Chapter 11 Flashcards
what are the six classes of lipids and their definitions?
free fatty acids: a common fuel
triacylglycerols: storage for of fatty acid
wax esters: nonpolar lipids, waxes
phospholipids: membrane lipids
spingolipids: membrane lipids that contain long- chain amino alcohol
isoprenoids: contains isoprene units, terpenes and steriods
fatty acids are are chains of hydrogen-bearing carbon atoms that have a ______ at one end and a ___________ at the other end
carboxylic acid at one end
methly group at the other end
fatty acids can also be numbered from the methyl carbon atom, which is called the _________ carbon
omega (w) carbon
because fatty acids are ionized at physiological pH, they are usually referred to as their ______ form, rather than the unionized acid
carboxylate form
most naturally occuring fatty acids have an _______ number of carbons in an unbranched chain.
fatty acids that contain only single carbon-carbon bonds are ________
fatty acids that contain one or more double bonds are __________. this can be cis or trans
even number of carbons
saturated
unsaturated
why do unsaturated fatty acids have lower melting temperature than saturated fatty acids?
unsaturated fatty acids are often found in cis configuration, in which double bonds are present. This creates a kink in the molecule not allow for it to stack has tightly or as efficiently. thus the intermolecular interaction between the molecules are weaker allowing it to have lower melting temperature. It should be noted that saturated fatty acids stack tighter and they have a higher melting temperature, due from the higher intermolecular interactions
cis polyunsaturated fatty acids are essential components of our diets because we ____________
cannot synthesize them
these fatty acids are precursors to a variety of hormones and appear to offer some protection from coronary heart disease
what are 3 omega 3 fatty acids
EPA
DHA
ALA
what are 3 non essential fatty acids (ones we make ourselves)
omega 5, omega 7, omega 9
what are important chemical reactions of fatty acids?
- esterification
- hydrogenation
- oxidation
- protein acylation
what are eicosanoids?
they are signaling molecules made by oxidation of 20 carbon fatty acids
give example of three eicosanoids?
prostaglandin, thromboxane, leukotriene
what is the storage form of fatty acids?
triacylglyerols
define triacylglycerols?
also what type of fat are they and why?
triacylglycerols are esters of glycerol with three fatty acids
neutral fats because they have no charge
they contain fatty acids of varying length and can be a mixture of saturated and unsaturated
why are triglycerols better for storage than glucose??
- Hydrophobic and coalesce into droplets; store an equivalent amount of energy in about one-eighth the space
- More reduced and thus can release more electrons per molecule when oxidized
wax esters define and what are they composed of?
they are complete mixture of nonpolar lipids
they provide a protective coating on leaves, fruits, and skin.
wax esters are composed of long-chain fatty acids and long-chain alcohols are prominent constituents of most waxes
what are the common types of membrane lipids?
phospholipids
glycolipids
cholesterol
phospholipids are __________ with a ______ head (phosphate and other polar or charged groups) and hydrophobic fatty acids
act in membrane formation, emulsification, and as surfactant, spontaneously rearranged into ordered structure when suspended in water
amphipathic with a polar head group
what are some general features of phospholipid?
small molecules
amphipathic
spontaneously form vesicles, micelles, and bilayers in aqueous solution
what are the two types of phospholipids?
- sphingomyelin= contain sphingosine instead of glyerol (also classified as spingolipids)
- phosphoglycerides- contain a glycerol, fatty acids, phosphates, and an alcohol.
- -simplest phosphoglyceride is phosphatidic acid composed of glycerol-3-phosphate and two fatty acids
- -phosphatidylcholine (lecithin) is an example of alcohol esterified to the phosphate group as choline
what phsphoglyceride is important with GPI anchors. And what are GPI anchors?
glycosyl phosphatidylinositol
GPI anchors= attach certain proteins to the membrane surface. proteins are attached via and amide linkage
proteins acylation makes what type of proteins?
prenylated proteins
what do phospholipases do?
they hydrolyze ester bonds in glycerophospholipid molecules.
They have three major functions: membrane remodeling, signal transduction, and digestion
In relation to phospholipases
- membrane remodeling=?
- signal transduction=?
- Digestion=?
toxic phospholipases-
through use of phospholipases,
- membrane remodeling involves the removal of fatty acids to adjust the ratio of saturated to unsaturated or repair a damaged fatty acid
- signal transduction- phospholipid hydrolysis initiates the singal transduction by numerous hormones
- digestion- pancreatic phospholipases degrade dietary phospholipids in the small intestine
toxic phospholipases- various organisms use membrane-degrading phospholipases as means of inflicting damage. bacterial a-toxin and necrosis from snake venom
what are the functions of sphingolipids?
Important components of animal and plant membranes
sphingosine (long chain amino alcohol) and ceramide in animal cells
_________ is found in most cell membrane but is most abundant in the myelin sheath of nerve cells
sphingomyelin
Sphingolpid: ceramide
cermaides are also precursors of ____________.
and what are these?
