HUN 3224 exam 3 farrel lipids fsu

how many carbons long is a fatty acid chain?

4-24 carbons long

how many carbons does a fatty acid need to be considered "nutritionally significant"?

14 or more

saturated fatty acids

solid at room temp. all carbons have hydrogens. no double bonds

Where do saturated fats come from?

animal sources and tropical sources

monounsaturated Fatty Acids

A fatty acid with only one double carbon bond.

Where do monounsaturated fats come from?

olive oil, canola oil

polyunsaturated Fatty Acids

fatty acids with more than one double bond.

polyunsaturated Fatty Acids predominant form?

Cis Form

what does hydrogenation do?

forms trans fats by adding hydrogens to unsaturated fats to make them solid at room temp

When is Hydrogenation often used?

Commercially processed foods

Ex: Crackers, cookies, snack cakes, etc.

what does it mean if a fatty acid has fewer double bonds?

it lasts longer

we humans lack the enzyme to add carbon double bonds past which carbon?

delta 9

CH3 nomenclature

omega or n end

COOH nomenclature

alpha or delta end

How to name a fatty acid.

1. count the number of carbons.

2. count the number of double bonds.

3. Name according to omega or alpha end.

Eicosanoids

hormone-like substances involved in inflammation, blood clotting, blood pressure, nervous system, immunity, and smooth muscle contraction

Eicosandoids are changed from ___ chain to __ carbon fatty acid

18,20

Where are eicosanoids produced?

in the cell that it acts upon

eicosanoid familes

prostacyclins, thromboxanes, leukotrienes, prostaglandins

what are eicosanoids synthesized from?

arachidonate acid, eicosatrieonic acid, eicosapentanoic acid

Prostacyclins

Site of synthesis: Vascular endothelium

Mode of action: vasodilator, platelet anti aggregation

Thromboxanes

Site of synthesis: Platelets

Mode of action: Vasoconstrictor, platelet aggregation

Leukotrienes

Site of synthesis: Leukocytes

Mode of action: Vascular contraction, inflammation

Prostaglandins

Site of synthesis: Endothelium of a variety of cells

Mode of action: Vascular smooth muscle contraction or relaxation

What does desaturase do?

add carbon double bond

what does elongase do?

adds 2 carbons to carboxyl end

if eicosatrienoic goes to the cox pathway, is it pro or anti inflammatory?

anti-inflammatory

if arachidonic acid goes to the cox pathway, is it pro or anti inflammatory?

pro-inflammatory

if lipoxygenase is used on arachdonic acid, what does it go on to become?

leukotrienes and lipoxins

What makes up a triglyceride?

glycerol backbone and 3 fatty acids

how many carbons in a glycerol backbone?

3 carbon chain

what makes up a phospholipid?

glycerol backbone, 1 or 2 fatty acids, and a phosphate group

What is a glycolipid?

lipid with carbohydrate attached

Sterols

cant be broken down for energy. contain steroid nucleus

What does cholesterol do?

create bile acids, steroidal sex hormones, make vitamin D, and makes adrenocortical hormones

What is lingual lipase?

enzyme "begins" the digestion of fat in the mouth. Breakdown of triglycerides in mouth. Efficient digestion of milk fat(infants)

Biliary emulsification

Emulsification is the dispersion of fat in an aqueous solution (this allows for lipase action)

What is an emulsifying agent?

Bile salt

3 main enzymes involved with lipolysis?

pancreatic lipase, cholesterol esterase, and lecithanse

pancreatic lipase

made in the pancreas and used to breakdown triglycerides

What is lipolysis?

breakdown of lipids

What are micelles?

clusters of bile salts that transport lipids across the cell membrane of the villi

what kind of diffusion do micelles undergo and where?

passive diffusion in the duodenum and jejunum

after fats are able to passively move into the cell, what happens to bile salts?

bile salts are absorbed in the illeum and returned to the liver via the enterohepatic cycle (EHC)

once inside the enterocyte, what acts on the lipids and cholesterol?

