Beta oxidation

Question 1

why are fats the most concentrated store of metabolic energy

Answer 1

• it is chemically very reduced, releases max amount of free energy when oxidized all the way to CO2
• very hydrophobic and can be stored nearly water free

Question 2

steps in the complete oxidation of fatty acids to CO2 and H2O

Answer 2

1. Beta oxidation: gives rise to acetyl-CoA and reduced cofactors
2. the citric acid cycle (oxidizes CO2)
3. the electron transport chain (oxidize NADH and FADH2)

Question 3

who identified beta oxidation

Answer 3

Franz Knoop

Question 4

discovery about fatty acid catabolism

Answer 4

fatty acids are catabolized 2 carbons at a time

Question 5

how are fatty acids prepared for catabolism

Answer 5

• activating them to fatty acyl CoA
• Acyl CoA synthetase occurs in the outer mitochondrial membrane

Question 6

fatty acid activation

Answer 6

1. nucleophilic oxygen of the fatty acid attacks the alpha phosphate of ATP forming PPi (immediately hydrolyzed to 2Pi) and acyl adenylate
2. the nucleophilic thiolate anion form of CoASH reacts with acyl adenylate. AMP is the leaving group, fatty acyl-CoA thioester is formed

Question 7

synthetase

Answer 7

• enzyme that combines 2 small molecules to form a larger molecule with the help of ATP energy

Question 8

synthase

Answer 8

• enzyme that combines 2 small molecules to form a larger molecule
• DOES NOT require ATP

Question 9

mitochondrial matrix

Answer 9

• where beta-oxidation happens
• outer membrane is freely permeable to small molecules
• inner membrane is highly impermeable to most solutes

Question 10

acyl-carnitine / carnitine transporter

Answer 10

• transports fatty acids with > 12 carbons into the mitochondria
• found in the form of fatty acyl-carnitine esters

Question 11

Beta-oxidation pathway

Answer 11

1. oxidation
2. hydration
3. oxidation
4. thiolysis
   - each pass through the cycle produces an acetyl CoA and shortens the chain by 2 carbons

Question 12

B-O Step 1: oxidation by FAD

Answer 12

forms a double bond between a and B carbons of fatty acyl coA
- becomes trans-delta2-enoyl-CoA
- creates a double bond
- enzyme: acyl-CoA dehydrogenase

Question 13

B-O step 2: hydration

Answer 13

• water is added across the double bond to give an alcohol at the beta carbon
• product is L-B-hydroxy-acyl-CoA
• enzyme: enoyl-CoA hydratase

Question 14

B-O step 3: oxidation by NAD+

Answer 14

• produces B-Ketoacyl-CoA
• enzyme: B-hydroxyacyl-CoA dehydrogenase

Question 15

B-O step 4: thiolysis

Answer 15

• breaks bond between a and B carbons
• produces acetyl-CoA
• enzyme: thiolase

Question 16

when is beta-oxidation repeated until

Answer 16

• once all carbon atoms in the chain are released as acetyl CoA
• complete oxidation of palmitic acid produces 8 molecules of acetyl CoA
• 1 FADH2 is formed per turn (7 total)
• 1 NADH is formed per turn (7 total)

Question 17

what is carnitine used for

Answer 17

to deliver triacylglycerols from the intestine to tissues via the bloodstream

Question 18

Acyl-CoA synthetase

Answer 18

activates fatty acids for oxidation
- occurs in the mitochondrial membrane
- Combines fatty acid and CoA with help of ATP

Question 19

what is true of the oxidation of 1 mole of palmitate

Answer 19

• activation of the free fatty acid requires the equivalent of 2 ATP
• inorganic phosphate (PPi) is produced
• 8 mol of acetyl-CoA are formed