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Cell Biology Exam 2 > Membrane Structure and Properties Membrane Lipids > Flashcards

Membrane Structure and Properties Membrane Lipids Flashcards

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1
Q

General Functions of Membranes

A
  1. Compartmentalization (organells - membrane bound comparments - delegate function - increase effecancy)
  2. Defines a cell’s boundary (plasma membrane - seprates from exteriror)
  3. Selective Permeability(Regulates, mediates transport) (allows what gets in and what gets out of cell)
  4. Generates electrochemical gradients (change in voltage due to ion gradent often maintained by ATPases - energy investment - also directs cellular processes)
  5. Sensor of external stimuli (also internal, cell signaling pathways, adapt to changes in enviorment via receptors)
  6. Mediates adhesion (protiens - cell cell junctions)
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2
Q

Plasma Membrane

is a __ barrer that __

Protects _

is a fluid __

A

all cells have

Selective barrier that defines the cell

Protects the interior of the cell from the external environment

is a fluid mozahc - has to be cterin degree - membrain fluidity - for protines to function

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3
Q

Plasma Membrane has

A

glycome - suggar coat

membrane protines - transport, receptors, etc.

lipids, two layers - non polar in core

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4
Q

membraines are ___ assemblies of __

A

non covalant

of amipathic (or ampifillic) lipids and protines

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5
Q

Interactions of lipid bilayer

A

h bonds - polar interacts with polar

vander wals - hydrophoic interact when close

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6
Q

Phospholipids spontaneously form

A

bilayers

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7
Q

Micelle

A

single layer of lipids

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8
Q

shape of lipid

A

determines structure

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9
Q

Hydrophobic efects of lipid bilayer

A

excule hydro from enviorment - relase H2O from hydrpobic regions

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10
Q

large tear in membrane

A

requires energy to repair - not self seeling

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11
Q

small tear in bilayer creates __

and ___ to elimate (above)

only way to avoid (above) is ___

A

creates a free edge with water, which is energetically unfavorable

Lipids rearrange spontaneously to eliminate free edge

The only way to avoid free edges is formation of a sealed compartment

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12
Q

Lipid Bilayer is a __

able to __

A

2D Fluid

diffuse freely within plane of bilayer. Proteins “dissolved” in the lipid bilayer mediate functions of the membrane.

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13
Q

Lipids difuse

A

laterally

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14
Q

Lipids flip flop with

A

flippase

enzime that catolizes this

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15
Q

Lipid Flexion

A
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16
Q

Lipid Rotation

A
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17
Q

Liposomes are __

A

synthetic (artifical) lipid bilayers

formation of vesicles

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18
Q

Implcations/Uses of Liposomes

A

model systems to studdy membrane properties

delevery systems (non carriers) in drug delevery (ex. targeted way to reach cancer cells)

target specificity - specific ligans for specific cells

good carrer - ampipathic (drug of intrest water soluble also good for medications that get stuck in blood/plasma - protective coating - last longer - get to target)

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19
Q

Can liposomes fuse sponstanously?

A

NO

hydration scheels prevent this - are a barier - regulate process (so dont fues and ex. nutrents get to their targets)

have to get very clse so that fusion proties can catolize the fustion only with target membranes

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20
Q

Soap consists of

A

salts of fatty acids

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21
Q

When added to water, soap forms a

A

micelle

traps dirt on/in hydrophobic inside

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22
Q

How does soap inactivate Sars CoV2

A

Homophobic attract to hydrophobic in virus and membrane protines → loosens the bilayer → extracts protines needed for infection

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23
Q

Types of membrane lipids

A

Phosphoglycerides (glycerophospholipids)

Sphingolipids

Glycolipids (Glycosphingolipids)

Sterol

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24
Q

Fatty Acids can be___ Or ____

A

unsaturated - cis double bond - causes kink/bend

Saturated - strait - fully saturated with H

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25
Q

Unsaturated faty acids are more

A

fluid

Don’t pack as tightly

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26
Q

Trygliserides are

A

not membrane lipids

are source of energy

are neutral/have no net charge

entirely hydrophobic and therefore less bulky

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27
Q

Phosphoglycerides are the main phospholipid in __

A
  • Main phospholipid in most animal cell membranes
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28
Q

