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the patient > membrane structure > Flashcards

membrane structure Flashcards

1
Q

what is it called when lipids are not soluble in water

A

hydrophobic

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2
Q

where can bilayer be found?

A

in membrane and organelles.

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3
Q

X In spingolipids, what causes the linkage for the tail and head?

A

amino acids via an amide bond (N-c=o)

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4
Q

X in glycolipids what is attached to the amino acid

A

carbohydrates

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5
Q

X what is the importance of sphingolipids

A

importance in disease like diabetes, cancer, microbial infections

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6
Q

X what is the structural purpse of sphingolipids?

A

general protection from harmful environmental factors, adhesion for extracellular proteins (cell adhesions link cells to the extracellular matrix and to each other), signal transmission and cell recognition.

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7
Q

X what are the 3 classes of lipids

A
  1. Phosphoglycerides (e.g., phosphatidylcholine)
  2. Sphingolipids (e.g., sphingomyelin)
  3. Sterols (e.g., cholesterol)
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8
Q

what are amphipathic molecules

A

molecules with both polar and non-polar regions.

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9
Q

X what are phosphoglycerides composed of

A

polar head group, two hydrophobic fatty acid tails, 3 glycerol hydroxyl groups attaches the head to tails,

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10
Q

X how many carbons long are the two fatty acids in phosphoglycerides

A

16-18 carbons long (c-h)

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11
Q

X glycerol acts as a platform for attachment for head to tails. the two oxygens bond as the place for attachment, in which type of bond?

A

ester bond (c-o-c)

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12
Q

X what is the third oxygen bonded to in glycerol?

A

phosphate= po4

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13
Q

X the head of phosphoglycerides are polar. how does this occur?

A

phosphate -ve charge, choline +ve charge = both strongly ionic.

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14
Q

X the fatty acid tails are non-polar what does this mean?

A

no charges on fatty acids.

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15
Q

X the polar head group is composed of a phosphate group linked to another molecule like choline (alcohol) what would this be called?

A

phosphatidyl choline.

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16
Q

X what is an examples of phosphoglycerides?

A

phosphatidylcholine

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17
Q

X where do sphingolipids occur?

A

outer part of membrane (exoplasmic membrane)

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18
Q

X where can sphingolipids be found?

A

CNS and display biological function

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19
Q

X what is sphingolipids backbone made from?

A

sphingosine (head part)

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20
Q

X sphingomyelin is an example of sphingolipids. what does the structure look like?

A

sphingomyelin has a polar phosphoryl-choline head.

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21
Q

X what does the structure of sterols look like?

A

single polar HYDROPHILIC HEAD (OH), attached to steroid ring (carbon rings), and a short non-polar tail (hydrophobic attracted to tails of phospholipids in centre of membrane).

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22
Q

X what percentage of nerve cell membranes are sterols?

A

25%

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23
Q

what does lipid composition determine?

A

determines fluidity and mobility of the cell membrane.

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24
Q

what does membrane fluidity refer to?

A

the easiness of things moving in and out of the lipid bilayer of the cell membrane

25
Q

what 3 factors affect fluidity of membrane?

A
  1. saturated and unsaturated fatty acids
  2. temperature
  3. cholesterol
26
Q

what is the effect of saturated fatty acids on formation of the fatty acid tail?

A

no double bond–> straight formation of fatty acid

27
Q

what is the effect of UNsaturated fatty acids on formation of the fatty acid tail?

A

double bonds–> disruptive formation

28
Q

what is the effect of longer tail lengths?

A

increased IM (intermolecular) interactions and rigidity (bent, change shape)

29
Q

what is the effect of shorter tail length?

A

less interactions between tails and fluidity

30
Q

what is the effect of low temperature on fluidity?

A

low temperature = low energy = low fluidity

31
Q

what is the effect of warm temperature on fluidity?

A

warm temperature = more energy = more distance= high fluidity (allows membrane to adapt its shape)

32
Q

what does cholesterol molecules in the membrane act as?

A

temperature buffer

33
Q

in cold temperatures what does cholesterol do to the phospholipids and how does this affect fluidity?

