

FRAP process

A

Label membrane protein with GFP, Bleach the GFP fluorescence in small region of membrane with a laser, monitor how fast other proteins that were not bleached move into the area

36
Q

The cell membrane is attached to

A

An underlying cytoskeleton meshwork of fibrous proteins called the cell cortex

37
Q

Underlying cytoskeleton meshwork of fibrous proteins

A

Cell Cortex

38
Q

Main component of the cell cortex

A

Spectrin

39
Q

Long thin flexible rod about 100nm in length that makes multi-protein meshwork

A

Spectrin

40
Q

Connected to the membrane through intracellular attachment proteins that link the spectrin to specific transmembrane proteins

A

The spectrin meshwork

41
Q

Stabilizes red blood cell membrane, allows bending without breaking

A

Spectrin meshwork

42
Q

FRAP shows us

A

Membrane fluidity and Protein mobility

43
Q

Restriction of the plasma membrane

A
  1. Linkages to underlying cell cortex
  2. Linkages to proteins in the extracellular matrix
  3. Linkages to membrane proteins from other cells
  4. Mechanical barrier within the cell (Tight Junction)
44
Q

Transmembrane proteins that seal cell-cell contacts around the cell membrane

A

Tight Junctions

45
Q

Can be used to have two distinct membranes environments

A

Tight Junctions

46
Q

Have two distinct membranes environments or ends

A

Polarized cell

47
Q

Apical

A

Top- toward gut

48
Q

Basal

A

Bottom - toward blood

49
Q

Most membrane proteins have short oligosaccharides linked to them and are called

A

Glycoproteins

50
Q

Other can have long polysaccharides attached to them and are called

A

Proteoglycans

51
Q

Combination of glycoproteins, proteoglycans, and glycolipids on the non-cytosolic leaflet

A

Carbohydrate layer

52
Q

Carbohydrate layer three functions:

A
  1. Protects cell surface from mechanical and chemical damage
  2. Absorb water to be slimy, helps cells squeeze through tight spaces
  3. Prevents blood cells from sticking to each other
53
Q

Special cell surface receptors on endothelial cells that recognize glycoproteins on the neutrophil membrane

A

Lectins

54
Q

Grab the neutrophil to stop it

A

Lectins

55
Q

Lectins grab the neutrophil to stop it, the neutrophil…

A

exits the blood vessel