Lipid Structure and Function Flashcards
Amphipatic Molecule
molecule with both hydrophobic and hydrophillic regions
ie. lipids
When placed in aqueous solutions, lipids form structures that all the ______ regions to group internally while the _______ regions interact with water.
hydrophobic
hydrophillic
Phospholipids
phosphate and a alcohol containing a polar head group and hydrophobic fatty acid tail connected via phosphodiester linkage
clasified according to backbone of the molecule
Glycerol
three carbon alcohol that forms:
phosphoglycerides
glycerophospholipids
NOT all sphingolipids are ________
phospholipids
______ and _____ determine how an overall molecule will behave.
Saturation and Length
Fully Saturated Fatty Acid
only single bonds, no pi bonds (double bonds)
have greater van der Waals Forces and stable overall structure meaning they are solids at room temp (think butter)
Unsaturated Fatty Acid
includes one or more double bonds which intrudce kinks making it hard to stack/solidify making them liquids at room temp (oils)
Phospholipids with _____ fatty acids are more fluid regions of the phospholipid bilayer.
unsaturated
Glycerophospholipids/Phosphoglycerides
phospholipids with a glycerol backbone bonded to two fatty acids via ESTER linkage and phosphodiester linkage to a polar head group
named according to head group (can be + neutral or - charged)
within each subtype, FA chain length and saturation can vary
Phosphatidylcholine
phosphoglyceride with a choline head group
Phosphatidylethanolamine
phosphoglyceride with a ethanolamine head group
Sphingolipids
ABO blood typing determined by cell surface antigens which are sphingolipids
sphingosine backbone with long chain non polar fatty acid tails and polar head groups
can be phospholipid if they contain a phosphodiester bond
others have glycosidic linkages to sugar instead of phosphodiester linkages
4 Classes:
- Ceramide
- Sphingomyelins
- Glycolipids
- Gangliosides
Glycolipid
any lipid linked to a sugar via glycosidic linkage
Ceramide
simplest sphingolipid
single H as its head group
Sphingomyelins
major class of sphingolipids that are also phospholipids
either have phosphatidylcholine or phosphatidylethanolamine as head groups meaning they have a phosphodiester bond
no net charge head groups
major component of cell membrane for cells producing myelin (Schawn and Oligodendrocytes)
Glycosphingolipids/Glycolipids
have head groups composed of sugars bonded by glycosidic linkages ; no net charge
no phosphodiester linkage so they aren;t phospholipids
on outer surface of the plasma membrane and can be further classified as cerebrosides or globosides
Cerebrosides
glycolipids with single sugar
Globosides
glycolipids with two or more sugars
Gangliosides
most complex sphingolipids
polar head groups made of oligosaccahrides with one or more N-acetylneuraminic acid (sialic acid) molecules at terminus and a negative charge
considered glycolipids with glycosidic linkages
cell interaction, recognition and signal transduction
Waxes
esters of long chain fatty acids with long chain alcohols
solids at room temp
protection for animals (prevent dehydration/lubrication) and plants (also help with excessive evap)
Lipids serve the following roles:
structure, cellular signaling, coenzymes and energy storage
Terpenes
metabolic precursors to steroids and other lipid signaling molecules
built from isoprene (C5H8) moieties with structural pattern of carbons grouped in multiples of 5
scented for protection for insects/plants
Monoterpenes
two isoprene units, abundant in oils and terpentine
Sesquiterpenes
three isoprene units
Diterpenes
four isoprene units where Vitamin A is one of them
Triterpenes
six isoprene units -> becomes various steroids and cholesterols
Tetraterpenes
8 isoprene units -> B carotene and lutein (Carotenids)
Terpenoids/Isoprenoids
derivatives of terpenes that have undergone oxygenation/rearrangement of carbon skeleton
modified by functional groups
precursor molecule like Terpenes to feed into pathways to produce steroids and influence biological function
Steroids
metabolic derivatives of terpenes with the following structure:
4 cycloalkane rings fused together: 3 cyclohexanes and one cyclopentane
functionality is determined by the oxidation status of these rings and functional groups
nonpolar due to large number of carbons and hydrogens
Steroid Hormones
steroids that act as hormones that are secreted by endocrine glands and travel on protein carriers to bind to receptors
biological signals capable of regulating metabolism and gene expression
Cholesterol
steroid
component of phospholipid bilayer that mediates membrane fluidity
amphipathic molecule that has constant fluidity in the membrane
Low temps: keeps membrane from solidifying
High Temps: keeps membrane from being too permeable
precursor to many molecules
Prostaglandins
20 carbon unsaturated carboxylic acids from arachidonic acid and contain a five carbon ring
paracrine/autocrine signaling molecule
regulate cAMP synthesis which impacts other hormone actions
effect smooth muscle function, influence over sleep cycle and elevation of body temp during fever
Vitamin
essential nutrient unable to be synthesized by the body
Vitamin A
Lipid soluble
carotene, unsaturated hydrocarbon for vision, growth and immune function
aldehyde form retinol is important for light sensiing part of human eye
stored as Retinol, oxidized to retinoic acid to regulate gene expression
Vitamin D
lipid soluble
cholecalciferol, UV reaction in the skin
Vitamin D gets convereted to calcitrol (active form) in liver/kidneys to increase calcium ad phosphate uptake to promote bone production
lack causes rickets, curved bones and impeded growth
Vitamin E
lipid soluble
tocopherols and tocotrenols
aromatic ring with a long isoprenoid side chain and are hydrophobic
biological antioxidants that destroy free radicals to prevent oxidative damage
Vitamin K
lipid soluble
phylloquinone and menaquinones
vital for posttranslational modificatiions required to form prothrombin as clotting factor in blood
introduces calcium binding sites on calcium binding proteins
Triacylglycerols
class of lipids used for energy storage
three fatty acids bonded by esterlinkages to glycerol (usually different FAs)
non polar and hydrophobic
polarity is decreased as the polar hydroxyl groups and carboxylates of fatty acids are bonded together
travel between liver and adipose tissue
characteristics dependent on the saturation of FA chains
Why are lipids good for storage?
carbon atoms of fatty acids are more reduced than sugars which have numberous alcohol groups which means they yield twice as much energy (more energy dense)
hydrophobic to decrease weight and need for hydration
Adipocytes
special cells which store fats and found under skin, abdominal cavity and mammary glands
Free Fatty Acids
unesterified fatty acids with free carboxylate group
circulate in blood noncovalently bonded to albumin
Saponification
ester hydrolysis of triacylglycerols using strong base (lye aka sodium or potassium hydroxide)
sodium slat of fatty acid and glycerol left is the soap
Surfactant
lowers surface tension of the surface of a liquid making it a detergent/emulsifier
Colloid
formed when aqueous solution and oil mix (usually due to introduction of soap)
Micelles
tiny aggregates of soap with hydrophobic tails inward and hydrophillic heads outward which allows for solvation (reason why colloids are made)
nonpolar compounds dissolve in hydrophobic interior of ater solluble micelle, meaning cleaning agent can dissolve both water soluble and water insoluble messes and wash them away
important for absorption of fat soluble vitamins and complex lipids like lecithins
can increase SA for lipolytic enzymes.
