Term
| Give two reasons why fatty acids are used as energy storage. |
|
Definition
1. Fatty acids are reduced, so their oxidation yields the most energy possible.
2. Fatty acids are not hydrated, and can therefore be packed more efficiently. |
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Term
| _________ are the major form of stored energy in the body. |
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Definition
|
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Term
| Describe the general process by which hormones trigger the release of fatty acids from triglycerides. |
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Definition
| Hormones bind to a receptor, causing the activation of adenyl cyclase. cAMP then stimulates a protein kinase cascade. These kinases activate triacylglycerol (TAG) lipase by phosphorylation. TAG lipase then promotes the release of fatty acids from TAGs. |
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Term
| Dietary TAGs are released in the __________. |
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Definition
| duodenum (first portion of the small intestine) |
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Term
| __________ require bile salts that emulsify TAGs. |
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Definition
|
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Term
| ____________ are carboxylic acid salts with hormone backbones. |
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Definition
|
|
Term
| __________ are lipoprotein aggregates that are assembled in the intestinal wall. |
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Definition
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Term
| In the small intestine, fatty acids combine with bile salts in _____________ which deliver fatty acids to epithelial cells that cover the intestinal villi. |
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Definition
|
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Term
| Fatty acids are degraded by repeated cycles of _________. |
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Definition
|
|
Term
| Beta oxidation converts fatty acids into ____________. |
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Definition
| acetate units (acetyl-CoA) |
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Term
| ____________ condenses fatty acids with CoA, with simultaneous hydrolysis of ATP to AMP and PPi. |
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Definition
|
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Term
| True or False: The acyl-CoA synthetase reaction is energetically driven by the hydrolysis of pyrophosphate. |
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Definition
|
|
Term
| Beta oxidation occurs in the ______. |
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Definition
|
|
Term
| True or False: Long-chain fatty acids can be directly transported across the mitochondrial membrane. |
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Definition
|
|
Term
| ____________ are fatty acyl transporters. |
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Definition
|
|
Term
| _____________ can be shuttled across the membrane by an acyl translocase. |
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Definition
|
|
Term
| In general terms, list the steps of beta oxidation. (E.g. hydration, oxidation, etc.) |
|
Definition
1. Oxidation
2. Hydration
3. Oxidation
4. Cleavage
5. Rinse and repeat |
|
|
Term
| Describe the first step of beta oxidation including reactant, enzyme, cofactors and product. |
|
Definition
| Fatty acyl-CoA --> trans-enoyl-CoA by acyl-coa dehydrogenase and reduction of FAD |
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|
Term
| Describe the second step of beta oxidation, including reactant, enzyme, cofactor and product names. |
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Definition
| trans-enoyl-coa --> beta-hydroxyacyl-CoA by enoyl-coa hydratase and addition of H2O |
|
|
Term
| Describe the third step of beta oxidation, including reactant, enzyme, cofactor and product names. |
|
Definition
| beta-hydroxyacyl-CoA --> beta-ketoacyl-CoA by hydroxyacyl-CoA dehydrogenase and NAD reduction |
|
|
Term
| Describe the fourth and final step of beta oxidation, including reactant, enzyme, cofactor and product names. |
|
Definition
| beta-ketoacyl-CoA --> shorter fatty acyl-CoA by thiolase and CoASH (causes release of acetyl-CoA) |
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|
Term
| By how much does one cycle of beta-oxidation shorten a fatty acyl-CoA? |
|
Definition
|
|
Term
| True or False: VLCAD are membrane bound enzymes while LCAD, MCAD and SCAD are families of soluble enzymes. |
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Definition
|
|
Term
| True or False: The two electrons removed during the beta oxidation cycle are delivered to the electron-transport chain in the form of reduced coenzyme Q (UQH2). |
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Definition
|
|
Term
| Enoyl-CoA Dehydrogenase is also called __________. |
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Definition
|
|
Term
| Complete beta-oxidation of palmitic acid yields how many ATPs? |
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Definition
|
|
Term
| Large amounts of ______ is produced by beta-oxidation of fatty acids, which helps animals survive in arid conditions. |
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Definition
|
|
Term
| Slow-twitch muscles are _________. |
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Definition
|
|
Term
| Fast-twitch muscles are __________. |
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Definition
|
|
Term
| Beta-oxidation of odd-carbon fatty acids yields _____________. |
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Definition
|
|
Term
| True or False: A complex of four enzymes converts propionyl-CoA into succinyl-CoA. |
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Definition
|
|
Term
| Succyinyl-CoA can be converted into _______ for transportation into the cytosol. |
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Definition
|
|
Term
| Polyphenolic compounds found in chocolate, green tea and red wine are called ____________. |
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Definition
|
|
Term
| __________ converts cis-acyl-CoA into trans-acyl-CoA so that it can be used by acyl-CoA dehydrogenase. |
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Definition
|
|
Term
| _______________ converts trans-cis structures into a trans unsaturated fat. |
|
Definition
| 2,4-Dienoyl-CoA reductase |
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|
Term
| Branched fatty acids are degraded via ____________ oxidation. |
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Definition
|
|
Term
| Name the three types of ketone bodies. |
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Definition
| Acetone, acetoacetate and beta-hydroxybutyrate |
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|
Term
| Synthesis of ketone bodies occurs in ________. |
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Definition
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|
Term
| True or False: Diabetics have an overabundance of glycolysis, which depletes their oxaloacetate levels, causing fat catabolism to go to ketone bodies rather than the TCA cycle. |
|
Definition
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Term
| List the four major differences between the lipid catabolic and biosynthetic pathways. |