Phosphoglyceride motif

A
  • Glycerol backbone (has three carbons)
  • Fatty acid chains esterified to (glycerol C1, C2)
  • Phosphate (C3 on glycerol)
  • Alcoholic base (phosphoester linkage), known as head group
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29
Q

Head group has ___ linkage

A

phosphoester linkage

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30
Q

Phosphoglycerides are Formed from ____ Intermediates

A

Phospholipid

Phosphatidic acid (PA) & Diacylglycerol (DAG)

31
Q

Phosphatidic acid (PA) lacks ___

is an important ____

A 
Phosphatidic acid (PA) lacks base.
Important precursor intermediate during phospholipid (PL) biosynthesis in the ER.
32
Q

Diacylglycerol (DAG) lacks __

Generated during ___

A

•Diacylglycerol (DAG) lacks PO4 and base.

–Generated during Phospholipid biosynthesis and by Phospholipase C hydrolysis of polar head groups

33
Q

Serine family of alcoholic bases.

A

phosphatidylserine (PS) - Serine - Ameno Acid
phosphatidylethanolamine (PE) - Ethanolamine - via decarboxolation of Ser.
phosphatidylcholine (PC) - Choline - Via methalation of ethanolamte

34
Q

Inositol-derived Head Groups

A

PI-phosphate (PIP), PI-bis-phosphate (PIP2).

Inositol ring may be substituted with one, two, or more phosphates.

Precursors to highly-potent signaling molecules IP3.

Are smaller consenuates in bilayer

35
Q

Inositol is a ___

forms ___

A 
Inositol—a six-carbon cyclic sugar alcoholic ring.
Forms phosphatidylinositol (PI).
36
Q

Variations in head group (Phosphoglycerides)

A

Membrane surface properties of these molecules

make them important in cell recognition, signaling, and binding.

Fatty acid chains can vary in length and saturation, resulting in a variety of functions

ex. neg charge - areas consentrated with strongly negative - attracts cetrine (ex. enzimes)

37
Q

Sphingolipids

A

(Sphingosine based backbone)

38
Q

Sphingosine is an

A

amphipathic long-chain amino-alcohol hydrocarbon

Precursor to all sphingosine-based membrane lipids. Formed from serine and palmitic acid (C16 fatty acid)

39
Q

Ceramide is the __

Formed by __

is intermedate for ___

A

Simplest Sphingolipid, Pro-apoptotic molecule, and Main component of epidermis layer of skin (maintain barrier, waterproof)

Formed by addition of fatty acid to amine of sphingosine

Intermediate (foundation) for all sphingosine-based lipids.

40
Q

Sphingomyelin

A

(Major class of Sphingolipids)

Phosphocholine or phosphoethanolamine as head group

Major component
of myelin-the insulating sheath for axons

typically in extracellular leaflet

41
Q

Glycolipids

Resemble ___

___ linked to ___ by___ via ___

Found ___

A

(aka Glycosphingolipids)

Resemble sphingolipids, but instead of phosphate linked head group, they have sugar

Sugar linked to ceramide by O-glycosidic bond via the OH group of ceramide.

Found exclusively in the noncytosolic
monolayer of cell membranes

42
Q

noncytosolic

A

fasing extereor

corrospons to areas that they are made in

43
Q

Exampels of Glycolipids

A

–Cerebrosides: 1 sugar

–Gangliosides: >1 sugar with 1 or more sialic acids - neg charge. (role in cell interaction, recognition, signal transduction(voltage difference across membrane) - found more abundantly in nervous sytem

44
Q

Gangliosides

A

(charged glycolipids)-electrical effects

45
Q

Function of glycolipids

A

Gangliosides (charged glycolipids)-electrical effects
Play a role in altering the electrical field across a membrane and the concentration of ions

46
Q

Tay Sachs Disease

A

a genetic mutation alters the lysosomal (organelle containing digestive enzymes) enzyme that breaks down gangliosides, which accumulate in nerve cells - particularly in the brain

early in life - devolop normal

as progrss - delay moto function, cognitive function, and not eat, loose ability to see and hear

avg. lifespan - 5 yrs

47
Q

Sugar Abbreviations

Glc

Gal

GalNAc

Fuc

A

Glc - Glucose
Gal – Galactose
GalNAc – N-acetyl-Galactosamine
Fuc - Fucose

48
Q

basis of blood typing

A

glycolipids

are blood group antigens

49
Q

Asymmetry of Lipid Bilayer

A

Two monolayers of lipid bilayer in many membranes very different

Two differnt allow for functionality - differnt extra and intra cellular

50
Q

extracellular and cytoplasmic suffaces a symetry

A

–Phosphatidylcholine and sphingomyelin(extracellular surface)

•cellular recognition, interactions, protection, insulation.

