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BCH4024 > Lipids by Ziele > Flashcards

Lipids by Ziele Flashcards

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1
Q

what are the three roles of lipids

A

energy storage; structure; signaling

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2
Q

what percent of biological membranes are made up with structural lipids

A

50%

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3
Q

why are lipids a good energy source

A

they can be packed very densely thus allowing a lot of energy to be stored within them

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4
Q

describe the difference between human and plant energy consumption

A

plants cannot store energy as fat/ lipids and rely on carbohydrates which are not as energy dense and require water; therefore animals are able to move since they have larger stores of energy

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5
Q

what part of the plant is rich in fat and why

A

seed because mobile

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6
Q

how do fatty acids act as neurotransmitters

A

they are secreted by the nervous system and bind to cannabinoid receptors to prevent activation of inhibitor neurons

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7
Q

what is the basic lipid molecule and its two forms?

A

fatty acids: saturated (straight line, no double bonds) unsaturated (kinky, double bonds)

fatty acids begin with a carboxylic acid follow by carbon chains

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8
Q

what conformation do unsaturated fatty acid double bonds lie in

A

cis conformation

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9
Q

describe the IUPAC naming of fatty acids

A

in front of the name, the number of carbons: number of double bonds (delta^position numbers of double bonds) cis- xyz

ex. 20:5 (delta ^ 5, 8, 11, 14, 17)

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10
Q

describe the omega system of naming fatty acids

A

starting at the omega carbon (farthest from the alpha) count in until you hit your first double bond and the naming would be omega - #

ex. omega-6 if first double bond is at the sixth carbon with C1 being the omega carbon

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11
Q

describe the phenomenon with melting point and saturated v unsaturated fatty acids

A

saturated fatty acids have a higher melting point than unsaturated fatty acids because of the

hydrophobic effect (fatty acids won’t come together as straight carbon chains)
van der Waals interactions (for saturated: strengthen interactions when close together and repel water/ melting)

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12
Q

what is the trend for melting point and saturated fatty acids

A

as you increase the number of carbons, melting point increases

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13
Q

what is the trend for melting point and unsaturated fatty acids

A

mp decreases as the number of double bonds increases
but increases with increasing C and not changing double bond amounts

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14
Q

describe the solubility of saturated and unsaturated fatty acids

A

solubility rules some for both types; insoluble in water but soluble in organic solvent (ex. benzene)

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15
Q

what are triacylglycerols (TAG)

A

aka triglycerides
3 fatty acids in ester linkage to glycerol
non polar, hydrophobic, neutral
function: fat storage for energy and heat production as well as thermal insulation

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16
Q

what are glycerophopholipids

A

structural lipid
2 fatty acids (U or S) with any alcohol head group, glycerol, and ester linkages

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17
Q

what are sphingolipids

A

structural lipid
sphingosine (amino alcohol) + amide linked fatty acid + polar head group (glycosidic or phosphodiester bond)

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18
Q

what are some common signaling molecules

A

cholesterol, prostaglandins (mediate swelling), cholesterol derived hormones (ex. cortisol)

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19
Q

how can we attack esters?

A

hydrolysis to form carboxylic acid and alcohol

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20
Q

what are the two major components of all membranes

A

lipids and proteins

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21
Q

what are some important properties of proteins? what allows these properties?

A

flexible, transport materials in and out, semi permeable self sealing

non covalent interactions

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22
Q

what are important characteristics of biological membranes

A

define external boundaries, control molecular traffic, divide cells/ organelles, organize reaction sequences, communication, transporters, receptors, adhesion molecules, and energy transduction