|
Definition
1. In biosynth, lipids are linked to acyl carriers, as opposed to CoA.
2. Synth occurs in the cytosol instead of mitochondria.
3. Enzymes for synth are one polypeptide, the fatty acid synthase
4. Biosynth uses NADPH, while breakdown uses NADH |
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|
Term
| The addition of two-carbon units to the growing fatty acid chains are driven by the decarboxylation of _____________. |
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Definition
|
|
Term
| True or False: Elongation reactions are repeated until the chain reaches 18 carbons in length. |
|
Definition
| False: 16 carbon (palmitic acid) |
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|
Term
|
Definition
|
|
Term
| Three sources of acetyl-CoA in the cytosol |
|
Definition
1. amino acid degradation
2. fatty acid oxidation
3. glycolysis (main source) |
|
|
Term
| Study the following diagram carefully. DO IT. |
|
Definition
 |
Term
| True or False: The carboxylation of acetyl-CoA to form malonyl-CoA is the committed step in fatty acid biosynthesis. |
|
Definition
|
|
Term
| Acetyl-CoA carboxylase uses what three cofactors? |
|
Definition
| ATP, biotin and bicarbonate |
|
|
Term
| Name the three protein components of ACC. |
|
Definition
1. biotin carboxyl carrier protein
2. biotin carboxylase
3. carboxyltransferase |
|
|
Term
| True or False: ACC is carefully regulated, being inhibited by citrate and activated by palmitoyl-CoA. |
|
Definition
| False: citrate favors active polymer while palmitoyl-CoA favors monomeric form |
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|
Term
| True or False: Phosphorylated acetyl-CoA carboxylase is activated only by high levels of citrate, but is inhibited by low levels of palmitoyl-CoA. |
|
Definition
| True. The inverse holds true for its dephospho-form |
|
|
Term
| ___________ carry the intermediates in fatty acid synthesis. |
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Definition
|
|
Term
| True or False: In mammmals, fatty acid synthesis takes place in multienzyme complexes called fatty acid synthase II (FASII). |
|
Definition
| False; FASII is present in plants and bacteria. FASI is in mammals. |
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|
Term
| True or False: When introducing double bonds into fatty acid chains, eukaryotes use an oxygen-dependent process. |
|
Definition
|
|
Term
| __________ is the precursor to omega-3 fatty acids. |
|
Definition
|
|
Term
| _____________ is the precursor to omega-6 fatty acids. |
|
Definition
|
|
Term
| Omega-3 fatty acids are precursors to _________. |
|
Definition
|
|
Term
| ________ activates ACC/inhibits lipases. |
|
Definition
|
|
Term
| ___________ inhibits ACC/activates lipases. |
|
Definition
|
|
Term
| Fatty acyl-CoAs (activates or inhibits?) acetyl-CoA carboxylase. |
|
Definition
|
|
Term
| Citrate (activates or inhibits?) acetyl-CoA carboxylase. |
|
Definition
|
|
Term
| Malonyl-CoA blocks _______, thereby inhibiting beta-oxidation. |
|
Definition
| carnitine acyltransferase |
|
|
Term
| Study the following image carefully. DO IT. |
|
Definition
 |
Term
| Study the following image carefully. DO IT. |
|
Definition
 |
Term
| True or False: COX-1 is a common action site of many anti-inflammatory medications. |
|
Definition
|
|
Term
| Where is the primary site of cholesterol synthesis in the body? |
|
Definition
|
|
Term
| The cholesterol biosynthetic pathway begins with the synthesis of ____________. |
