Seminar 7: Intro to Energy

Question 1

first law of thermodynamics?

Answer 1

energy cannot be created/destroyed only transferred/transformed

Question 2

second law of thermodynamics?

Answer 2

energy transformations increase the entropy (disorder) of the universe

Question 3

different forms of energy & e.x

Answer 3

1. chemical: bond energy
2. heat:
3. light:
   4: kinetic:
4. electrical:

Question 4

what are the 2 classifications of energy

Answer 4

kinetic & potential

Question 5

what is the diff b/w kinetic & potential energy?

Answer 5

1. kinetic is energy of movement, it does work, makes things (heat, light)
2. potential is energy of state/position, it is stored (chemical, electrical)

Question 6

why is ATP an energy rich molecule

Answer 6

• the terminal phosphates are both -ve & therefore repel each other greatly
• thus a lot of energy is required to form the bond b/w them
• when ATP is hydrolysed, the breakage of the terminal bond releases A LOT of energy

Question 7

Describe the ATP cycle: How is ATP used and regenerated in a cell?

Answer 7

• free energy released from the hydrolysis of ATP may drive reactions through the transfer of a phosphate group to a reactant molecule
• this forms a more reactive phosphorylated intermediate
• ATP hydrolysis also powers the mechanical & transport work of a cell, often powering shape changes in the relevant motor proteins
• Cellular respiration, the catabolic breakdown of glucose, provides the energy for the endergonic regeneration of ATP from ADP & Pi.

Question 8

How does ATP typically transfer energy from an exergonic to an endergonic reaction in the cell?

Answer 8

ATP usually transfers energy to an endergonic process by phosphorylating another molecule. (Exergonic process, in turn, phosphorylate ADP to regenerate ATP).

Question 9

what are exergonic & endogonic reactions?

Answer 9

1. exergonic releases energy (catabolic, cellular respiration)
2. endogenic consumes energy (anabolic, photosynthesis, active transport)

Question 10

differentiate b/w spontaneous & non spontaneous reactions

Answer 10

spontaneous occur w/o any energy input, non-spontaneous don’t

Question 11

meaning of delta G values

Answer 11

delta G = free energy of products - free energy of reactants
-ve delta G = free energy released in reaction (exergonic)
+ve delta G = free energy required for reaction (endogenic)

Question 12

what does delta G tell us abt a system?

Answer 12

stability
- more free energy (-ve) = less stable & greater work capacity
- less free energy (+ve) = more stable & less work capacity