Chapter 15: Metabolism Basic Concepts and Design Flashcards
Adenosine Triphosphate (ATP)
The energy currency of the cell. We want to make this.
Why is hydrolysis of ATP so favorable?
1.) Resonance Stability. The reactants (ATP) has three resonance structures while the products (ADP and free phosphate) have seven resonance structures. More resonance=more stability.
2.) Entropy increases. The hydrolysis of ATP is accomplished in H2O and this is 55.6M so we consider this essentially constant. By doing this entropy is increased by forming ADP and free phosphate.
3.) Electrostatic Repulsion. When in the form of ADP and free phosphate the negative charge on the terminal phosphate is now further away from the other negative charges which is more favorable.
4.) Hydration of products. There is hydrogen bonding occurring since this reaction is in water so because there are more products, there is more hydrogen bonding which means it is inhibited from going in the reverse back to ATP so the hydrolysis is more favorable.
Phosphoryl-transfer potential
They are high energy bonds that when broken release a lot of free energy. So the higher the potential the higher amount of free energy released. ATP is a middle phosphoryl-transfer potential.
Activated carrier
ATP is an activated carrier because it brings the phosphate group that will activate other reactions to occur.
Vitamin
Organic molecules that are needed in small amounts in the diets of some higher animals.
Oxidation-Reduction reaction
Useful energy is derived from the oxidation of carbon compounds. Oxidation=less hydrogens bound to the carbon. Reduction=more hydrogens bound to the carbon.
Group transfer reaction
One group is moved from one compound to another. Glucose to Glucose-6-phosphate is an example.
Hydrolytic reaction
Cleave bonds by the addition of water.
Cleavage of carbon bonds other than by hydrolysis or oxidation
Lyases can catalyze the reaction of going from one molecule to two smaller molecules.
isomerization reaction
rearrange particular atoms within a molecule. Citrate to isocitrate is an example.
Ligation reaction
form bonds by using free energy from ATP cleavage. Pyruvate to oxaloacetate is an example.
Phosphorylation potential
Depends on the concentration of free phosphate and is directly related to the free-energy storage available from ATP. ATP/ADP+Pi
How are deltaG and Keq related?
When Q=Keq, deltaG=0
When Q>Keq, (will go in the reverse direction)
When Q<Keq, (will go in the forward direction)
What is the difference between deltaG^o and deltaG^o’?
-DeltaG^o is the standard state which means that the concentration is 1M or if it is a gas it is at 1atm. This will cause the conc of hydronium ion to be 1M which gives a pH of 0 which is too acidic and wont work in the body. (Denaturation)
-DeltaG^o’ is the standard state biochemically. This means that the conc of the hydronium ion will be 1.0x10^-7 and the conc of H2O is 55.6M. The pH will therefore be 7 or neutral which will work in the body.
How are coupled reactions useful?
A coupled reaction involves an unfavorable reaction that is coupled with a favorable reaction. This is beneficial because the reaction that was once unfavorable can now become favorable after coupling with an already favorable reaction.