–phosphatidylserine (cytoplasmic surface)

•negative charge - interactions with protein kinases (PKC). - due to Phosphatidylserine (relay signal transduction because attract PKC)

51
Q

Cholesterol is a

A

sterol

52
Q

Cholesterol is a

A

sterol

53
Q

Cholesterol contains __

is__

in ___

make __

A

•Contains a rigid ring structure, with attached polar hydroxyl group and short nonpolar hydrocarbon chain

is very hydrophobic

  • Only in eukaryotes
  • We make it! (synthsize on own)
54
Q

Cholesterol functions as sterioid precusor of ___

Ciritcal in mediating __

A

bile salts

sterioud hormones

and vitamin D

medating membrane fluidity

55
Q

Cholesterol is carried by __

A

lipoprotein - is a carriing device - allows cholesterol to be packaged outer - phospholipids - polar

56
Q

LDL

A

LDLs can transport cholesterol into artery walls, including arteries in the heart, arteries leading to the brain and arteries in the brain itself.

This leads to the formation of “plaques”. Plaques can slow or obstruct the flow of blood.

is a lipoprotein

57
Q

_ transports cholesterol into the artery walls

This can lead to the formation of __

A

LDLs

including arteries in the heart, arteries leading to the brain and arteries in the brain itself.

This leads to the formation of “plaques”. Plaques can slow or obstruct the flow of blood.

58
Q

The temperature at which phase transition occurs is called __

A

Phase Transition Temperature.

59
Q

Fluidity and phase temp

A

High Fluidity = Low Phase Transition Temp.
Low Fluidity = High Phase Transition Temp.

High Fluidity Means That Lipids Resist Gelling.
Low Fluidity Means That Lipids Gel Easily

60
Q

Factors Affecting Phase Transition Temperature

A

aka fluidity

Fatty acid chain length (proportonal to)

Fatty acid double bonds (inversly proportional to)

61
Q

how fatty acid chain length affects fluidity

A

Reduced chain length enhances lateral diffusion by reducing the tendency of hydrocarbon chains to interact. Gels at lower temp.

Longer chains - dec fluididty -tangled up with other - steric hindrence

62
Q

how fatty acid double bonds affects fludity

A

Double bond introduces a kink in acyl chain. - do not pack as tightly

Thus, unsaturated acyl chain containing phospholipids gel at lower temp.

63
Q

“Tight Seal” in sterols

A

Due to interactions near the head groups, sterols reduce permeability to small solutes.

64
Q

Cholesterol and Fluidity

A

is a mediator of membrane fluidity

65
Q

At normal body temperatures cholesterol

A

Interactions of rigid ring structure of cholesterol and phospholipid fatty acid tails reduces mobility of phospholipids, decreases fluidity.

66
Q

At low temperatures cholesterol

A

prevents phospholipids from packing tightly with other phospholipids, increases membrane fluidity

67
Q

changes of fluididy in diff temp with and without cholesterol

A
68
Q

Cholesterol is in these cells

A

eukaryote but NOT procaryote

69
Q

partly hydrogenated =

A
70
Q

partly hydrogenated =

A

trans fats

71
Q

trans fats

A

Partially hydrogenated vegetable oils formed by a chemical hydrogenation process

Double bond straightens the molecule

72
Q

How would trans fatty acids affect cell membrane?

A

cis to trans - no kink - behave like saturated - longer shelf life

73
Q

trans fats affects on HDL and LDL

A

Increased LDL (Bad cholesterol)

Decreased HDL (Good Cholesterol)

Cell Biology Exam 2 (6 decks)

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