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23
Q

what is the thickness of membrane

A

50-80 angstrom

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24
Q

what do fatty acids/ lysolipids form in term of membranes

A

micelle with cone shaped subunits

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25
what do glyserophospholipids and sphingolipids form in term of membranes
bilayer with cylindrical subunits and a vesicle in the inside
26
what can you use to open micelle
SOS/ detergent molecules 12C with sulfur head
27
what are the protein components of membranes?
1. integral membrane proteins 2. peripheral membrane proteins
28
descrive integral membrane proteins
monotopic or polytopic (thought one or both leaflets of bilayer) removable only by hydrophobic agent
29
describe peripheral membrane proteins
electrostatic/ hydrogen bonding, released by detergents or by interfering with charge interact with hydrostatic interaction stay in contact with another protein or heads on lipids, not attached
30
describe amphitropic proteins
interact reversibly with membrane; bound to membrane makes it inactive while activated when off
31
what are the two techniques to study protein topology
in silico (analysis of primary amino acid sequence) in vitro (determined experimentally)
32
what type of amino acids would be inside versus outside the cell or membrane
inside the cell would be hydrophobic AA outside the cell would be hydrophilic (O/ N linked sugars) inside the membrane is mostly non polar/ uncharged AA
33
describe a type 1 (glycophorin) integral membrane protein
alpha helix structure with the amino terminus on the outside of the cell and the carboxyl terminus on the inside, goes through cell once
34
describe a type III integral membrane protein (bacteriorhodopsin)
multiple alpha helices in the membrane, amino terminus outside and carboxyl terminus on the inside acts as a proton pump in archea that live in high salt, low O2 environments
35
what can be used to predict 3D structure of a membrane protein?
hydropathy index where delta G < 0 shows hydrophilic AA and delta G > 0 shows hydrophobic
36
describe a hydropathy plot
residue number (x) v hydropathy index (y) shows areas of hydrophilicity and hydrophobicity
37
describe topology rules
1) positive inside rule (+ charged amino acids on the inside of the cell) 2) high levels of tyrosine and tryptophan found at membrane interface (due to slight hydrophilicity bc of OH & NH and amphiphatic behavior )
38
describe proteins with beta barrel structure
difficult to predict, have aqueous pore in center
39
how can membrane proteins associate with membranes
by covalently attached lipids
40
how can proteins be attached to a membrane post translation
carbon chain can be attached to a protein in order to target and attach that protein to the membrane
41
describe a liquid ordered state (Lo)
when temperature is below the melting point and is rigid/ gel like/ stick of butter in the fridge (solid like but membrane is liquid ordered state) NOT GOOD FOR BIOLOGICAL MEMBRANE
42
when is a biological membrane healthy
being in a balanced fluid state with mix of saturated and unsaturated fatty acids; maintained between Lo and Ld
43
describe a liquid disorder state (Ld)
complete fluid, not good
44
how does the concentration of unsaturated and saturated acids change the membrane fluidity?
the more saturated fatty acids will increase the order/ rigidity of the membrane while unsaturated will increase the fluidity.
45
describe uncatalyzed lateral diffusion
when a phospholipid goes from one area on its leaflet to another; very fast, dynamic
46
describe uncatalyzed transbilayer (flip flop) diffusion
when phospholipids switch leaflets; very slow, not favorable since it pulls a hydrophilic head through hydrophobic legs
47
describe catalyzed transbilyar translocations
using Flippase, Flooppase, or scamblase, phospholipids can change leaflets
48
flippase moves phospholipids...
from the outer leaflet to the inner leaflet; uses ATP
49
floppase moves phospholipids...
from the inside of the cell to the outside; uses ATP
50
scramblase moves phospholipids...
across the leaflet down a gradient and doesn't use ATP
51
describe cholesterol
maintains membrane fluidity by having hydrophilic and hydrophobic regions and broadening/buffering the temperature range the membrane can handle
52
describe simple diffusion
for small, non polar molecules (ex. O2 or NH3) based on concentration gradient
53
describe facilitated diffusion
going down a concentration gradient but requires a transport protein (ex. glucose transporters)
54
describe primary active transport
ex. flip flop; energy supplied to move something against concentration gradient; ATP hydrolysis occurs on transport
55
describe secondary active transport
moving a solute against its concentration by using energy from a secondary source such as an ion moving in on its own concentration gradient
56
describe ion channel
simple channels, similar to facilitated diffusion, highly specific for ions; gated mechanism; only move down concentration gradient
57
describe ionophore
