Chapter 4 - Lipids

Question 1

Lipids

Answer 1

a diverse group of compounds that are largely nonpolar in nature
-hydrocarbons that include mostly nonpolar carbon-carbon or carbon-hydrogen
-nonpolar molecules = hydrophobic, insoluble in water
-cells store energy (long term) in fats, provide insulation from the environment for plants/animals
-lipids = building blocks of many hormones, an important constituent of all cellular membranes
-includes fats, oils, waxes, phospholipids, steroids

Question 2

3 Most Important Lipids Classes in Body

Answer 2

triglycerides, sterols, phospholipids

Question 3

Fat Molecule

Answer 3

has 2 main components:
-glycerol: organic compound (alcohol) with 3 Carbons, 5 Hydrogens, and 3 Hydroxyl (OH) groups
-Fatty Acids : long chain of Hydrocarbons to which carboxyl group is attached, # of Carbons range 4-36, most common is 12-18 carbons; has a carboxyl group/hydrocarbon group/methyl group

Question 4

Fats have 2 Characteristics:

Answer 4

insoluble in water
organic (carbons with covalent bond)

Question 5

Ester Bond

Answer 5

between glyceride and fatty acid –> C-O-C = O

Question 6

Saturated Fatty Acid

Answer 6

only single bonds with neighboring Carbons in the hydrocarbon chain
-has max. number of H
-straight & solid at room temp
-increases levels of “bad” cholesterol (low density lipoproteins)
-LDLs clogs arteries
-includes meat, butter, dairy products

Question 7

Unsaturated Fatty Acid

Answer 7

have one or more double bonds so missing 2 or more Hydrogens
-double bond causes bend so not straight and liquid at room temp (can’t stack compactly)
-increases level of “good” cholesterol (high-density lipoproteins)
-HDL gabs LDL and escorts to liver where LDL is broken down and removed from body
-includes vegetable oil
-has two categories: cis and trans

Question 8

Cis Unsaturated Fats

Answer 8

-common in nature
-H on same side of carbon atoms
-bend in FA chain
-low melting point
-liquid at room temp

Question 9

Trans Unsaturated Fats

Answer 9

-rare in nature/made artificially (hydrogenation - Hydrogen gas bubbled thru oils to solidify)
-H on opp side of carbon atoms
-straight
-solid at room temp
-ex) margarine, some peanut butters, shortening

Question 10

an increase in trans fats in diets causes…

Answer 10

an increase in low-density lipoproteins or “bad” cholesterol which leads to plaque deposition in arteries and heart disease

Question 11

Omega Fatty Acids

Answer 11

-omega 3,6,9 are essential fatty acids that the human body requires but does not synthesize, have to be supplemented through ingestion via diet
-one of only 2 EFA known for humans
-farther C away from carboxyl group # is the omega carbon

Question 12

Eicosanoids

Answer 12

-made in the liver where carbon is added until the chain contains 20-22 carbons
-“local” hormones: inflammatory processes, blood vessel dilation, constriction
-“heart healthy” effects of dilating blood vessels, discouraging blood clotting and reducing inflation

Question 13

Omega 6 Fatty Acids

Answer 13

-linoleic acid : arachidonic acid –> eicosanoids
-good sources: seeds, nuts, vegetable oil
-Food sources = plant foods, flaxseed, soybean oil, canola oil, walnuts, salmon, chia seeds
-associated with increased inflammation
& cardiovascular disease

Question 14

Omega 3 Fatty Acids

Answer 14

-associated with decreased inflammation & cardiovascular disease
-found in fish oils

Question 15

Waxes

Answer 15

covers some aquatic bird feathers and some leaf surfaces
-hydrophobic nature: prevent water from sticking on the surface
-long fatty acid chains esterified to long-chain alcohols

Question 16

Phospholipids

Answer 16

-major plasma membrane constituents that comprise the cell’s outermost layer
-comprised of 2 fatty acids, 1 glyceride, 1 phosphate
-is amphipathic molecule: has a hydrophilic (phosphate-containing group that interacts with water; head) and hydrophobic (fatty acid chains, can’t interact with water; tail) part; can form micelle rings which are important for certain cellular organelles like liposomes

Question 17

Phospholipid Bilayer

Answer 17

-in the membrane, a bilayer of phospholipids forms a structures matrix - the fatty acid tail faces inside, away from water, and the phosphate group head faces the opposite way, outside, toward the water
-receptors in the bilayer grab needed things, the hydrophilic/phobic properties remove bad/unneeded things
-includes cholesterol: helps support the structure and increases hydrophobicity
-includes proteins: transport molecules
-bilayer is an emulsifier: keeps fat in water, allows oil and water to mix
-perfect structural element for cell membranes: able to communicate with watery environments of blood and cell fluids
-allows other lipids to enter/exit the cell

Question 18

Sterols

Answer 18

-uncommon; does not resemble other lipids but scientists group it with them because it is also hydrophobic and insoluble in water
-found in the phospholipid bilayer, component of plasma membrane
-fused ring structure
-plants, animals, fungi
-4 carbon ring structure with different functional groups attached (many have OH- functional group –> puts them in alcohol classification)
-cholesterol is the most common sterol in animals

Question 19

Cholesterol

Answer 19

-maintains fluidity and flexibility in the membrane
-decreases the permeability of the membrane
-fills spaces left by kinks of unsaturated FA tails
-foods high in cholesterol: beef brain, chicken liver, egg yolk, shrimp, cheeseburger, chicken legs
-cholesterols can be up to 50% of animal cell membrane

Question 20

Lipoprotein

Answer 20

-lipid + protein, found in blood
-packages carrying cholesterol and other hydrophobic lipids that cannot dissolve in blood
-contain fat on inside and protein on outside
-ratio with triglycerides > protein –> LDL (not good)
-ratio with triglycerides&raquo_space; protein –> very LDL (very not good)
-ratio with triglycerides < protein –> HDL (better)

Question 21

Chylomicron

Answer 21

-ULDL
-more triglyceride
-LDL = bad cholesterol
-more cholesterol… stick to artery… build up… clogs arteries… heart failure