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85 Cards in this Set
- Front
- Back
What 2 classes are lipids broken into? |
1) Those based on fatty acid Structures 2) Those based on isoprenoid structures |
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What are the different types of fatty acids? |
1) Cis - more fluid and low melting point 2) Trans - less fluid and higher melting point 3) Saturated - less fluid and higher melting point |
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What fatty acids are the worse for your health? |
Saturated and Trans Fats |
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Where are saturated fats found? |
Meat and dairy products |
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Where are trans fats found? |
Most are made in the hydrogenation process |
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What is partial hydrogenation? |
Removes many of the cis bonds, but in the process converts the remaining ones the trans configuration |
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Why would you want to partially hydrogenate fats? |
Trying to make oils solid and make them easier to work with. Increases shelf life |
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Difference in fat content between butter and margarine |
Margarine - increased trans fats Butter - increased saturated fats |
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What are the essential fatty acids? |
1) Omega-3 - alpha linoleic acid High levels in fish 2) Omega-6 - linoleic acid High in vegetable oils |
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What kind of problems occur with too much omega 6 intake? |
Promote inflammation and increase the risk of heart disease |
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What are eicosanoids derived from? |
Arachidonic acid or any 20 carbon fatty acid |
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What are examples of eicosanoids? |
Prostaglandins, thromboxanes, and leukotrienes |
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Eicosanoids are physiological mediators of many processes such as: |
Inflammation Vasodilation/constriction Bronchodilation/constriction Vascular permeability Platelet aggregation |
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What is the major component of waxes? |
An ester of long-chain fatty acids and long-chain alcohol |
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What are some uses of waxes? |
1) Protective coating on plants and fur and skin of animals 2) Wax esters are components of beeswax, carnauba wax, ear wax |
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What are the physiological roles of TG's? |
Insulation Energy Storage |
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Does glycogen or TG's store energy more effectively? |
TG's - oxidation of fats = more ATP more places to oxidize due to more hydrogens attached to the carbons vs glycogen some hydrogens are attached to oxygens instead Glycogen is more polar - water will come along and fill empty space causing decreased glycogen in one given area. TG's are not polar and will not bring water leading to more storage capacity |
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What else can TG's participate in besides energy and insulation? |
1) Saponification - creation of soap 2) Emulsification - dispersion of one liquid in another (i.e. oil out) |
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Saponification |
Heating of an ester in the presence of a base to create a soap. Fatty acid salts create micelles around dirt. |
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Why are micelles not a bilayer? |
These only have one fatty acid chain versus 2 fatty acid chains. |
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Where does Lipogenesis of TG's occur? |
Cytosol of liver cells and adipocytes |
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What are the substrates for TG lipogenesis? |
Fatty acyl CoA's - made by adding a fatty acid to CoA Glycerol - 3 - phosphate - the backbone |
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Lipolysis |
Releases fatty acids from TG's |
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Where does lipolysis occur? |
Done in adipocytes when fatty acids are needed for energy ( i.e. fasting, exercise, stress, etc.) |
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How is lipolysis activated? |
TG lipase which is hormone sensitive lipase (HSL) |
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What are the products of Beta oxidation? |
3 fatty acids and glycerol backbone |
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What activates HSL? |
Epinephrine - fight or flight - increased energy Glucagon - low blood sugar - need more energy |
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What inactivates HSL |
Insulin - when we already have lots of glucose for energy |
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How is glycerol processed after lipolysis |
Released into blood and taken up by the liver Liver contains Glycerol Kinase |
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What does Glycerol Kinase do in the liver? |
- Glycerol to G3P - TG's - Phospholipids - DHAP to go in reverse and make glucose |
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How are fatty acids processed after lipolysis? |
Carried in blood and transported into tissues Used for energy in various tissues |
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Where are fatty acids used heavily? |
Cardiac Muscle |
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Where are fatty acids not used? |
RBC's and brain |
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What two different types of backbones can phospholipids have? |
1) Glycerophospholipids/ phosphoglycerides - glycerol backbone 2) Sphingomyelins - ceramide backbone |
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Both phosphoglycerides and sphingomyelins contain: |
Hydrocarbon chains Polar Phosphate-alcohol head group |
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Phosphtatidates |
Both fatty acids are in an ester link Example: membrane components such as phosphatidylcholine |
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Plasmalogens |
One fatty acid is an ether link and one in an ester link Example: Platelet activating Factor |
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Phosphoglyceride uses |
Emulsifying agents Surfactants - polar parts can disrupt H bonds and lower the surface tension of water Membrane Components |
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Importance of Surfactants in infants |
Lack of certain phospholipids that make up lung surfactant is a major cause of respiratory distress syndrome in premature babies |
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Why a phosphate alcohol head group in phospholipids? Doesn't look like an alcohol?? |
The alcohol is removed when attached to the phosphate |
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Varying phosphate head groups in phospholipids |
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How do you make membrane phospholipids i.e. phosphatiylcholine? |