CoA works on lipids, and fatty acids are added to cholesterol

what does CoA and fatty acids do to lipids and cholesterol?

turns them into triglycerides and cholesterol esters

What is a chylomicron?

type of lipoprotein formed in enterocytes to transport lipids away from the GI tract

what makes up a chylomicron?

triglyceride, fatty components, and protein

what does a short chain fatty acid (<12) attach to in order to move out of the enterocyte?

albumin

Lipoproteins

Complexes which carry lipid products in the blood and lymph to various tissues.

Where does the chylomicron go?

into the lymph system

Function of Chylomicron

Transport exogenous triglycerides to tissues.

What is lipoprotein lipase?

enzyme that hydrolyzes triglycerides in lipoproteins into free fatty acids and glycerol, allowing the uptake of fats by tissues

chylomicron remnant

the lipoprotein particle that remains after a chylomicron has lost most of its fatty acids. taken up by hepatocytes in the liver via receptor mediated endocytosis

Where are VLDLs synthesized?

liver

what does VLDL do?

transports lipids (mainly triglycerides) from the liver to extra-hepatic tissues

How are IDLs formed?

when VLDLs lose triglycerides from hydrolysis via LPL

How are LDLs formed?

when VLDLs lose triglycerides through lipoprotein lipase in bloodstream, leading to a higher proportion of cholesterol.

What does LDL do?

delivers hepatic cholesterol to peripheral tissues

where are receptors for receptor mediated endocytososis found?

located in clatharin coated pits

receptor-mediated endocytosis receptors

specific proteins that bind molecules, allowing entry into the cell through vesicle formation

Steps of receptor-mediated endocytosis

1. LDL and receptor come together forming a complex an move into cell.

2. complex gets surrounded by lysosomes and cholesterol esters released from complex into the cell.

3. complex moves back out of the cell and the receptor goes back outside to receive another protein

what does a lysosome do when it attaches to LDL-receptor complex?

changes the PH

HMG-CoA reductase

rate limiting enzyme for cholesterol synthesis

if cholesterol in the cell is high, what happens to LDL receptor synthesis?

it decreases, therefore LDL remains in blood

Where is HDL made?

liver and intestines

what does HDL do?

removes cholesterol from non-hepatic tissue and transports cholesterol esters to liver.

function of LCAT

an enzyme that transfers an acyl from a lecithin to a free cholesterol forming a cholesteryl ester which goes into an HDL for transport to the liver

approximately how much cholesterol is made in the body?

about half. 50%

what causes the reduction of HMG reductase?

high cholesterol in cell, fasting, glucagon, glucocorticoid hormones

what is the RDA for cholesterol? how much do we actually eat?

300mg/day is RDA. we eat about 600mg per day

When dietary cholesterol goes up, synthesis goes

down

When dietary cholesterol goes down, synthesis goes

up

HDL

High density lipoprotein transports cholesterol from tissues to liver

LDL

Low density lipoprotein transports cholesterol from liver to tissues.

Bile composition

82% water

12% bile salts

4% phospholipids

0.7% free cholesterol

Electrolytes

Bile pigments

fiber effects on cholesterol

causes bile to be excreted instead of being recycled, which means cholesterol in body is used, lowering overall cholesterol levels

what acts on glucose to make G6P?

glucokinase +insulin

what happens if there is a lot of citrate in the cell?

the citrate will exit the cell into the cytosol to go on to become fat

what turns citrate back into acetyl CoA?

citrate cleavage enzyme ( citrate loses OAA)

what happens after malonyl CoA is made?

fatty acid synthase acts upon it adding 2 carbons each turn until 16 carbons are reached

fatty acid synthase enzymes

dimer of 2 identical polypeptide monomers

where does elongation and desaturation occur?

endoplasmic reticulum

de novo fatty acids

16 carbons long. first double bond at the n9 position

What is beta oxidation?

the process of Converting fatty acids to Acetyl-CoA for energy

high levels of malonyl CoA

high levels inhibit carnitine acyl/ palmitoyl transferase 1

Low levels of malonyl CoA

allow for production of CAT-1/CPT-1

during cholesterol synthase, which steps utilize 1 NADPH per step?

beta-hydroxy-beta-methyl into melvonate and fersynl pyrophosphate into squalene

during cholesterol synthase, which step utilizes 2 ATP's?

mevlonate into fersynl pyrophosphate

which step utilizes HMG-CoA reductase?

beta hydroxy beta methyl into mevlonate