Exam 1: M5 Flashcards
(88 cards)
1
Q
Function of lipids
A
- components of membranes
- energy storage
3.signaling events
2
Q
properties of lipids
A
- not true polymers (don’t have regularly repeating monomers)
- Soluble in organic solvents and detergents
- mostly amphipathic
- lots of diff structures
3
Q
4 lipid classes are
A
- Triacylglycerols
- (Glycero)phospholipids
- Sphingolipids
- Steroids/sterols
4
Q
Most lipids contain
A
FA
5
Q
FA contain carboxylic acid followed by long _____
A
hydrocarbon chains
6
Q
a hydrocarbon tail is ____ carbon atoms long
A
14-20
7
Q
Most common hydrocarbon chains
A
C16 and C18
8
Q
FA can be ____ or ____
A
saturated or unsaturated
9
Q
are unsaturated FA cis or trans bonds
A
cis, always!
10
Q
physical properties affected by composition
A
mp, rigidity, length of tail, degree of sat
11
Q
Examples of FA
A
stearic acid, oleic acid, linoleic acid, a-linolenic acid
12
Q
mp inc w ___ mass
A
inc
13
Q
mp dec w ___ degree of saturation
A
dec
14
Q
fluidity inc w ____ degree of saturation
A
dec
15
Q
where are triacylglycerols
A
adipose tissue in lipid droplets
16
Q
function of triacylglycerols
A
storage fat in animal tissues
17
Q
do triacylglycerides store more energy than carbs? why or why not
A
yes, they’re fully reduced and not hydrated
18
Q
triacylglycerols are based on ___
A
glycerol
19
Q
triacylglycerols are ___ and ____
A
nonpolar and hydrophobic
20
Q
3 hydroxyl groups on glycerol connected to FA are connected by ____ linkages
A
ester
21
Q
Are triacylglycerides amphipathic
A
no
22
Q
are triacylglycerides in mems
A
no
23
Q
glycerophospholipids are important components of
A
mems in lipid bilayers
24
Q
glycerophospholipids are based on
A
glycerol-3-phosphate
25
glycerophospholipids: ester linkages to FA at positions
C1 and C2
26
X is often a ___ head group on glycerophosolipid
polar
27
glycerophospholipids are ___
amphipathic
28
phospholipids are important in
mems
29
common classes of glycerophospholipids (name of X-OH)
water
ethanolamine
choline
serine
myo-inosital
30
common classes of glycerophospholipids (formula of -X)
-H
-CH2CH2NH3+
-CH2CH2N(CH3)3+
-CH2CH(NH3+)COO-
sugar ring
31
common classes of glycerophospholipids (name of phospholipid)
phosphatidic acid
phosphatidylethanolamine
phosphatidylcholine
phosphatidylserine
phosphatidylinositol
32
what type of linkage links X polar head group to O on phosphate for glycerophosphate
phosphodiester
33
what are sphingolipids based on
alcohol sphingosine
34
are sphingolipids important in mem
yes, esp in nervous system
35
what is a ceramide
parent group of all sphingolipids; a sphingosine with FA linked to amino group
36
what type of linkage is a FA residue linked to glycerol-like portion of ceramide
amide
37
most common sphingolipid
sphingomyelin
38
structure of sphingomyelin
ceramide + phosphocholine OR phosphoethanolamine head group linked to OH
39
what defines a sphingomyelin
phosphocholine or phosphoethanolamine linked to ceramide w/ palmitate reside linked through amide bond
40
where are spingomyelins important
pm
41
other sphingolipids are formed from ceramides and ___. these are called glycolipids
sugars
42
structure of glycolipid
C3 alcohol/phosphate is replaced by sugar moiety
43
cerebroside
ceramide _ 1 sugar residue (glucose, galactose)
no phosphate group, nonionic but still polar bc of sugar
44
most complex sphingolipids
gangliosides
45
ganglioside
ceramide + complex carbohydrate head groups
important in brain lipids
complex arrangement of sugar attached to one another linked off of this ceramide
receptors for toxin cholera
46
steroids and sterols are built around molecule w/ 4 ___
fused rings and is planar
47
sterol defined by -OH group at
C3
48
sterols are weakly
amphipathic bc of rigid rings
49
many other lipids are built around a 5C skeleton called
isoprenoids
50
simplest aggregate
micelle
51
micelles have a ____ membrane
single
52
formation of micelles or bilayers is driven by
hydrophobic effect
53
fluid like properties of bilayer membrane
lateral diffusions are common, transverse diffusion rare
constant mvmt
transition temp--> presence of cholesterol effects
54
macromolecules have an ____ w/in the mem
orientation
55
Phosphatidylinosital is an important
mem phospholipid
56
PIs are modified at specific positions by additional
phosphate groups
57
diff mems have diff ____
PI combinations
58
the 2 leaflets have diff
compositions
59
what achieves diff compositions of 2 sides of mem
flippases and translocases
60
protein functions
1. catalyze rxns (enzymes)
2. transport molecule (channels. pores)
3. Traffic molecules (coat proteins)
4. relay signals (G proteins)
61
what is key for identifying a mem
protein composition
62
types of mem proteins
integral, peripheral, lipid-linked
63
integral mems are ____ associated w bilayer
tightly
64
integral membs are ____ but still amphipathic
hydrophobic
65
structures that are transmembranic
alpha helices, beta barrels
66
need minimim of ___ A to span 30 A bilayer
28
67
to dec polar nature of backbone, ensure its fully
H bonded
68
which structures have fully H bonded backbones
alpha helix or beta sheets
69
hydropathy plots are useful for predicting
transmembrane helices
70
in hydropathy plot, + means
hphobic aa
71
in hydropathy plot, - means
hphilic aa
72
What to look for on hydropathy plot
at least 20 aa that are hphobic
73
peripheral mems are ___ associated w bilayer
loosely
74
peripheral mem proteins can be dissociated from mem by
extreme pH or high salt
75
peripheral mems bind to
specific lipids or to integral proteins
76
peripheral mems are stabilized by electrostatic interactions and
H bonding
77
lipid-linked proteins are
covalently attached to lipid and brings along protein of interest
78
what are the diff ways to covalently link FA to protein of interest
prenylation, FA linkaged, GPI anhored
79
prenylation
protein covalently attached to lipid
lipids are derived from isoprenoids
80
2 diff isoprenoids
farnesyl residue and geranylgeranyl residue
81
what do u get w prenylation
C-X-X-Y
82
what happens during prenylation
one of the isoprenoids link up covalently to protein of interest at cysteine residue--> thioether linkage
83
FA linkage: myristoylation
amide linkage to N terminal Gly
84
FA linkage: palmitoylation
thioester linkage to Cys residue
85
GPI anchored
-exists on exterior face of PM and really complicated linkage
-outer face of PM
86
how does GPI anchor work
get phosphoinositol moeity linked to protein of interest via ethanolamine group and a core tetrasaccharide added co-tslnally in rough ER
-get protein covalently linked through lipid of interest via complex bridge w/ ethanolamine group and tetrasaccharide
87
function of membranes
1. structure and support
ex. myelination around atoms
2. separate cellular processes
ex. gene expression and energy production
3. sequester dangerous chemical rxns
ex. breakdown of materials in lysosome
4. provide platform or staging area for cellular processes
88
why must membranes be connected
cells must move lipid and transmembrane protein and lipid cargo btwn compartments
