Lipids and Membranes

fatty acids

consists of hydrophobic tail and a carboxylic acid

saturated fatty acid

fatty acid with no double bond

unsaturated fatty acid

fatty acid with a double bond; can be cis or trans

cis

unsaturated fatty acids found in nature are usually ___ in conformation

stronger

the longer the fatty acid tail, the ___ the hydrophobic and VdW interactions are

acetic acid

C2:0

capric acid

C10:0

lauric acid

C12:0

stearic acid

C18:0; 5% of all human fat

palmitic acid

C16:0; 26% of all human fat

palmitoleic acid

delta⁹ C16:1

oleic acid

delta⁹ C18:1

linoleic acid

delta^9,12 C18:2

gamma-linoleic acid

delta^6,9,12 C18:3

alpha-linoleic acid

delta^9,12,15 C18:3

omega

nomenclature of unsaturated fatty acids that requires numbering to start from the non-carboxyl end of the acid

trans

___ unsaturated fatty acids behave similarly to saturated fatty acids

partial hydrogenation

converts cis double bonds into single bonds or trans double bonds

six

fatty acids are water soluble until carbon ___

glycerol

backbone of triacylglycerol

esterfication

triacylglycerols are formed from the ___ of glycerol

triacylglycerol

storage lipid that provides stored energy and insulation as fat

• carbon of fatty acid tail is in the most reduced form of carbon

• not hydrated so light and easy to store

glycerophospholipids

membrane lipids with a glycerol core, 2 fatty acids, and a phosphate group attached to a varying head group

phosphatidyl ethanolamine

zwitterion

phosphatidyl choline (lecithin)

zwitterion

phosphatidyl serine

-1 charge

phospholipase A1

cuts the first fatty acid tail off a phospholipid

phospholipase A2

cuts off the second fatty acid off a phospholipid

phospholipase C

cuts phosphate group + head group off a phospholipid

phospholipase D

cuts off head group from phospholipid

sphingolipids

___ have a sphingosine backbone

hydroxyl

the ___ group attached to the same carbon as the long hydrocarbon chain a sphingolipid does not participate in bonding

sphingosine

ceremide

sphingolipid before a polar head group is added

glycosphingolipid

sphingolipid with a sugar attached instead of a phosphate head group

• no charge

• on the outer plasma membrane

• important to cell-surface recognition tasks like identification of blood types in RBCs

cerebrosides

glycosphingolipid with 1 sugar unit as the head group

globosides

glycosphingolipid with more than 1 sugar unit as a head group

gangliosides

glycosphingolipid with oligosaccharides as a polar head group and 1 or more residues of N-acetylneuraminic acid

• only oligosaccharide that is negatively charged

• contains sialic acid at the terminal

simple lipids

lipids with no fatty acids; made of isoprene units

terpenes

simple lipids made up of isoprene units stacked head to tail; forms vitamins

beta-carotene

tetraterpene (C₄₀) needed for vision

vitamin D₃

cholecalciferol; formed in the skin by a UV-induced photochemical reaction; regulates calcuim levels in the body

vitamin E

a group of tocopherols each containing an aromatic ring and a long isoprenoid side chain; functions as biological antioxidants

vitamin K

unsaturated hydrophobic chain attached to napthoquinone; used to synthesize prothrombin (blood-clotting factor)

electron carriers

coenzyme Q (ubiquinone) and plastoquinone are simple lipids which are also ___

steroids

simple lipids comprised of a 4-fised ring steroid nucleus which is nearly planar

lipoprotein complexes

cholesterol is transported in ___ vesicles in the blood stream

cholesteryl esters

cholesterol esterfied when in lipoprotein through the addition of a fatty acid to the -OH

peripheral membrane proteins

detaches easily from the bilayer with the help of a high salt concentration if they are electrostatically attached to the membrane

integral membrane proteins

embedded into the biomembrane so external surfaces are hydrophilic and surfaces inside the membrane are hydrophobic

• can be an alpha-helix, 4-12 alpha-helices, and 8-16 beta-strands forming a beta-barreled porin

• forms transmembrane transporters

GLUT 1

glucose permease; passive uniport transporter of glucose in erythrocytes

• reversible conformational change allows for transport

• made from 12 alpha-helices working together to form a pore

chloride-bicarbonate exchanger

passive transport of bicarbonate

respiring tissue

in ___ chloride-bicarbonate exchanger brings bicarbonate into the cell while pumping chloride ions out of the cell

primary active transport

coupled to an exergonic chemical reaction like ATP

secondary active transport

uses energy from the movement of ions cause by primary active transport to fuel its processes (cotransporter)

polyunsaturated fatty acids

PUFA: fatty acids with more than 1 double bond

eicosapentaenoic and docasahexanoic acid

EPA (delta^5,8,11,14,17 C20:5) and DHA (delta^{4,7,10,13,16,19} C22:6) are acids synthesized from alpha-linoleic acid

sphingomyelin

sphingolipid with phosphocholine as a head group