test 2 Flashcards
(104 cards)
1
Q
define lipid
A
water insoluble biomolecules that are highly soluble in organic solvents
2
Q
what are the hydrophobic properties of lipids due to
A
fatty acids
3
Q
what are some examples of derivatives of fatty acids
A
hormones
signal molecules
intracellular messengers
4
Q
what is the range of C atoms in fatty acids
A
14-24 (even numbers)
5
Q
what are the most common numbers of carbon for fatty acids
A
16 and 18
6
Q
what configuration of double bonds is most common in unsaturated fatty acids
A
cis
7
Q
what determines the properties of fatty acids
A
length of the chain and degree of saturation
8
Q
what occurs to the melting points of saturated fatty acids as the chain length increases
A
melting point increases
9
Q
do unsaturated or saturated fatty acids of same length of lower melting point
A
unsaturated
10
Q
what fatty acids fall into NEFA
A
laurate, myristate, palmitate, stearate, arachidate, behenate, lignocerate, palmitoleate, oleate
11
Q
what fatty acids are w-6 EFA
A
linoleate
arachidonate
12
Q
what fatty acids are w-3 EFA
A
linoleate
13
Q
what are the major membrane components of lipids
A
phospholipids
glycolipids
cholesterol
14
Q
what are the 4 components of phospholipids
A
fatty acid
backbone to which fatty acids are attached
phosphate
alcohol attached to phosphate
15
Q
what is phosphatidylserine important for
A
memory and cognition
16
Q
what is phosphatidylcholine important for
A
major constituent of cell membrane and pulmonary surfactant
17
Q
what is phosphatidylethanolamine important for
A
composing 25% of all phospholipids
found particularly in nervous tissue (white matter of brain)
18
Q
what is phosphatidylinositol important for
A
signalling and other functional activities in eukaryotic cell
19
Q
what is diphosphatidylglycerol important for
A
important component of inner mitochondrial membrane
20
Q
define sphingosine
A
amino alcohol that contains a long, unsaturated hydrocarbon chain
21
Q
how is the amino group of the sphingosine backbone linked to a fatty acid
A
amide bond
22
Q
what are glycolipids derived form
A
sphingosine
23
Q
what is the difference between sphingomyelin and glycolipids
A
identify of the unit that is linked to the primary hydroxyl group of the sphingosine backbone
24
Q
how is the sugar residue oriented in glycolipids
A
on the extracellular side of the membrane
25
what is cerebroside
simples glycolipid
contains a sugar residue (glucose or galactose)
important component in animal muscle and nerve cell membrane
26
what is cholesterol built from
4 fused saturated hydrocarbon rings
27
what is the metabolic precursor of steroid hormones
cholesterol
28
what are common features of biological membranes
```
sheetlike structure
mainly consists of lipids and proteins
hydrophilic and hydrophobic unit
specific proteins are embedded in lipid bilayers and mediate distinct functions
form non-covalent assemblies
asymmetric
fluid structure (both lipid and protein diffuse rapidly in the plane of the membrane but do not rotate across the membrane)
electrically polarized (inside negative)
```
29
what are characteristics of micelle
limited structure
usually less than 20 nm
formed when a variety of molecules including soaps and detergents are added to water
30
why are phospholipids and related molecules important membrane consituents
they readily form extensive bilayers
31
what type of process is the formation of lipid bilayers
self-assembly
32
what are the major driving forces for lipid bilayer assembly
```
hydrophobic interaction (major)
van der waals (attractive forces between hydrocarbon tails)
electrostatic and hydrogen-bonding: attractions between polar head groups and water molecules
```
33
what are the 3 significant consequences of the hydrophobic interactions of the lipid bilayer
lipid bilayers have inherent tendency to be extensive, close on themselves so that there are no edges with exposed hydrocarbon chains (form compartment), and are self-sealig
34
how are peripheral membrane proteins primary bound to membranes
electrostatic and hydrogen bond interactions with the head group of lipids
35
how are peripheral membrane proteins dissociated
adding salt or pH changes
36
where are peripheral membrane proteins bound to the surfaces of integral proteins
cytosolic or extracellular side of membrane
| anchored to the lipid bilayer by a covalently attached hydrophobic chain (i.e.: fatty acid)
37
what is the most common structure motif in membrane proteins
membrane-spanning alpha helices
38
