Biochem CH. 11

lipids are soluble in

organic solvents

5 classes of lipids

• free fatty acids

• triacylglycerols

• phospholipids

• glycolipids

• steroids

free fatty acids func

common fuel

triacylglycerols

storage form of fatty acids

phospholipids are

membrane lipids

glycolipids

membrane lipids composed in part of carbohydrates

steroids

polycyclic hydrocarbons w/ a variety of func

fatty acids structure

chains of hydrogen-bearing carbon atoms

• carboxylic acid at one end

• methyl group at other end

main source of fuel

fatty acids

fatty acid carbons are usually numbered beginning with

carboxyl terminal atom

omega carbon is the

met

△⁹ means…

double bond between carbon 9 & 10

when double bonds present in fatty acids, what usual configuration

cis configuration

fatty acid chains usually contain what kind of number of chain

even number

• usually 16-18 carbon atom

polyunsaturated acids have what separating their double bonds

methylene group (CH2)

the properties of fatty acids depend on what 2 things

chain length & degree of unsaturation

short chain length relates to temp how

low melting temp

double bonds leads to

less hydrophobic interactions

2 things that can influence fluidity of fatty acids

short chain length & presence of double bonds

(low MP + less hydrophobic interactions)

2 things that determine MP of fatty acids

shape (sat or unsat)

• unsat = double bonds —> less  hydrophobic interactions —> decrease MP

chain length

• longer chain —> more hydrophobic interactions —> increase MP

what types of fatty acids are essential to our diet/cannot be synth by humans

cis polyunsaturated fatty acids

cis polyunsaturated fatty acids are precursors to

a variety of hormones

which type of fatty acids offer protection from coronary heart disease

cis polyunsaturated fatty acids offer protection

triacylglycerols aka triglycerides structure

3 fatty acids joined in ester linkage + glycerol backbone

• C#2 ususually has unsat. fatty acids

triacylglyerols nomenclature

1. beginning fatty acids lose “-ic acid” —> change to “-oyl”

2. only last fatty acid keeps whole name

(ie: 1-hexadecanoyl-2-(9)octadecenoyl-3-hexadecanoic acid)

fatty acids are stored as

triglycerols/triglycerides

where is the major site for triacylglycerol storage in mammals

adipose tissue

soaps

sodium or potassium salts of fatty acids

how are soaps generated

triacylglycerols are treated w/ strong base

triacylglycerols components

• energy rich

• hydrophobic

• stored when excess glucose in adipose tissue

• used when no more glucose

3 types of membrane lipids

phopholipids, glycolipids, cholesterol

phospholipids structure (4)

• 2 fatty acids

• platform (glycerol or sphingosine)

• phosphate

• alcohol

2 common plaforms of phospholipids

glycerol & sphingosine

glycerophospholipids strucutre

• 2 fatty acids

• glycerol backbone

• phosphate

• alcohol

glycerophospholipids features

• contains polar group (@ pos. 3 instead of another fatty acid)

• amphilic nature (polar/nonpolar)

glycerophospholipids are susceptible to cleavage by

phospholipases

prostaglandins & thromboxanes are involved in what

blood clotting

what inhibits blood clotting

aspirin

leukotrienes

involved in allergy attacks & asthma

phosphatidlyinositol

increases Ca2+ in cytosol

diacylglycerol

activates protein kinase

increase in Ca2+ leads to

increase in aerobic respiration enzyme activity

sphingolipids are phospholipids..

phospholipids built on sphingosine platform

sphingolipids

• major membrane components of neurons for nerve sheath

• can serve as signaling molecule

sphingolipids structure

• contains trans double bond

• sphingosine parent compound

sphingosine are more stable than ______ due to _______

glycerophosphate due to amide linkage

ceramides

simplest sphingosine; only has fatty acid

(no sugar/polar groups)

sphingomyelin

major component of nerve sheath

multiple sclerosis is caused by

destrucution of nerve sheath by autoimmune or virus

in sphingomyelin, if A has FA attached and B has phosphatidylcholine or phosphatidylethanolamine it can lead to

sphingophospholipid

• destroys nerve sheath —> multiple sclerosis

in sphingomyelin, if A has FA attached, what does B need to have tolead to multipl sclerosis/sphingophospolipid

B has either

• phosphatidylethanolamine

• phosphadylcholine

cerebroside structure

has monosaccharide @ B and FA @ A

what’s the simplest glycolipid

cerebroside

ganglioside structure

• 3-30 sugar residues @ B

• FA @ A

ganglioside func

receptors for pituitary glycoprotein in hormones

if ganglioside can’t be broken down —> leads to

sphingolipid storage diseases

glycolipids (def)

carbohydrate-containing lipids; also a membrane lipid

glycolipids role in cell membrane

cell-cell recognition on extracellular surface

steroids structure

• built on tetracyclic platform

• 3 cyclohexane rings + 1 cyclopentane ring fused together

cholesterol is a precursor to

steroid hormones & some vitamins

most common steroid

cholesterol

glucocorticoids (steroid) func

carb, lipid, protein, metabolism

aldosterone (steroid) func

excretion of water + salt from kidneys

androgens & estrogens (steroids) func

sexual characteristics

3 lipid soluble vitamins

vitamin A, E, K

vitamin A func

assists in vision

vitamin E func

antioxidant —> reduces oxidizers

vitamin K func

assists in blood clotting

what parts of the membrane lipid provide hydrophilic properties

alcohol & phosphate components (polar head)