lipids Flashcards
simple lipids
consist primarily of triacylglycerols
major storage form of fat in adiopocytes
contain one glycerol and three fatty acid chains
longer fatty acid chains contain less water-soluble molecules
what are the three lipid groups
simple (neutral fats)
- a simple lipid is a fatty acid ester of different alcohols and carriers no other substance
compound
- compound lipid are esters of fatty acids with alcohol and possess additional groups. An example compound is a phospholipid
derived
- are the substances derived from simple and compound lipids by hydrolysis. cholesterol steroids, terpens and carotenoids
what are saturated fatty acids
carbon binds to the maximum number of hydrogens
no double bond; fatty acid chains fit close together
occur primarily in animal products and some plants (beef, lamb, pork, egg yolk)
what are unsaturated fatty acids
monounsaturated contain one double bond
polyunsaturated contain two or more double bonds
linolenic acid is an example of an essential fatty acid
triacylglycerol formation (esterification)
fatty acid substrate attaches to coenzyme A to form fatty acyl-CoA which then transfers to glycerol
in
in subsequent reactions two more fatyy acyl-CoAs link to single glycerol backbone to form the composite triacylglycerol molecule
triacylglycerol synthesis increases following a meal for two reasons
food absorption increases blood levels of fatty acids and glucose
relatively high levels of circulating insulin facilitate triacylglycerol synthesis
mobilization of fatty acids via lipolysis predominates under four conditions
low-to-moderate-intensity physical activity
low-calorie dieting or fasting
cold stress
prolonged exercise that depletes glycogen reserves
average person in US consumes about 15% of total calories as
saturated fatty acids
the equivalent of about 23 kg yearly
daily recommended lipid intake
20% of total calories from lipids replace high fat foods with fruits vegetables whole grains fish poultry and lean meat
20-35% of total daily kcal
what are trans fatty acids
derived from partial hydrogenation of unsaturated corn soybean or sunflower oil
what are health concerns of trans fatty acids
increases harmful low density lipoprotein cholesterol
decreases beneficial high density lipoprotein cholesterol
what are compound lipids
triacylglycerol components combined with other chemicals
represent 10% of the lipids in the body
what are phospholipids
compound lipid
fatty acid joined to a phosphate group and nitrogen containing molecule
what are the four main functions of phospholipids
interact with water and lipid to modulate fluid movement across cell membranes
maintain structural cell integrity
play important role in blood clotting
provide structural integrity to the insulating sheath surrounding nerve fibers
what are glycolipids
fatty acids bound with carbohydrate and N2
what are lipoproteins
protein molecule joined with a triacylglycerol or phospholipid
what are the four types of lipoproteins
chylomirons = transport vitamins A,D,E,K HDL = good cholesterol VLDL = transport TAGS to muscle and adopoise tissue LDL = bad cholesterol
what are derived lipids
derived lipids are the substances derived from simple and compound lipids by hydrolysis
what is cholesterol
exists only in animal tissue
does not contain fatty acids but shares some of lipids physical and chemical characteristics
high cholesterol diets can increase risk of coronary heart disease and atherosclerosis
what are the major functions of lipids
energy source and reserve protect vital organs thermal insulation vitamin carrier hunger suppressor
lipid activation
catacholamines
- epinephrine
- norepinephrine
glucagon
growth hormone
cyclic AMP
- cAMP
____speeds up lipolysis & fatty acid activation
exercise
epinephrine increase with exercise
triglycerides are catabolised by lipolysis in ___ of adipocytes; a hormone sensitive lipase (HSL) yielding ___ fatty acids and ___
cytosol
3 fatty acids
glycerol
once a triglyceride is catabolised by lipolysis the fatty acids produced can then __
1) re-esterify
2) enter blood and bind with albumin for transport
____ is not re-used after lipolysis so chemists can measure it as a marker of lipolysis
glycerol
what is the RER
respiratory exchange ratio
the ratio between the amount of carbon dioxide produced in metabolism and oxygen used to create energy from lipid and CHO fuel sources in the body
are RER and RQ the same
no but they are often used interchangeable but differ in how they are applied
fat dynamics during light-moderate intensity exercise
fatty acids provide predominant energy source in light intensity exercise
energy derives from equal amounts of carbohydrates and lipid in moderate intensity exercise
fat dynamics during high intensity exercise
energy derives from carbohydrate, primarily muscle glycogen