what are the kinds of modification in lipid-linked proteins
palmitoylation of cysteine residues by a thirster bond
fernesylation of cysteine residues at the C-terminus
Glycosylphosphatidylinositol-link to the carboxyl terminus
39
what are the functions of farnesylation of the C-terminus
anchoring the protein to the membrane and facilitating the protein-protein interaction
40
what does glycosyl phosphatidylinositol (GPI) do
anchors the proteins to the outer leaflet of the plasma membrane
41
what is the site of most TCA cycle and fatty acid oxidation
mitochondrial matrix
42
what Is membrane fluidity controlled by
fatty acid composition
| cholesterol content
43
what are major contributors to fatty acid composition
```
length of fatty acid chain
saturation levels (Tm, rigidity)
position of double bands, (cis position produces bend), effects Tm, provides more fluidity
```
44
what type of environment does membrane fluidity provide
environment where signal transduction and molecule transportation takes place
45
how do lipid and many membrane proteins move
laterally (lateral diffusion)
46
what does FRAP do
tests the dynamics of membrane molecules
47
what does the rate of recovery of fluorescence depend on (FRAP)
lateral mobility of the fluorescent labeled components
48
what are the main components of plasma membranes
carbs
glycoproteins
glycolipids
49
where does glycosylation occur
extracellular surface of the plasma membrane
50
what does glycocalyx participate in
cell adhesion, lymphocyte homing, and many others
51
how do antibodies recognize blood cell types
extracellular carbohydrates
52
define nuclear pores
located in the nuclear envelope; closed membranes that come together
53
why must membranes be able to separate and join together
so that cells and compartments can take up, transport, and release molecules
54
what does SNARE do
it is a protein that gathers the appropriate membranes to initiate fusion process
55
what is an analogy to describe fission
it is like pinching a balloon (making 2 balloons from one)
56
what is mitochondrial fission particularly used for
mitochondrial proliferation
57
why is fission harder in mitochondria than many sign payer organisms
because the inner membrane will be very hard to divide (must get electron transport chain component as well) even though the outer will not be that difficult
58
explain why mitochondria fusion is a salvage process
when a mitochondria is sick,healthy ones will try to fuse with the unhealthy to make them healthy. if they are beyond repair, mitophagic mitochondria will break down sick mitochondria and re-used usable components (recycle)
59
what are requirements for inner membrane fusion in mitochondria
sufficiently large electrochemical gradient
| elevated GTP levels must be available for hydrolysis
60
what are the vast majority of mitochondrial proteins encoded by
the nuclear genome
61
what does Tim do in mitochondria
it mediates transport across the inner mitochondrial membrane
62
what is HSP 70 crucial for
driving polypeptide translocation
63
what is considered the matrix targeting signal
N-terminal signal
64
what must be true for a protein to be imported into the mitochondria
it must first be unfolded and it is refolded once the protein enters inside
65
what do membrane transport proteins facilitate
the movement of specific molecules across the PM
66
what is the plasma membrane very permeable to
lipophilic molecules
67
what determines the ionic composition of the cell (membrane transporters)
activity and protein levels of specific transporters
68
what governs the biochemical/metabolic characteristics of a cell
expression of specific transporters
69
what type of bond does the transporter form in P type ATPases
covalent bond with the phosphate to form an enzyme-phosphate intermediate
70
where does phosphorylation occur in P type ATPases
conserved asparate residue
71
what is a potential inhibitor of the Na pump
plant steroids
72
what does the PMCA do
transports calcium from cytosol to extracellular side
73
what stimulates PMCA
calcium binding protein calmodulin (CaM)
74
what does SERCA do
transports calcium from cytosol to ER
75
what is the mechanism of action of ABC transporters
1. protein free of substrate and ATP
2. channels face intracellular side
3, substrate binds
4. conformational changes in ATP binding cassettes
5. increase affinity for ATP
6. ATP binds
7. conformational change in ATP binding cassette
8. reorientation of the membrane spanning domains
9. expulsion of substrate to extracellular side
