Chapter 9: Lipids and Biological Membranes Flashcards
Fats, oils, certain vitamins and hormones, and most nonprotein membrane components are
lipids
Lipid molecules in the form of what are essential components of biological
membranes.
lipid bilayers
Lipids containing hydrocarbon chains serve as what
energy stores
Over half of the fatty acid residues of
plant and animal lipids are
unsaturated and polyunsaturated
Bacterial fatty acids are rarely
polyunsaturated
Fatty acid double bonds almost always have the what configuration
cis
melting points to what
with the degree of unsaturation
decrease
function as energy reservoirs in animals and are therefore their most abundant class of lipids even though they are not components of cellular membranes.
Triacylglycerols
do written notes for slide 5
are complex mixtures of triacylglycerols whose fatty acid compositions vary with the organism that produced them
Fats and oils
are the major lipid components of biological membranes.
Glycerophospholipids
Glycerophospholipids have what heads and what tail
nonpolar aliphatic (hydrocarbon)“tails” and polar phosphoryl-X“heads.”
which can disrupt cell
membranes cell thereby losing cells
phospholipase A2
are glycerophospholipids in which the C1 substituent of the glycerol moiety is linked via an α,β-unsaturated ether linkage rather than through an ester linkage
Plasmalogens
The N-acyl fatty acid derivatives of sphingosine are known
as
ceramides
The most common sphingolipids are
sphingomyelins
(also sphingophospholipids)
is the major lipid of lung surfactant which prevents the collapse of the alveolar space.
Dipalmitoylphosphatidylcholine (DPPC)
are ceramides with head groups that consist of a single sugar residue.
Cerebrosides
are the most complex
glycosphingolipids.
Gangliosides
are primarily components of cell-surface membranes
and constitute a significant fraction (6%) of brain
lipids
Gangliosides
Their complex carbohydrate head groups, which extend
beyond the surfaces of cell membranes, act as
specific receptors for certain pituitary glycoprotein hormones.
Gangliosides
Disorder of ganglioside
breakdown is responsible for hereditary
fatal neurological deterioration in early childhood.
Tay-Sachs disease
which is the most abundant steroid in animals
cholesterol
is a major component of animal plasma membranes and its fused ring system provides it with greater rigidity than other lipids.
cholesterol
is the metabolic precursor of steroid hormones in mammals.
Cholesterol
affects carbohydrate, protein, and lipid metabolism.
Cortisol
regulate the excretion of salt
and water by the kidneys.
Aldosterone
Impaired adrenocortical function
Addison’s disease
decreased amounts of
glucose in the blood)
hypoglycemia
Conversely, adrenocortical hyperfunction, which is
often caused by a tumor of the adrenal cortex, results in
Cushing’s syndrome
increased amount of
glucose in the blood)
hyperglycemia
is male sex hormone,
Testosterone
is female sex hormone
estrogen
is nonenzymatically formed in the skin of animals through the
photolytic action of UV light
Vitamin D
is a lipid synthesized by plants
Vitamin K
Vitamin K in plants
phylloquinone
Vitamin K in bacterica
menaquinone
is a highly hydrophobic molecule which is incorporated into cell membranes, where it functions as an antioxidant that prevents oxidative damage to membrane proteins and lipids.
Vitamin E
is derived mainly from plant products such as β-carotene
Vitamin A or retinol
act at very low concentrations and are involved in the production of pain and fever,
and in the regulation of blood pressure, blood coagulation, and reproduction.
Eicosanoids
In aqueous solutions, amphiphilic molecules such as soaps and detergents (single-
tailed lipids) aggregate forming what
micelles
In aqueous solutions, phospholipids (glycerophospholipids or sphingomyelins) can form
liposomes which are self-sealing solvent-filled vesicles made of only a single bilayer.
Lipid Bilayers
catalyze chemical reactions, mediate the flow of nutrients and wastes across the membrane, and participate in relaying information about the extracellular environment to various intracellular components.
Membrane proteins
associate tightly with membranes through hydrophobic effects and can be separated from membranes only by treatment with agents that disrupt membranes.
Integral or intrinsic proteins
which are channel-forming proteins in the outer membrane of gram-negative bacteria
porins
permit the entry of small polar solutes such as nutrients
porins
can be dissociated from
membranes by relatively mild procedures that leave the membrane intact, such as exposure to high ionic strength salt solutions or pH changes
Peripheral or extrinsic proteins
Lipid-linked proteins come in three varieties called what
prenylated proteins
fatty acylated proteins
glycosylphosphatidylinositol-linked proteins
is defined by the fluid mosaic model. A key element of the model is that integral proteins can diffuse laterally in the lipid matrix
membrane structure
facilitate the fusion of membranes by bringing them together
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