Start on the cytoplasmic side of the SER and add a phosphocholine head group to DAG |
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How does DAG become TAG? |
Add an acyl CoA |
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What is another way to make phosphatidylcholine? |
1) Make phosphatidylethanolamine first - add phosphoethanolamine from CDP-ethanolamine to a DAG backbone 2) Methylate the PE to create PC |
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Where do methyl groups come from? |
SAM - S-adenosyl methionine |
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What vitamins help SAM function? |
B9 and B12 (Cobalamin) |
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How do you get some of the newly made phospholipids to the other side of the bilayer membrane? |
A special flippase enzyme will translocate various phospholipids across the membrane |
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How do you get the newly made phospholipids from the SER membrane to the cell membrane? |
Pieces of SER contain the new phospholipid bud off as little vesicles and re-insert into the plasma membrane |
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Fatty Acid Functions |
1) Broken down for energy via beta oxidation 2) Can be used to make membranes 3) Form various derivatives - Sphingolipids, waxes, TG's, Eicosanoids |
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Sphingomyelin Structure |
Ceramide Backbone Phosphocholine Polar head group Hydrocarbon Chains (palmitate) |
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What makes up ceramide? |
Sphingosine and a fatty acid |
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Cerebrosides |
Ceramide backbone Monosaccharide head group Common in neuronal membranes |
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Sulfatides |
Ceramide backbone Sulfated monosaccharide head group Common in neuronal membranes |
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Glycosphingolipid examples |
Neutral : Cerebrosides Acidic: Gangliosides and Sulfatides |
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Gangliosides |
Ceramide Backbone Head group: 1 or more sialic acid residues plus one ore more monosaccharides Common in neuronal cell membranes |
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GM2 |
G = Ganglioside M = Number of sialic acids - mono = 1 2 = Pattern of monosaccharide attachment |
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Tay-Sachs Disease |
The accumulation of GM2 in lysosomes due to an enzyme deficiency The most sever excess if in the brain and that build up leads to neuronal cell damage Death early as 5 years of age |
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How many carbons are in an isoprene unit? |
5 carbon unit |
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What is an example of an isoprenoid? |
Terpenes - lipids comprised of various numbers of isoprene units |
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Examples of terpenes: |
Beta carotene Squalene - makes cholesterol Citronella |
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T/F The smallest isoprenoid is made up of 2 isoprene units |
True - So monoterpene actually has 2 units instead of 1 |
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What is a mixed terpenoids? |
Mixed terpenes are non-terpene molecules with terpenes attached |
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3 examples of mixed terpenoids |
Vit. K Coenzyme Q Amino acids with isoprene attached - Prenylated protein |
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Steroids |
Isoprenoids Complex molecule made of 6 isoprene units |
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How can you identify Sterols? |
Steroid with a hydroxy group at C3 |
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T/F All steroid hormones are derived from terpenes |
False, all steroid hormones are derived from cholesterol |
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How can you tell if it's testosterone or progesterone |
There will be a double bonded O at C-3 instead of the OH like in sterols |
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Synthesis of Isoprenoids |
Isoprene units are donated from isopentyl pyrophosphate - you need a carrier molecule |
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What are the three main steps of cholesterol synthesis? |
1) Formation of isopentenyl pyrophosphate 2) Creation of squalene 3) Cyclization of squalene into cholesterol and addition of hydroxy group |
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Step 1 of Cholesterol Synthesis: |
3X Acetyl CoA to HMG CoA (can also go to ketogenesis) to Mevalonate to Isopentenyl pyrophosphate <-> Dimethylallyl pyrophosphate |
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What is the rate limiting step in Step 1 of cholesterol synthesis |
HMG CoA is catalyzed by HMG CoA reductase This enzyme is blocked at high cholesterol levels and the cholesterol-lowering drugs "statin" and you do not form mevalonate |
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3 Uses of Acetyl CoA |
CAC Ketogenesis Cholesterol formation |
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Step 2 of cholesterol synthesis |
Formation of squalene Uses 6 isopentyl pyrophosphates to donate isoprenes |
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Where does cholesterol synthesis occur? |
In the liver |
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What does the liver use cholesterol for? |
Make Bile Make lipoproteins - Tissues take in LDL and release its components |
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Familial hypercholesteremia |
Inherited defect in LDL receptors Leads to an increase in circulating LDL and therefore an increase in cholesterol in the blood and increased risk of MI |
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What is the molecule used as a precursor to form steroids? |
Cholesterol |
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What is cholesterol converted to first? |
Progesterone and other steroid hormones form there. |
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Aldosterone |
Made in the adrenal cortex Promotes sodium reabsorption that leads to salt and water retention and increased BP |
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Cortisol |
Made in the adrenal cortex Stress hormone that promotes gluconeogenesis, glycogenolysis |
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Testosterone |
Some made in adrenal cortex but most is made in testes Responsible for male characteristics |
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Estrogen |
Some made in adrenal cortex - Most made in ovaries and placenta Responsible for female characterisitics |
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What are most plant steroids? |
Sterols |
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How can plants sterols be used therapeutically? |
Can mimic cholesterol in the intestine and partially block cholesterol absorption |
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Cardiac Glycosides |
Function to increase the force of contraction of the heart i.e. Digoxin (medicinal) Ouabain (toxic) |