metabolism bioenergetics

. Life is result of chemical interactions of various elements in the environment. Reactions in the living system occur due to

c. Interaction of electrons in the outer orbit of the atom.

1B.The most complex creation of nature, a human body is

c. A molecular assembly of mostly a few elements found in and on earth's atmosphere

2. In the following nuclear reaction, 4 protons fuse to make one He nuclei and 2 positrons.

H +H + H + H = He + 2e+ + Light and Heat

a. Is there an overall increase or decrease in entropy in this reaction?

à There is an overall increase in entropy because there is always an increase in entropy. We're converting mass to energy, which is largely favourable due to the fact that it's a large increase in disorder (due to thermodynamics' second law).

If there is an increase in entropy during this reaction, in what form it is occurring?

It looks like 4 Hydrogen atoms are making 1 Helium and 2 positrons and that is a decrease in the amount of atoms but that is why there is light and heat that is formed as well. By converting 4 H atoms to 1 He, there is a release of Energy and that is the biggest entropic change possible-mass to energy.

You measure energy during

• Heat change by measuring the temperature

• Light by measuring the wavelength (lower wavelengthàhigher E)

• Electricity by measuring the voltage (higher voltageà higher electricity)

• Free Energy change of a chemical reaction by measuring the concentration.

• Free energy change occurring during and Oxidation-reduction reaction by measuring voltage.

4. The original source of energy on this planet is

c. Nuclear energy

5. Second law of thermodynamics: Spontaneous reactions occur in a direction that increases the overall disorder in the system of universe or increases the entropy. Plants synthesize different compounds and create beautiful orders from disorder like flowers (e.g. Glucose from CO2, leaves, flowers, and fruits). Which of the following is true?

d. Disorder of energy is created in solar plasma

-> Plant takes CO2 from air, brings the molecules together and converts it into glucose

6. A child grows in a beautiful ordered way under proper nourishment.

Which of the following is true?

c. Disorder is created in the surroundings,

the Child is growing at the price of food and food is catabolized and disordered. You take in 6 molecules of glucose and that gets converted into 6 molecules of CO2 so increase in disorder. Child survived by burning fuel in the body.

-> Plants make the food at the price of solar energy.

7. Suppose you are running on the road for exercise. Write down the energy conversions from the source to the last form of energy in this process.

à First energy utilized is chemical energy in the form of food. The chemical energy in the food is converted into ATP.

Then ATP is utilized to move your muscles. The chemical energy in ATP is converted into kinetic energy. Now, hands and feet are moving.

Then kinetic energy is split where part is converted into sound, another part is generating heat because you're having friction with the air molecules and part of it could be converted into potential energy if your climbing up.

8. Which of the chemical group shown below is the best target for nucleophilic attack?

à The best target for nucleophilic attack is figure C because the carbon is bonded to oxygen by a double bond (which is the distinction between figure a and c) causing the electron density to be pulled towards the oxygen and resulting in carbon developing a partially positive charge (electron deficit). Electron density is pulled towards the oxygen because oxygen is the second most electronegative atom. The nucleophile can then attack the electron deficit carbon. The carbon in figure A is not as electron deficit as the carbon in figure C. The carbon in figure A is also bound to two hydrogen where between the two carbon is the boss (the more electronegative) and therefore pulls electron density towards itself, resulting in that carbon not being so partially positive.

9. Is burning of wood a favorable (spontaneous) reaction? If so, how and why?

- Yes it is spontaneous because there's an increase in entropy.

- Wood is a hydrocarbon, reduced carbon molecule, and oxygen is very electronegative atom and is very desperate to take the electrons from the wood. It is because of the high electronegativity of oxygen that it reacts violently and creates energy and an increase in entropy resulting in an

exergonic reaction. Sparking is called energy of activation so it is already given.

10A. Calculate the standard free energy change of the following reaction with the concentration of different ingredients at equilibrium are

A+B = C+D Concentration of A = 1M

B = 1M

C = 1M

D = 1M

Gas constant R = 8.3 J/mol.K

Absolute temp T = 298 K

à One divided by one = 1 and Ln. of 1 is 0 so delta G=-RT ln (conc) is going to be 0. So the reaction doesn't proceed in any direction.

10B. If A= 10 mM, B= 10 mM, D and C are 1M each.

-> Free energy= 11.4 kJ/mol (PAPER)

10C. A and b are 1M each, C and D are 10mM each

-> Free energy = -11.4 kJ/mol (PAPER)

12. Dr. Pandey's daily recommended energy requirement is 2000 Calories (8360 kJ). How much ATP (in grams) is hydrolyzed in one day by Dr. Pandey? Presume that free energy change in human physiological system is -50kJ/mole and molecular wt of ATP is approximately 500 Dalton.

à 8360kJ/50 kJ/mol = 16.7 mol x 500 Dalton = 83600 g so 83.6 kg

13. If the reaction product in any reaction is resonance stabilized i.e. if it has different electronic configurations for the same compound, the reaction proceeds spontaneously in forward direction. Give a thermodynamic explanation for this phenomenon.

-> Resonance stabilization always leads to more randomness i.e. increased entropy. Any reaction where there's an increase in entropy will be spontaneous and will proceed forward.

14. What would be the free energy change (DG) for a reaction that is at equilibrium

It would be 0. If the reaction is happening in the forward direction where the reactants are being converted into product, it is releasing energy. If it is happening in the backward direction, it needs energy. So free energy is either taken or given. But if at equilibrium, the rates of the forward and backward reactions are equal resulting in the free energy to be 0.

15. A flask containing boiling water is left on the desk. Water molecules in boiling water move at faster rate. After one hour, water cools down to room temperature. This is a spontaneous reaction. Explain entropy change in this reaction.

-> Entropy in the flask decreases because the movement of the water is slowed down. In the surroundings, entropy is increased; heat is released from the flask in the air causing air molecules to move faster. In the hot water in the flask, energy is kind of ordered in the form of solution and then heat is condensed in the water and is getting randomized.

16. Suppose the physiological concentrations of ATP, ADP and Pi are as follows in human liver cells;

ATP = 3.0 mM

ADP = 1.5 mM

Pi = 2.0 mM

How much free energy will be released during ATP hydrolysis of ATP in this condition?

-> Go' for ATP hydrolysis is -30.5 KJ/mole

18. Is the reaction in combustion engine favorable? If so, Why?

Yes this rxn is spontaneous bc the hydrocarbons readily react with O, and a lot of energy is released.

17. What is the difference in burning of cellulose (wood) in fire place and glucose burning in body?  In both reactions carbohydrate is converted to CO2.

Burning of cellulose is very explosive and a lot fo energy is lost as heat + light. Burning of glucose in the body is a step by step process where the energy is controlled and stored in ATP. 

Fe⁺⁺⁺ is involved in many redox reactions, it has different Standard reduction potential ranging from very positive to very negative. Explain why?

the standard reduction potential tells you how easily a species accepts electrons. The potential of Fe+++ strongly depends on its surroundings

20. Can you measure free energy of some reactions (happening at standard temp and pressure) without measuring concentrations? 

You can measure free energy at standard without measuring concentrations bc K is a fixed properly once known. But you can’t measure Delta G without concentrations bc that is about current state of the system.

21. What is the difference between Catabolism and anabolism. Which one is favorable reaction? 

Catabolism is the breakdown of molecules into smaller parts and anabolism is joining parts to make bigger molecules. Catabolism is favourable bc it releases energy.