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Biochemistry > Membranes and Transport > Flashcards

Membranes and Transport Flashcards

1
Q

What are membranes composed of?

A
  • lipids: messenger, drafts, protection
  • proteins: channels, transporter/carrier, receptor
  • cholesterol -> carbohydrates: cell to cell recognition
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2
Q

What are examples of phospholipids?

A
  • glycerophospholipids
  • sphingolipids-> sphingomyelin
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3
Q

What are glycolipids?

A

carbohydrates associated with lipids

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4
Q

What is the backbone of glycerol?

A
  • 2 fatty acid chains
  • alcohol
  • phosphate group
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5
Q

What type of fatty acid is at C1 in glycerophospholipids?

A

saturated

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6
Q

What type of fatty acid is at C2 in glycerophospholipids?

A

unsaturated (has a kink)

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7
Q

What are the different types of alcohols that can be esterified?

A
  • choline
  • ethanolamine
  • serine
  • glycerol
  • inositol
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8
Q

What are the types of glycerophospholipids?

A
  • in most membranes: cephalin & lecithin
  • in mitochondrial inner membrane: cardiolipin
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9
Q

On phosphatidylinositol, where can a phosphate group be attached?

A

on C3, C4, or C5

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10
Q

What are the functions of phosphatidylinositol?

A
  • source of second messenger
  • control of membrane traffic in endosomes
  • endo & exocytosis
  • activation of membrane ion channels
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11
Q

When do diseases become involved with phosphatidylinositol?

A

when an enzyme is deficient

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12
Q

What types of lipids give a cylindrical membrane shape?

A
  • phosphatidylcholine (lecithin)
  • phosphatidylserine
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13
Q

What types of lipids give a inverted conical membrane shape (positive)?

A
  • lyso-GPLs
  • phosphoinositides
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14
Q

What types of lipids give a conical membrane shape (negative)?

A
  • phosphatidylethanolamine (cephalin)
  • phosphatidic acid
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15
Q

What are the characteristics of sphingolipids?

A
  • found in the brain and nervous tissue
  • backbone: sphingosine
  • polar head & nonpolar tail
  • function: structural, adhesion site for extracellular proteins, signal transduction
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16
Q

What type of alcohol is sphingosine?

A

C18 unsaturated alcohol

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17
Q

What is ceramide?

A
  • derivative of sphingosine
  • long chain fatty acid on amide linkage to sphingosine
  • important secondary messenger
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18
Q

What is sphingomyelin?

A
  • derivative of sphingosine
  • primary OH group of ceramide is esterified to phosphorycholine
  • protects exons of neurons
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19
Q

What is the order of sphingosine and its derivatives?

A

sphingosine -> ceramide -> sphingomyelin

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20
Q

What are the diseases associated with sphingolipids?

A

Alzheimer’s & HIV related dementia

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21
Q

What are the steps for Alzheimer’s disease

A
  1. Lipid rafts bring BACE1 & gamma-secretase together
  2. BACE cleaves APP to produce A-beta fragment
  3. A-beta binds ganglioside (ceramide + sugar) to form a fibril
  4. Sphingolipids internalize the fibril into the neurons = toxic
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22
Q

Oligosaccharides covalently bond to what 2 things?

A
  • lipids -> glycolipids
  • proteins -> glycoproteins
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23
Q

What are cerebrosides?

A

glucose or galactose linked to ceramide

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24
Q

What are ceramide oligosaccharides?

A

ceramides with 2 or more neutral monosaccharides

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25
Q

What are gangliosides?

A

ceramide oligosaccharides with 1 or more sialic acid

26
Q

Oligosaccharides from what type of bonds?

A

hydrogen

27
Q

What is the purpose of lipids rafts?

A

segregate and converge to modulate the activity of membrane proteins

28
Q

What is meant by microenvironments?

A

constantly change -> formation and dispersion

29
Q

What is a sphingolipid in a microdomain?

A

lateral segregation wihtin membranes

30
Q

What are the 2 types of proteins?

A

integral & peripheral

31
Q

What are the 2 types of integral membrane proteins?

A

transmembrane & lipid anchored

32
Q

What are the types of lipid anchors in peripheral proteins?

A
  • myristoyl
  • thioester
  • thioether linked
  • glycosylphosphatidylinositol
33
Q

What are examples of peripheral proteins?

A

actin spectrin & protein kinase C

34
Q

What is the purpose of a hydropathy plot?

A
  • predict hydrophobic and hydrophilic regions in a peptide sequence
  • allows for visualization of hydrophobic regions in a protein and predict its structure
  • visualize membrane-spanning segments
35
Q

In a hydropathy plot, what size window predicts surface-exposed regions?

A

short window sizes 5-7

36
Q

In a hydropathy plot, what size window finds transmembrane domains?

A

large window sizes 19-21

37
Q

In a hydropathy plot, what does it mean to be above the line? Below?

A
  • above = hydrophobic
  • below = hydrophilic
38
Q

Is cholesterol hydrophobic or hydrophilic?

A

hydrophobic

39
Q

What is the function of cholesterol?

A
  • maintains fluidity and increases stability
  • disrupts tight packing of hydrocarbon tail
  • reduces permeability of hydrophilic molecules
40
Q

What type of architecture are plasma and intracellular membranes?

A

lipid bilayer

41
Q

What is the fluid mosaic model composed of?

A
  • has lipid bilayer
  • integral proteins
  • cholesterol moeities in between phospholipids
  • oligosaccharide chains
42
Q

What is essential for cellular function?

A

membrane fluidity

43
Q

What does the degree of fluidity depend on?

A

temperature

44
Q

What is cholesterol’s role in membrane fluidity?

A

reduce felxibilty but prevents tight packing of phospholipids

45
Q

What cannot diffuse through a membrane?

A

macromolecules & charged molecules

46
Q

What are the carrier proteins needed for passive and active transport?

A
  • uniporter (single molecule)
  • symporter (multiple molecules -> same direction)
  • antiporter (multiple molecules -> opposite direction)
47
Q

Phospholipids undergo what type of diffusion?

A

lateral

48
Q

What are the types of passive transport?

A

diffusion & facilitated transport

49
Q

In what direction does passive transport go in?

A

in direction of gradient -> from high to low electrochemical gradient

50
Q

Which type of transport uses ATP and which does not?

A
  • passive does not
  • active does
51
Q

In what direction does active transport go in?

A

in opposite direction of gradient -> from low to high electrochemical gradient

52
Q

What is a ceramide oligosaccharide?

A

ceramides with 2 or more neutral monosaccharides

53
Q

What is a ganglioside?

A

ceramide oligosaccharide with 1 or more sialic acid

54
Q

What can lead to post translational modification?

A

oligosaccharide chains attached to polypeptide side chains

55
Q

What is an example of endocytosis in active transport?

A

cholesterol transport with LDL

56
Q

What is an example of exocytosis active transport?

A

insulin secretion

57
Q

What are the receptor-related diseases associated with membrane defects?

A
  • type 2 familial hypercholesteremia
  • graves disease
58
Q

What are the structural instability diseases associated with membrane defects?

A
  • red cell abnormalities
  • alzheimer’s
59
Q

What are the altered permeability/transport diseases associated with membrane defects?

A
  • cystic fibrosis
  • connexin 26-hearing loss
  • pendred syndrome
  • Wilson’s disease
60
Q

In a hydrophobic plot, where are the hydrophilic and hydrophobic regions located?

A
  • hydrophilic -> below the line
  • hydrophobic -> above the line

Biochemistry (20 decks)

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