small molecules that mask charge of ion and move it down a gradient
58
what is the relationship between Kt and affinity for a solute
the lower the Kt, the higher the affinity of a solute since the lower Kt means the less amount of time it took to reach V1/2max
59
where are GLUT1 transporters
ubiquitous
60
where are GLUT2 transporters
liver, pancreatic islets, intestine; where glucose gets stored as glycogen/ fat
61
where are GLUT3 transporters
brain and testis, highest affinity for glucose since brain does not use fatty acids for energy
62
where are GLUT 4 transporters
muscle, fat, heart *insulin dependent high glucose releases insulin which allow GLUT4 to be expressed; low glucose does not active GLUT4
63
what is uniport v cotransport? symport v antipode?
U: one molecule one way C: two molecules S: same way 2 molecules A: different ways 2 molecules
64
describe chloride bicarbonate (anion) exchanger
CO2 + H2O -> carbonic anhydrase -> HCO3- + H+ + Cl-(from outside * and produces reverse when moves down cell (via concentration gradient) and is in lungs use exchanger to facilitate the conversion of CO2-> HCO3- -> CO2 occurs in red blood cell anion (Cl-) comes in while HCO3- leaves or vice versa depending the area of the cell is in antiporter 80% CO2 is transferred like this
65
what is the equation for free energy change of transport
delta G = RT ln ( C2/C1) OR R = 8.314 J/molK T = temperature C1 = initial concentration on one side of membrane C2 = final concentration on other side of membrane dont worry about standard bc it would be zero if concentration 1 = C2
66
when is delta G favorable/ unfavorable in transport energy context
delta G is not favorable/ + when going against/ low to high delta G is favorable / negative when going with gradient (high to low)
67
what is the delta g equation for a charged species
+ ZF(delta psi) Z = charge of species F = 96,480 J/Vmol delta psi = membrane potential
68
sign of delta psi depends on...
which way movement is occuring in to out = (+) delta psi out to in = (-) delta psi
69
Describe the P-type ATPase
primary active transporters: type 3 transporter: E1 configuration without ATP; with ATP allows calcium to bind; 2 gated mechanism; reversibly phosphorylated by ATP at phosphorylation domain
70
Describe ABC Transporter
ATP Binding Cassette pump out of the cell hydrolyzing ATP causes conformational cell to push molecule out primary active transporter ex. flip flop used to get toxins out ubiquitous
71
Describer Na+ Glucose Symporter
secondary active transport; symport; moves glucose down Na+ gradient; need 2 Na per glucose to move it into the cell (glucose then uses GLUT2 to get into blood circulation); Na K ATPase bring Na into the cell, ATP used here to establish gradient
72
what are the 4 general types of signal transduction
1. G protein couple receptor 2. receptor enzyme (tyr kinase) 3. gated ion channel 4. nuclear receptor - gene level
73
what is the difference between contact dependent and contact independent signal transduction
contact dependent/ electrical synapses: need contact to pass; junction contact independent: paracrine/ endocrine/ autocrine/ synaptic - dont need touch, just send it across
74
describe the G protein coupled receptor (ex. beta adrenergic receptor)
1) cell receptor receives epinephrine binds 2) G protein, hombre causes GDP to be replaced with GTP and active protein causing a cascade of activated G proteins (amplification) 3) effector enzyme of ion channel (adenylyl cyclase forms cAMP which activates PKA to start cell response on epinephrine)
75
Describe the Na+ K+ ATPase
3 Na+ out, 2 K+ in, 1 ATP used maintains concentration of ions across membrane
76
what happens when ABC Transporters are overstressed?
causes a fail in chemotherapy treatment for cancer cells express MDR1 to spit out anti tumor drugs
77
describe ion channels
single gate mechanism; highly selective; gating mechanism either voltage gated or ligand gated
78
describe specificity in terms of characterization of signals
only signal molecule fits in its binding site
79
describe amplification in terms of characterization of signals
enzymes active other enzymes in a cascade
80
describe modularity in terms of characterization of signals
proteins have interchangeable parts (like legos) in order to bind to multiple different signals when they have multivalent affinities
81
describe desensitization in terms of characterization of signals
receptor activation triggers feedback circuit that shuts off receptor
82
describe integration in terms of characterization of signals
when two signals have opposite effects on the same factor, the response is the net change
83
describe localized response in terms of characterization of signals
local and brief response when enzyme destroys a message from its producer
84
describe the alpha beta and gamma subunits of G
alpha G is GTP binding domain and effector protein binding domain; G beta-gamma subunit holds the inactive alpha
85
describe phospholipase c
another G protein effector enzyme that uses IP3 or DAG to phosphorylate target molecule

BCH4024 (5 decks)

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