lipids Flashcards
Heterogenous class id naturally occurring organic compounds classified tgt in the basis of common solubility properties
Lipids (fats and oils)
lipids
soluble:
insoluble:
soluble: aprotic organic solvent (diethyl ether, chloroform, acetone, methylene chloride)
insoluble: water bcs of their v. large hydrocarbon chain
*due to their structure
structure of lipid
dominant: water is polar
C-C
C-H
may have:
O-H
P
miscible
soluble
molecule that has one end with a polar, water soluble group and other end with a nonpolar HC grp that is insoluble in water
amphipathic
has polar and nonpolar parts
*dominant: np, esp in water
classification of lipids
- open chain compounds:
- fused ring compounds:
open chain compounds: (mas varying daw)
fatty acids
TG
sphingolipids
phosphoacylglycerols
glycolipids
fused ring compounds:
cholesterol
steroid hormones
bile acids
unbranched chain carboxylic acids
fatty acids
12-20 long (even no. of carbons)
derived from hydrolysis (of animal fats, vege oils etc)
hydrolysis - breakdown of water
amphitic compounds of fatty acids
nonpolar
polar:
nonpolar: HC
polar: COOH
types of fatty caids
contain c=c:
contain c-c:
contain c=c: unsaturated
contain c-c: saturated
in unsaturated fatty acids,
cis isomer predominated
trans isomer is rare
cis isomer predominated:
same side
trans isomer is rare:
diff side
melting point of the fatty acids depends on the
length of chain
degree of unsaturation (no. of double bonds)
is an unsaturated fatty acid with its endmost double bond three carbon atoms away from methyl end
omega 3 fatty acids
it is accumulated in adipose tissues and provide a means of storing fatty acids
triacylglycerols (triglycerides)
ester linkage are hydrolyzed by lipase
stores oof metabolic energy
reaction of glyceryl ester with NaOH or KOH t produce glycerol and respective Na or K salts
saponification
compounds in which 2 fatty acids and phosphoric acid are esterified to the 3 hydroxyl grps of glycerol
phosphatic acid
why is the head of the fatty acids are charged
as it contains phosphate group - that ionized at neutral pH
*positively charged amino grp by an amino alcohol esterified to the phosphoric acid
complex mixtures of esters of long chain carboxylic acid and long chain alcohols
waxes
*serve as a protective coating for plants and animals
primary alcohol of sphingosine is esterified to phosphoric acid which is esterified to choline
sphingomyelin
lipid to which a sugar moiety is bonded
glycolipids
parent compound of glycolipids
ceramides
it is formed between the pri alcohol grp of ceramide and a sugar residue (glucose or galactose )
glycosidic bond
= result compound called a cerebroside
glycolipids with a complex carbs moiety that contains 3 sugars
gangliosides
-one is always a sialic acid
-has negative charge at neutral pH
lipids with a characteristics fused-ring structure
steroids
where does cholesterol occur
cell membrane
- highly hydrophobic
- precursors: can derive to t=other structures
what is the major force that is driving the formation of lipid bilayers
hydrophobic interaction
membrane fluidity
linear arrangement of HC chain leads to rigidity -
kink in the HC chain causes disorder in its packaging in and leads to greater fluidity -
linear arrangement of HC chain leads to rigidity - saturated fatty acids (rigid = cant movee)
kink in the HC chain causes disorder in its packaging in and leads to greater fluidity - unsaturated fatty acids (has bends and have spaces between FAs = more loose packing = greater fluidity)
true or false:
presence of cholesterol can enhance order and rigidity
true
as fused ring of cholesterol is rigid
true or false:
plant membrane are less fluid and more rigid than animal membrane
false
animal membrane (contain cholesterol ) are less fluid and more rigid than plant membrane (hv unsaturated fat)
true or false:
membranes oof prokaryotes are the most fluid
true
most - least
prokaryotes > plants > animals
true or false:
ordered bilayers become more ordered in the presence of heat
false - loosely packed
high temp, high fluid
gel > liquid (in the presence of heat)
this type of protein is loosely bound to the outside of a membrane
peripheral proteins (Heterotrimeric G protein)
this type of proteins are embedded in a membrane
integral proteins (Rhodopsin)
* can be removed y treatment with detergents or extensive = denaturation of protein
what type of bonds can do proteins anhored to the lipids
covalent bonds
transport proteins:
receptor proteins:
transport proteins:
mediate the entry of specific substances into a cell
receptor proteins:
contains specific binding sites for extracellular subs
model in which proteins and a lipid bilayer exist side by side without covalent bonds between them
fluid-mosaic model
term that implies that there is lateral motion of components in the membrane
fluid mosaic
process by which a substance enters a cell w/o expenditure of cell energy
passive transport
*driven by conc. gradient - from high to low
what are the 2 categories of passive transport
simple diffusion:
dont need anything daw
without requirement for a carrier
facilitated diffusion:
binding a carrier protein
does not require energy
substances is moved against a conc gradient
active transport
*need energy from low to high
pri active transport:
directly linked to hydrolysis like ATP
sodium-potassium ion pump
sec active transport:
driven by H+ gradient
proton pump
it is a principal carrier of cholestrol in the bloodstreem
low-density lipoprotein (LDL)
consists of various proteins and lipids
lipid soluble vitamins
hydrophobic
vitamin A D E K