|
Definition
|
|
Term
_________ is a precursor to bile salts and steroid hormones.
|
|
Definition
Cholesterol
|
Term
| ___________ is the rate-limiting step in cholesterol synthesis. |
|
Definition
|
|
Term
| In general terms, what is the process of cholesterol synthesis? |
|
Definition
1. Thiolase reaction converts acetyl-CoA into acetoacetyl-CoA
2. HMG-CoA is formed
3. HMG-CoA is converted to mavelonate using two NADPH |
|
|
Term
| What are the 3 mechanisms that regulate HMG-CoA reductase? |
|
Definition
1. reversible phosphorylation
2. short half-life (degradation)
3. gene expression |
|
|
Term
| True or False: Statins lower serum cholesterol levels. |
|
Definition
|
|
Term
| ______________ is a cluster of lipids with an apolipoprotein. |
|
Definition
|
|
Term
Name a few lipoprotein types.
|
|
Definition
| LDL, VLDL, HDL, chylomicrons |
|
|
Term
| Lipoproteins are classified according to what? |
|
Definition
|
|
Term
| True or False: Lipoprotein lipases hydrolyze triglycerides from lipoproteins in the capillaries and tissues to make them smaller and increasing their density. |
|
Definition
|
|
Term
| ________________ is the term given to a variety of inherited metabolic defects that lead to greatly elevated levels of serum cholesterol |
|
Definition
| familial hypercholesterolemia |
|
|
Term
| ____________ is the branch point for either sex hormone or corticosteroid production. |
|
Definition
|
|
Term
| True or False: Ketone bodies are formed from Acetyl-CoA in an ATP dependent reaction. |
|
Definition
|
|
Term
| True or False: In mammals, fatty acid synthesis normally occurs in the mitochondria. |
|
Definition
|
|
Term
Which lipid form is transported across the inner mitochondrial membrane before beta-oxidation?
a. fatty acyl CoA
b. acetoacetyl CoA
c. o-acylcarnitine
d. L-carnitine |
|
Definition
|
|
Term
| Elevated levels of the 1st messenger ______ stimulates the conversion of TAGs stored in adipose cells to free fatty acids. This signal also results in phosphoylation of ACC, which inhibits fatty acid synthesis unless citrate levels are very high. |
|
Definition
|
|
Term
Which of the following enzymes delivers NADH to the electron transport system?
a. acyl-CoA dehydrogenase
b. hydroxyacyl-CoA dehydrogenase
c. thiolase
d. enoyl-CoA hydratase |
|
Definition
| B. hydroxyacyl-coa dehydrogenase |
|
|
Term
| True or False: Malonyl-CoA is not required for fatty acid synthesis since it can easily be made from Acetyl-CoA. |
|
Definition
|
|
Term
| Beta-oxidation of odd-carbon fatty acids yields ___________. |
|
Definition
|
|
Term
| How is (glucose derived) acetyl-CoA made available for fatty acid biosynthesis? |
|
Definition
| Glucose is converted into pyruvate via glycolysis in the cytosol. Pyruvate is then translocated to the mito matrix and converted to either OAA or acetyl-CoA, condensed as citrate, and transported back out to the cytosol. From there, it can be converted back into OAA and acetyl-CoA and used for fatty acid synth. Malate can also be used in the shuttle allowing all pyruvate to be converted to acetyl-CoA. |
|
|
Term
WHich of the following is the primary regulation step of fatty acid synthesis?
a. transportation of mitochondrial acetyl coa to the cytosol
b. carboxylation of the acetyl coa to form malonyl coa
c. assembly of the fatty acid chain
d. none of the above |
|
Definition
| b. formation of malonyl coa |
|
|
Term
Each of the following is a hormonal regulator of fatty acid metabolism, except:
a. glucagon
b. epinephrine
c. insulin
d. none are regulators
e. all are regulators |
|
Definition
|
|
Term
Which of the following blocks carnitine acyltransferase and thus inhibits beta-oxidation during lipid biosynthesis?
a. citrate
b. glucagon
c. insulin
d. malonyl-coa |
|
Definition
|
|
Term
| True or False: The phosphorylation of acetyl-CoA carboxylase regulates enzyme activity by introducing conformational changes within the protein that favor enzyme activity. |
|
Definition
|
|
Term
| Malonyl-CoA-acetyl-CoA-ACP transacylase (MAT) transfers the malonyl group of malonyl-CoA to ____________. |
|
Definition
| acyl carrier protein (ACP) |
|
|
Term
| What is the product of fatty acid synthesis? |
|
Definition
|
|
Term
| True or FAlse: HMG-CoA reductase is the rate limiting step in cholesterol biosynthesis, and also the site of action of cholesterol reducing drugs. |
|
Definition
|
|
Term
| True or FAlse: The main function of LDL is to transport cholesterol to tissues. |
|
Definition
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