glycolipids
A monosaccharide, disacchaaride, or oligosaccharide attached to a ceramide through an O-glycosidic bond
Most important classes are cerebrosides, sulfatides, and gangliosides (may bind bacteria and their toxins)
lipid classes:
cerebrosides:
galactocerebroside:
sulfatides:
gangliosides:
cerebrosides= have a monosaccharide for their head group
galactocerebrosides are found in brain cell membranes
sulfaides are negatively charged at physiological pH
gangliosides possess oligosaccharide groups; occur in most animal tissue and Gm2 is involved in
tay-Sachs disease
several lysosomal storage diseases involve sphingolipid metabolism or ________
sphingolipidoses
Isoprenoids:
- terpenes:
- Steroids:
Terpenes- essential oils of plants
steroids- derivatives of hydrocarbon ring of cholesterol
give an example of sex hormone. and define
progesterone, testosterone, estradiol
these are molecules that regulate the development of primary and secondary sex characteristics and various reproductive behaviors
give an example of a mineralocorticoid? and define
aldosterone
regulates plasma concentration of several ions, especially sodium
give an example of an glucocortiocoid? and define
cortisol. it regulate the metabolism of carbs, fats, and proteins
give an example of an bile acid? and define
cholic acid
it is converted into bile salts, aid the absorption of dietary fats and fat-soluble vitamins in the intestine
define lipoproteins?
any protein covalently attached to lipid group
plasma- transport of lipid molecules
apoproteins synthesized in liver/ intestine
what are the five classes of apolipoproteins?
There are different types of lipoproteins with different ratios of lipid and protein components
A, B, C,D,E
a membrane is a noncovalent heteropolymer of a __________ and associated proteins (__________)
lipid bilayer
fluid mosaic model
Membrane structure?
proportions of lipid, protein, and carbohydrate vary considerably amond cel ltypes and organelles
proteins are sometimes covalently bound to ______ to localize the protein to the cell membrane
lipids
______________: phospholipids form biomolecular layers at relatively low concentrations; this is the basis of membrane structure
membrane lipids
____________________ refers to the viscosity of the lipid bilayer
membrane fluidity
The movements of molecules from one side of a membrane to the other requires a _________
flipase
Membrane fluidity largely depends on the percentage of unsaturated fatty acids and cholesterol
Cholesterol contributes to stability with its rigid ring system and fluidity with its flexible hydrocarbon tail
biological membrane features:
- highly selective permeability barriers
- amphiphillic organization
- self-sealing
- asymmetry
- fluid mosaic model: liquid and asymmetric
- fluidity and thickness of membrane are determined by their lipid composition
saturated, longer chains=less fluid
- hydrophoic core
- hydrophillic surface
___________________ is provided by the hydrophobic chains of the lipid bilayer, which is impermeable to most all molecules (except small nonpolar molecules)
Membrane proteins help regulate the movement of ionic and polar substances
Small nonpolar substances may diffuse down their concentration gradient
selective permeability
Different functions=different protein compositions
Pure lipid: insulation (neuronal cells) Other membranes: on average 50% Energy transduction membranes (75%) -Internal membranes of mitochondria and chloroplast -Purple membrane of halobacteria
membrane protiens
25-35% of genome
>17,000 structures of water soluble proteins
~150 unique structure of membrane proteins
-Many functions that are important therapeutic targets
- Receptors
- Transporters
- Ion channels
membrane proteins
integral-membrane spanning-interaction with HC of bilaer
peripheral-do not penetrate HC; mainly electrostatic interaction with one hydrophillic surface of bilayer
structural features of membrane proteins
how are they similar to soluble proteins
what are the difference to soluble proteins
similar?
interior is nonpolar, they are tightly packed, H-bonded alpha helices and b sheets, hydrophobicity of interiors of membrane proteins are the same
differences?
outer surfaces are more hydrophobic, lengths of secondary structures are greater
directionality defined by membrane orientation-positive inside rule
membrane and microdomains
lipids and proteins in membranes are not uniformly distributed
specialized microdomains like “lipid rafts” can be found in the external leaflet of the plasma membrane
lipid rafts
include what? and describe
include cholesterol, spingolipids, and certain proteins.
lipid molecules are more ordered (less fluid) than non-raft regions
lipid rafts have been implicated in a number of processes: exocytosis, endocytosis, and signal transdution
what is the importance of asymmetry?
all membrane proteins function in a directed way
correct insertion in the membrane is essential for their biologic function
what are two transport processes?
active:
- requires energy
- pump against concentration gradient
passive:
- with gradient
- diffuse/osmosis
- equilibrium
______ transport has two forms: primary and secondary
active transport
in _______ active transport, transmembrane ATP-hydrolyzing enzymes provide the energy to drive the transport of ions or molecules, Na,K, ATPase (primary active transport)
in _______ active transport, transmembrane ATP-hydrolyzing enzymes provide the energy to drive the transport of ions or molecules, Na,K, ATPase (primary active transport)
primary active transport
in ____________ transport, concentration gradients formed by primary active transport are used to move other substance across the membrane
-NaK ATPase pum in kidney drives the movement of D-glucose against its concentration gradient
secondary active transport
cardiotonic steriods, such as ________ strengthen heart contranctions and are used to treat heart disease.
by inhibiting the Na^+, ATPase,Ca^+2 ion remains in the cell longer leading to more robust heart contractions
__________ isolated from the efoxglove plant digitalis purpurea
digoxin
digoxin
mutations in what gene leads to cystic fibrosis?
CFTR
impaired membrane transport mechanisms can have very serious consequences. Cystic fibrosis, is a fatal autosomal recessive genetic disorder, is one of the best understood examples. the disorder is caused by a ________________
__________ a missing or defective cystic fibrosis transmembrane conductance regualtor (CFTR)
give an example of an alosteric regulated channel
GABA gates Cl^-
what is a combined voltage and ligand gating NMDA channelal?
glutamate
charge repulsion amoung the four ion binding sites in the potassium channel accounts for the reapid transport of K ions ______ their concentration gradient
down
