Second Half F24II: Lecture Slides 32 - 57 Flashcards
What is Catabolism?
The breakdown of large molecules into simpler products
(Proteins, Lipids, Carbohydrates to CO2, H20, NH3)
What is Anabolism?
The building of larger molecules from simple precursors
(Sugars. Amino Acids, Fatty acids to Proteins, Lipids, Nucleic Acids)
What do catabolic pathways do?
They typically converge
What happens to the carbon “skeletons” of most sugars, fats and amino acids?
They are converted into a metabolite called Acetyl Coenzyme A (Acetyl CoA)
What can Acetyl CoA be used to build?
Everything from fatty acids to steroids to components of proteins and nucleic acids
What is a metabolic pathway?
A series of enzyme-catalyzed reactions
What does a metabolic pathways convert?
A precursor (A) into a product (E) through a series of intermediates known as metabolites
What does each step in a metabolic pathway bring?
A small but specific chemical change.
What does irreversible mean?
It contains on reaction that is thermodynamically very favourable
How are metabolic pathways regulated?
- Transcriptional control of enzyme levels
- Inhibition or activation of enzyme activity
What are the 3 ways of Elucidation of Metabolic Pathways?
1.) Metabolic Inhibitors
2.) Biochemical Genetics
3.) The use of Radioactive Labeled Substrates
What does the Use of Metabolic Inhibitors do?
When you inhibit an enzyme, you can isolate it and study it.
What can you study using Biochemical Genetics?
a. Genetic Diseases
b. The use of Auxotrophic Mutants
What can you do by studying auxotrophic mutants?
Identify the mutants by their requirement for the end product of the pathway and identify the metabolites that accumulate
What happens if a compound is synthesized with a 14C atom in it?
The compound, and any products derived from the 14C atom will be radioactive and is easily traceable.
How can a 14C be traced?
It releases a little flash of energy when it decays
What is an oxidation reaction?
The loss of electrons
What is a reduction reaction?
The gain of electrons
How do you figure out if B or A has a greater tendency to accept available e-?
Based on their Standard Reduction Potential (E0’) of the two half reactions
What is E0’?
The Standard Reduction Potential at pH 7 and 25 degrees celsius
What is SHE?
H2 -> 2H+ + 2e-
What is the E0’ of SHE?
-0.42 V
What can E0’ be used for?
To predict the direction of electron flow
What is the strength of the tendency proportional to?
Delta E0’
When can redox reaction proceed spontaneously?
IF Delta E0’ is greater than 0 (a positive number)
When will Gibbs free energy be spontaneous?
When it is negative
In redox reactions, what is the higher value?
Electron Acceptor (oxidizing agent)
What is the lower value?
Electron Donor (reducing agent)
What is △E0’ equal to (equation)
E0’(acceptor) - E0’(donor)
How do electrons always flow?
From a redox pair with lower E0’ to higher E0’
What is the equation for Gibbs Free Energy?
-nFE0’
What is Faradays Constant?
96.5 x 103 J/V mol
What can some enzymes use to carry out their functions?
1.) Inorganic Ions
2.) Coenzymes
What are inorganic Ions?
Mg2+, Zn2+, Fe2+, Mn2+, Cu2+
What are coenzymes?
Complex organic or metallooorganic compounds that act as transient carriers of specific functional groups.
What are many coenzymes derivates of?
Adenosine
What is ATP a carrier/donor of?
Many phosphate groups
What is ATP used for?
To phosphorylate many types of molecules such as sugars, lipids, proteins
What does phosphorylation do?
The addition of a phosphoryl (PO3) group to a molecule.
What is Phosphorylation important for?
In biological systems, this reaction is vital for the cellular storage and transfer of free energy using energy carrier molecules.
What is kinase?
A family of enzymes that phosphorylate molecules with the help of ATP
What is CoA a carrier of?
Acid groups
What is CoA derived from?
Pantothenic Acid
What are the groups found in CoA
B-mercaptoethylamine, pantothenic acid, adenosine
What happens when CoA is mixed with organic acids?
Forms thioester derivatives
What is a thioester?
Sulfur analogue of an ester (O has been replaced by an S)
What is a coenzyme A thioester derivative called?
An acyl CoA
In the case of acetic acid, what is the corresponding Acetyl CoA derivative called?
Acetyl CoA
What are NAD+, NADP+, FAD and FMN involved in?
The electrons that are removed from the substrates are transferred on to these cofactors reducing them and conserving the energy of oxidation
What are the cofactors NAD+ and FAD involved in?
Beta Oxidation
What type of nucleotide are NAD and NADP?
Pyrimidine Nucleotides (single ring)
What are NAD and NADP derived from?
The vitamin niacin (B3)
What does the structure of NAD and NADP consist of?
Niacin (nicotinamide ring) and Adenosine
Where do redox reactions occur - NAD and NADP?
At the nicotinamide ring
What happens during oxidation of substrates?
Two hydrogen atoms are removed from the substrate
What does the oxidized form of NAD and NADP accept?
A hydride (H-) ion - equivalent of a proton and two electrons
What does the hydride ion make NAD and NADP?
Reduced to become NADH and NADPH
Where is the other proton released?
Into the environment
What is NAD+ used as?
The oxidizing agent in fatty acid oxidation, TCA cycle
- The resulting NADH is reoxidizes via ETC to generate energy
What is NADPH used as?
The reducing agent (losing electrons) in biosynthesis
What are FAD and FAM?
The flavin nucleotides
What vitamin. are FAD and FAM derivates of
Riboflavin (B2) vitamin
What do Flavin Nucleotides act as?
Prosthetic groups (tightly bound to the enzyme helping out)
What is the structure of FAD?
Adenosine and Vitamin B2 (riboflavin)
What is the structure of FMN?
Monophosphate group and a riboflavin B2 vitamin
What can flavin nucleotides accept?
One or two electrons (in the form of one or two hydrogen atoms) from substrates undergoing oxidation
What are the fully reduced forms of the nucleotides FAD and FMP?
FADH2 and FMNH2
What happens when only one electron is accepted?
They form the stable semiquinone radical DADH and FMNH
Due to the ability for FMN and FAD to participate in either one or two electron transfers, what are they involved in?
A greater diversity of reactions than the NAD(P) linked dehydrogenases
