Chapter 7 - Energy And Metabolism Flashcards
Matter
Anything that has mass and takes up space
Energy
The capacity to do work, which is any change in the state or motion of matter.
Can be measured as heat energy, thermal energy that glows from an object with a higher temperature to an object with a lower temperature.
The unit of heat energy is kilocalorie (kcal), which is equal to 4.184 kJ.
Heat energy-kilocalories (kcal)
Thermal energy that flows from an object with a higher temperature to an object with a lower temperature.
Kinetic energy
The energy of motion. Eg. an archer draws a bow.
Potential energy
Stored energy. (Tension in the bow and string represent stored(potential) energy.
Closed system
Doesn’t exchange energy with its surroundings
Open system
Can exchange energy with its surroundings
ATP (Adenosine Triphosphate)
A nucleotide that consist of adenine(a nitrogen containing base), ribose(a 5 carbon sugar), and 3 phosphate groups.
ADP + Pi + energy = ATP
ADP (Adenosine diphosphate)
The hydrolysis of ATP yields ADP and inorganic phosphate(Pi). ADP consists of adenine, ribose and phosphate groups, one of which is inorganic phosphate.
AMP + Pi + energy = ADP
Phosphorylation
A reaction in which a phosphate group is transferred to some other compound.
Oxidation
Substance that becomes oxidized gives up energy
A loss of electron
A gain of oxygen
A loss of H
An increase in oxidation number
Reduction
Gain an electron(gain energy)
Loss of oxygen
Gaining of H
A reduction in oxidation number
Redox
Oxidation and reduction occur simultaneously.
The oxidized substance gives up energy as it releases electrons.
The reduced substance receives energy as it gains electrons. Redox reactions usually involve a transfer of hydrogen atom rather than just an electron.
XH2 + NAD+ ➡️ X + NADH + H+
Oxidized. Reduced
Enzymes
Biological catalyst that increase the speed of a chemical reaction without being consumed by the reaction.
Lower activation energy
Very sensitive to temperature, pH, Concentration, Inhibitors.
Increase temp above optimum-denature enzyme
Decrease- it will slow down the reaction but will not denature the enzyme
Catalase
Enzyme that decompose molecules of hydrogen
Activation Energy(Energy of activation Ea)
The energy required to break the existing bonds and begin the reaction.
Substrate
The substance on which an enzyme acts.
They attach to active site.
Enzyme-Substrate complex(ES complex)
When ES complex breaks up, the product is released; the original enzyme molecule is regenerated and is great to form a new ES complex:
Enzyme + substrate ➡️ ES complex
ES complex ➡️ enzyme + products
Enzymes can be reused
Coenzyme
Non polypeptide organic molecule that binds to the apoenzyme( a protein) and serves as a cofactor( additional chemical component).
Buffers
Minimize pH changes in cells so that pH is maintained within a narrow limit.
First law of thermodynamics
Energy cannot be created or destroyed but can be transferred and changed in form.
Second law of thermodynamics
Disorder (Entropy) in the universe, a closed system, is continuously increasing.
No energy transfer is 100% efficient; some energy is dissipated as heat, random motion that contributes to entropy (S), or disorder.
Exergonic
Spontaneous reaction
releases free energy that can perform work.
Has a negative value of 🔼G
Endergonic
Non spontaneous
Requires additional energy
Has a positive value of🔼G
Coupled reaction
The input of free energy required to drive an endergonic reaction is supplied by an exergonic reaction.
Enzyme inhibitors
Molecules that interact in some way with the enzyme to prevent it from working in a normal manner.
Many drugs are enzyme inhibitors.
Competitive inhibitors
Compete with the substrate for access to active site of the enzyme.
Non competitive inhibitors
Binds outside the active site of the enzyme.
Allosteric site - binding causes conformational change in enzyme active site inhibiting enzyme function.
Feedback inhibition - product of pathway inhibits early steps to prevent over accumulation of product.
Anabolism
Complex molecules synthesized from simpler substances
Catabolism
Larger molecules broken down into smaller ones
