Second Half F24 II: Lecture Slides 58 - 79 Flashcards
How much energy does Protein give off?
17 kJ
How much energy does a Carbohydrate give off?
16kJ
How much energy does a Fat give off?
37 kJ
What is the most concentrated store of metabolic energy?
Fat
What does it mean when a molecule is very reduced?
It has gained electrons and become more negative
Why is fat considered to be the most concentrated store of metabolic energy?
Fat is chemically very reduced - most of its carbons are found in the form CH2.
What does the fat being in its reduced form cause?
When it is oxidized to CO2, it releases the maximum amount of energy.
Why does sugars not release a large concentration of energy?
The C in the sugar are found in its CH2O form, meaning they are already partially oxidized.
Why can fat be stored water-free?
Due to its hydrophobic properties
What is the general rule for a molecule to be the most oxidized?
If it has less hydrogen and more oxygen it is in its oxidized state
What molecule is the most oxidized form of carbon found in living systems?
Carbon Dioxide
Consider the following four compounds are oxidized to CO2
i. CH3-CH3
ii. CH3CHO
iii. CH3CH2OH
iv. CH3COOH
What is the relative quantities of the greatest free energy released?
i > iii > ii > iv
What is the human fuel reserve for glucose?
150 kJ
What is the human fuel reserve for glycogen?
2,500 kJ
What is the protein human fuel reserve?
100,000 kJ
What is the fat human fuel reserve?
500,000kJ
What are Fatty Acids found mainly in?
Triacyclglycerols (TAGs)
What can TAGS be converted into with the help of lipase (breaks the ester linkage)?
Fatty Acids (Beta Oxidation) or Glycerols (for glycolytic intermediate)
What are the three steps of the complete oxidation of a Fatty Acid to CO2 and H20?
1.) Beta Oxidation
2.) Krebs cycle (Citric Acid Cycle)
3.) ETC
What does Beta Oxidation give rise to?
Acetyl CoA and Reduced Cofactors (NAD, FAD, etc)
What did Franz Knoop discover?
He tagged the omega carbon of even and odd chained fatty acids to determine their aromatic products
What was the aromatic product of the odd number of carbons?
Benzoic Acid
What was the aromatic product of the even number of carbons?
Phenylacetic Acid
What was Franz Knoops conclusion?
That the Fatty Acids were catabolized at two carbons at a time
How are Fatty Acids prepared for catabolism?
By activating them into fatty acyl CoA
What does a Fatty Acid + CoA + ATP produce with the help of Acyl-CoA synthetase produce?
Fattyl Acyl CoA + AMP + PPi
Delta G = -15kJ/mol
What can the PPi be further broken down into?
2Pi
Delta G = -19kJ
What is the overall activated reaction of a Catabolism of a Fatty Acid?
Fatty Acid + ATP + CoA —-> Fatty Acyl CoA + AMP + 2Pi
Where does Acyl CoA synthetase occur?
Outer Mitochondrial Membrane
What is Synthetase?
An enzyme that combines two small molecules to form a larger molecule with the help of ATP
What is Synthase?
An enzyme that combines two small molecules to form a larger molecule with NO help of ATP
What is the First Step of Fatty Acid Activation?
The nucleophilic oxygen of the Fatty Acid attacks the alpha phosphate of the ATP (the electrophile) forming PPi and an acyl adenylate.
- The PPI is immediately converted to 2Pi
What is the Second Step of Fatty Acid Activation?
The thiolate anion form of coenzyme A, as the nucleophile reacts with the acyl adenylate. AMP is the leaving group and the fatty acyl-CoA thioester is formed
What is the total energy formed from the attachment of a Fatty Acid to CoA?
-34 kJ
Where does B-oxidation take place?
Mitochondrial Matrix
What is the Outer Mitochondrial Matrix’s permeability?
Freely permeable to small molecules and ions
What is the Inner Mitochrondrial Matrix’s permeability?
Highly impermeable to solutes
What is the chemical composition of the Mitochondrial Matrix like?
Differs immensely compared to the cytoplasm
Where does the activated fatty acid reaction take place?
In the cytoplasm
Where does the Activated Fatty Acyl CoA need to go to?
The Mitochondrial Matrix
How are Fatty Acids transported not the Mitochondrial Matrix?
Via the Acyl-Carnitine Transporter in the form of Acyl-Carnitine Esters
Describe the Steps of the Acyl-Carnitine Transport?
The Acyl CoA Fatty Acid combines with cartinine to form acyl cartinine, where it can enter into the outermitochondrial membrane to the intermebrane space, to the inner mitochondrial membrane and then into the matrix where it can undergo Beta Oxidation
What is special about the cartinine molecule?
It is able to go back again and pick up another acyl-CoA fatty acid
What are the Four Steps of Beta Oxidation?
1.) Oxidation
2.) Hydration
3.) Oxidation
4.) Thiolysis
What does each pass through Beta Oxidation Cause?
The removal of one acetyl moiety in the form of acetyl CoA
What is the first step of Beta Oxidation?
Oxidation by FAD forms a double bond between the alpha and beta carbons of fatty acyl CoA resulting in a trans enoyl-CoA
What does FAD become?
It becomes FADH2 (more positive, lost electrons)
What is the Second Step fo Beta Oxidation?
Water is added across the double bond to give an alcohol at the Beta Carbon (alkene to an alcohol) resulting in a B-hydroxyacyl-CoA
What is the Third Step of Beta Oxidation?
Oxidation of the Alcohol by NAD+ to give Ketoacyl-CoA
What is the Fourth Step of Beta Oxidation?
Lysis of the bond between the alpha and B carbons (Thiolysis)
What is a Thiolysis?
A thiol analogue of a hydrolysis
What does each round for Beta Oxidation produce?
Produces an acetyl CoA and shortens the chain by two carbons (Beta Oxidation continues until all of the carbons are released as acetyl CoA’s)
For instance, say you have a 16C Fatty Acyl CoA, how many rounds of Beta oxidation will take place and how many CoA will be produced?
7 rounds of Beta Oxidation (7 NAD, 7H2O, 7FAD,etc.) will happen and 8 Acetyl CoA will be produced
Where does the Acetyl-CoA enter into?
The Citric Acid Cycle
