lipids

Question 1

what do lipids typically play roles in

Answer 1

• cell structure, signaling, energy storage

Question 2

what are structural lipids

Answer 2

major component of phospholipid bilayer

Question 3

what are phospholipids

Answer 3

• amphipathic, hydrophilic and hydrophobic regions
• polar head made of phosphate and alc and fatty tail of phosphodiester linkages
• form liposomes and micelles
• diff things can makeup backbone like glycerol of sphingosine

Question 4

saturated vs unsaturated lipid tails

Answer 4

• fully saturated FA tails have only single bonds
• more stable and form solids at room te,p
• unsat have one or more double bonds, creating kinks in chain
• prevents chains from stacking and solidifying so liq at room temp

(why phospholipid bilayer act fluidly at body temp

Question 5

most double bonds in fatty acids are ___ configuration

Answer 5

CIS

• trans manifest when paritally hydrogenated vegetable oils are used in production
• trans dec membrane fluidity and along with saturated FA are associated with inc risk of atherosclerosis

Question 6

what are glycerophospholipids

Answer 6

• contain glycerol backbone
• diff glycerols are in the head group changing the name of the phospholipid
• head group can be charged or neutral, polarity can dictate the role in cell recognition, signaling, binding etc.
• fatty acid chains can vary in length and saturation causing variation in structure

Question 7

what are sphingolipids

Answer 7

• shingosine or shingoid backbone with long non polar fatty acid tails and polar head groups
• an example of a sphingolipid is the antigens on surface of RBC forming basis of ABO blood typing

Question 8

what are waxes

Answer 8

• consist of ester of long chain fatty acids with long chian alcohols
• form malleable solids at room temp and function biologically as protection against the environment
• in humans waces help prevent dehydration and provide lubrication

Question 9

what are the major signaling lipids

Answer 9

steoids, prostaglandins and fat soluble vitamins

Question 10

describe steroid structure

Answer 10

• composed of 4 cycloalkane rings fused together
• functionality depends on oxidation status of rings and functional gorups they carry

Question 11

what is cholesterol why is it important

Answer 11

• major component of phospholipid bilayer and helps maintain the fluidity of the bilayer
• amphiphatic so interacts with both parts of phospholipids to help maintain membrane fluidity
• helps to stablize the cell membrane against changes in temperature and keeps the mambrane from solidifying

also important precurser to toher mol like steroid hormones, biel acids and vitamin D

Question 12

what is the result of too much cholesterol

Answer 12

• high cholesterol = hypercholesterolemia
• correlated with heart disease and an accumulation on walls or arteries leads to atherosclerosis (hardening of arterial walls)
• plaques have potential is dislodge form the surface of the arterial wall and lodge into another aprt of body, if that occurs in the heart can lead to heart attack

Question 13

what is the treatment for hypercolesterolemia

Answer 13

• HMG-CoA reductase inhibitor (atrovastatin and simvastatin)
• inhibit synthesis of cholesterol in liver by blocking key enzyme in cholesterol synthesis pathway
• can also use cholestyramine, which induced the liver to inc synthesis of cholesterol thereby reducing levels stored in liver
• this induces the liver to take up more cholesterol from the blood to reduce circulating cholesterol levels

Question 14

what are prostaglandins

Answer 14

• 20 carbon molecules that are also unsaturated carboxylic acids
• derived from aracchidonic acid and contain 5 membered ring
• many tissues use prostaglandins to regualte the synthesis of cAMP (intracellular messanger) which mediates action of other hormones
• thus prostaglandins ahve dramatic effects on muscle function, the sleep-wake cycle, and elevation of body temp assoicated w/ fever and pain

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Question 15

what are NSAIDs

Answer 15

nonsteroidal anti inflammatory drugs

• ex = ibuprofen and anproxen
• inhibit cyclooxygenase which facilitates prostaglandin production

Question 16

explain fat soluble vitamins

Answer 16

• vitamins = essential nutrients that cannot be mae by the bossy
• water solbule are excreted in urine while lipid soluble can accumulate and store in fat
• therefore can oerdose on the lipid soluble ones like vit A, D, E and K

Question 17

describe vitamin A

Answer 17

• unsaturated hydroarbon with roles in vision gorth and developemnt and immune function
• one metabolite = retinal, a component of the molecular system in the eye that senses light
• the storage form of vitamin A, retinol, is oxidized to retinoic acid which is a hormone that regualtes gene expression in epithelial development

Question 18

describe vitamin D

Answer 18

• also called cholecalciferol

can be formed by a reaction in skin driven by UV light

• liver and kisneys convert it into calcitriol the biologiclly active form
• this inc calcium and phosphate uptake in intestines and dec excretion of calcium by the kidneys
• promotes bone production
• without vitamin D calcium abs is greatly decreased and lack of vitamin D in kids can lead to rickets (underdeveloped and weak long bones) and stunted growth

Question 19

describe vitamin E

Answer 19

• closely related lipids with substitued aromatic ring that is characteristically hydrophobic
• can be powerful antioxidants bc the aromatic ring reacts with free readicals to destroy them
• prevents oxidative damage wich is an important contributor to aging and development of cancer

Question 20

describe vitamin K

Answer 20

• includes a number of compounds and is vital to the formation of prothrombin
• prothrombin is important clotting factor in blood and is required to introduce calcium binding sites on several calcium dependent proteins

Question 21

what is warfarin and how does it work

Answer 21

• commonly used anticoagulant
• inhibits vitamin K epoxide reductase
• this is an enzyme that returns vitamin K to its reduced form after it helps carboxylate prothrombin and other bloo coagulation proteins
• if vitamin K cannot return to reduced form it cannot continue to help orm blood coagulation proteins making patient less prone to clotting

Question 22

what are triacyl glycerols what is their role

Answer 22

• also called triglyccerides
• specifically for energy storage bc carbon atoms of fatty acids are more reduced than sugars (meaning oxidation gives twice as much energy per gram) so they are far more energy dense
• also are hydrophobic and do not draw water, this decreases their weight compared to most other organic mol

*two factors allow triglycerides to be both lightweight and energy rich (excellent for long term energy storage

Question 23

what is the structure of a triglyceride

Answer 23

• three fatty acids bound to a glycerol
• the 3 fatty acids are usually the same
• they are generally non polar and hydrophobic
• triglyceride deposits can be found in the cytool of cells
• the are reserved for metabolic fuel that can be used when energy supplies are low

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Question 24

what are adipocytes

Answer 24

• special cells in animals that store large amounts of fat droplets
• found mainly under the skin, in mammary glands, and in abdominal cavity
• physical characteristics alrgely determined by the sauration of the fatty acids

Question 25

what is soaponification

Answer 25

• hydrolysis of triglycerides by using a strong base (lye)

Question 26

how to free fatty acids ciruclate

Answer 26

bound to albumin

Question 27

how do surfactants work

Answer 27

• lower the surface tension between two soltions
• soap can act as a surfactant acting as detergent or emulsifyer
• help to combine the phases into single phase vai formation of micelles

*micelles with fat can be dispursed trhough the solution

Question 28

how are micelles important in digestion

Answer 28

allow for absorption fo fat solbule vitamins in the body

• secretions of the gall bladder (buile salts) form micelles that allow for th absorption of fatty acids, vitamins and cholesterol from the small intestine
• pancreas also relases enzymes that degrade lipids into fatty acids and cholesterol
• once absorbed these lipdis are converted into triglycerids and packaged for storage