A

cholesterol keeps phospholipids apart = increase membrane fluidity

34
Q

in warm temperatures what does cholesterol do to the phospholipids and how does this affect fluidity?

A

cholesterol binds lipids tighter together = decrease membrane fluidity

35
Q

what does increased phospholipid tail length mean for fluidity?

A

decreased membrane fluidity

36
Q

what does increased temperature mean for membrane fluidity?

A

increased membrane fluidity

37
Q

at high temperatures how does cholesterol affect membrane fluidity?

A

decreases fluidity

38
Q

at low temperatures how does cholesterol affect membrane fluidity?

A

increases membrane fluidity

39
Q

how does an increase in saturated fatty acid (no double bond) content affect membrane fluidity?

A

decrease membrane fluidity (increases packing between phsopholipids, straight formation stronger rigid )

40
Q

what does the subdomain of the plasma membrane contain?

A

variety of proteins (cell signalling), lipid raft (contains high concentrations of cholesterol and glycosphingolipids)

41
Q

how are lipid rafts positioned in the plasma membraned?

A

more ordered and tightly packed than the surrounding bilayer. they float freely in the membrane bilayer

42
Q

what is the difference between the plasma membrane and the bilayer membrane?

A

plasma membrane encloses the organelles (membrane for the organelles) and bilayer membrane is what encloses the whole cell.

43
Q

what’s the difference between normal bilayer and plasma membrane?

A

plasma membrane is high in cholesterol and sphingolipids therefore more compact and solid than normal bilayer

44
Q

what is the role of the plasma membrane?

A

compartmentalises (divides into categories) functions in the cell membrane like transmembrane proteins, carbs for signal recognition, G protein receptors

45
Q

X what are the types of membrane proteins? (5)

A

peripheral proteins, integral proteins, membrane bound proteins, transport proteins, glycoproteins.

46
Q

X what are the 2 types of transport proteins?

A

channel proteins, carrier proteins

47
Q

what are the functions of protein membrane?

A

JET RAT
junctions- serve to connect and join 2 cells together

enzymes- fixing (joining to active site)to membranes localises metabolic pathways

transport- responsible for facilitated diffusion and active transport

recognition- may function as markers for cellular identification

anchorage- attachment points for cytoskeleton and extracellular matrix

transduction-function as receptors for peptide hormones

48
Q

X how does the movement of phospholipids happen?

A

laterally (side to side)

49
Q

X what are the 2 characteristics of movement of phospholipids laterally?

A
  1. occurs frequently
  2. requires little energy
50
Q

X how else does movement occur of phospholipids?

A

across membrane TRANSVERSE (FLIP FLOP)

51
Q

X WHAT ARE THE CHARACTERISTICS OF FLIP FLOP TRANSVERSE MOVEMENT ?

A

SLOW MOVEMENT WITHOUT CATALYST, flipase catalyst (outer to inner), floppose (inner to outer), SCRAMBLASE catalyst flip flop at the same time, energy provided by ATP

52
Q

what are 3 characteristics of liposomes which carry drugs in the body (hydrophobic and hydrophilic drugs)?

A
  1. bilayer of amphipathic molecules
  2. hydrophobic outer layer with hydrophilic core
  3. vary in size
53
Q

what are 3 characteristics of micelle to transports drugs (hydrophobic drugs)?

A
  1. monolayer of amphipathic molecules
  2. hydrophilic outer layer with hydrophobic core
  3. smaller in size normally 2-10nm
54
Q

what type of drugs do micelles deliver ?

A

hydrophobic drugs like antibiotics, chemotherapeutic agents, anti-migraine formulations

55
Q

are liposomes natural or synthetic?

A

either

56
Q

where are hydrophobic drugs placed placed in the membrane in liposomes?

A

its placed in the lipid bilayer (in-between the two sets of tails)

57
Q

where are hydrophilic drugs contained in liposomes?

A

hydrophilic: in the aqueous core

58
Q

what can liposomes be used in?

A

chemotherapeutic agents such as doxorubicin and cytarabine for treating ovarian cancer, AIDS

the patient (8 decks)

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