10. ATP hydrolysis resets transporter to original state
76
what is lactose permease
symporter
uses proton gradient generation by oxidation of fuel molecules to drive lactose and other sugars against concentration gradient
77
what do ion channels mediate
facilitated passive transport
78
what are the 3 types of ion channels and describe them
voltage-gated: respond to change in membrane potential
chemically gated; respond to ligands such as neurotransmitters
mechanically gated: respond to mechanical stimuli, found in sensory neurons
79
what is the model of voltage gated (how is it set up)
sensors include segments S1-S4
| pore is S5 and S6
80
explain the ball and chain model
when the port is closed, the domain is free flowing. as it opens, the peptide gets pulled toward the base of the pore causing the pore to close (blocks the pore)
*this causes the inactivation of voltage-gated ion channels
81
where is AcH located
post-synaptic side
82
what is the structure of the Ach receptor
pentamer of 4 kinds of membrane spanning subunits (2 alpha, 1, beta, 1 game, 1 delta) arranged in the form of a ring that creates a pore through the membrane
83
what is the most important manifestation of membrane transport
basis for communication in the nervous system
84
what is a nerve impulse
electrical signal produced by the flow of current across the plasma membrane of a neuron
85
what are the steps of an action potential
1. AP arises form large transient changes in the permeability of the axonal membrane to ions
2. conductance for Na+ changes first due to opening of sodium channels
3. depolarization increases permeability to Na+ which begin to flow in via the Na+ channel due to high concentration outside
4. depolarization then opens the K+ channels and K+ moves out
86
what are the steps of synaptic transmission
1. AP reaches presynaptic terminal
2. depolarization opens up the VGCC
3. calcium enters cell
4. causes fusion of synaptic vesicles
5. exocytosis: release of NT in synaptic cleft
6. NT bind to its receptor on post-synaptic side
7. opens up a ligand-gated channel
87
how are gap junctions packed
hexagonal array
88
what kind of molecules can pass through gap junctions
small hydrophilic molecules and ions can pass through these channels
89
what is the structure of a gap junction
each channel made of 12 connexin
six connexin molecules arrange hexagonally to form a half channel called connexon
2 connexon join end to end in the intracellular space to form a functional channel
90
what do gap junctions ensure in cardiac tissue
synchronous response to stimuli
91
how are gap junctions sealed and why
sealed by high Ca++ and H+ to protect normal cells from injured or dying cells
92
how are gap junctions regulated
by membrane potential and hormone-induced phosphorylation
93
what do gap junctions connect
cytoplasm to cytoplasm
94
what are characteristics of aquaporins
increase rate of water flow across membranes
found in RBC, kidney, cornea
have 6 transmembrane alpha helical domains
95
what are the steps of solid phase peptide synthesis
1. anchoring of the C terminus aa to a solid resin
2. deprotection of the amino terminus
3. coupling of the free amino terminus with the DCC-activated carboxyl group of the next aa (2 and 3 repeated for each added aa)
4. completed peptide is released from the resin
96
how are fatty acids stored as fuel molecules
triacylglycerols
97
how can the dynamics of mitochondria effect neurodegenerative diseases
both inefficient mitochondrial fission and fusion could contribute to progression of neurodegenerative dieseas
98
what occurs if something goes about the Tm
it transitions from the rigid state to the fluid state
99
what state does the presence of saturation in fatty acids favor
rigid state because their straight hydrocarbon chains interact very favorably with one another
100
what occurs with a cis double bond in fatty acids
a bend occurs, which interferes with highly ordered packing of fatty acid chains and Tm is lowered
101
how do bacteria regulate fluidity of their membranes
by varying the number of double bonds and the length of their fatty acid chains
102
what is the key regulator of membrane fluidity in animals
cholesterol
103
what are the 2 main roles of the lipid bilayer
solvent for integral membranes and permeability barrier
104
what are the main components of the outer and inner leaflets of the lipid bilayer:
outer: sphingomyelin and phosphatidylcholine
inner: phosphatidylethanolamine and phosphatidylserine
both: cholesterol
