Biochem 2: Lipids and Membranes Flashcards
lipids are a
heterogeneous class of naturally occurring organic compounds
- insoluble in water but soluble in operatic organic solvents
- some are amphipathic
forms of lipids include (2)
- open chain forms
- cyclic forms
open chain forms of lipids
- fatty acids, triacylglycerols, sphingolipids, phosphoacylglycerols, glycolipids
- lipid soluble vitamins
- prostaglandins, leukotrienes, and thromboxanes
cyclic forms of lipids
-cholesterol, steroid hormones, and bile acids
fatty acids are
an unbranched chain carboxylic acid, most commonly of 12-20 carbons
examples include oleic, palmitic, and linoleic
shorthand notation for fatty acids is
carbons : # double bonds
saturated vs. unsaturated
double bonds= saturated (kicks, more tightly packed together, higher melting points)
single bonds - unsaturated
the greater the degree of unsaturation, the _____ the melting points
lower
in most unsaturated fatty acids, the ____ isomer predominates, the ____ isomer is rare
cis isomer predominates
trans isomer rare
triacylglycerol (triglyceride) is an
ester of glycerol with three fatty acids
hydrolysis of triglycerides
can be hydrolyzed with base to yield glycerol and soaps
lipases are enzymes that:
hydrolyze esters in triglycerides
phosphoacylglycerols abundance and where they are found
second most abundant group of naturally occurring lipids, and they are found in plant and animal membranes
phospholipases are
enzymes that hydrolyze specific bonds in phospholipids
what are waxes made up of
a complex mixture of esters of long-chain carboxylic acids and alcohols
where are waxes found
as protective coatings for plants and animals
sphingolipids contain _____ and are found in
sphingosine- a long chain amino alcohol
-found in plants and animals, abundant in nervous system
(structural similarity to phospholipids)
glycolipids
a compound in which a carbohydrate is bound to an -OH group of the lipid
the sugars in glycolipids are mostly
glucose or galactose
-many glycolipids are derived from ceramics
glycolipids with complex carbohydrate that contains more than 3 sugars are known as
gangliosides
structure of steroids
a group of lipids that have fused-ring structure of 3 six-membered rings, and 1 five-membered ring
the molecular basis of membrane structure is in lipid components, describe them
- polar head groups are in contact with the aqueous environment
- nonpolar tails are buried within the bilayer
the major force driving the formation of lipid bilayers is
hydrophobic interaction
the arrangement of hydrocarbon tails in the interior can be either
rigid or fluid
- rigid if rich in saturated fatty acids
- fluid if rich in unsaturated fatty acids
