Ch. 6 - Energy and Metabolism Flashcards
What is energy?
The capacity to do work?
What is work?
Force x Distance
What are two kinds of energy?
1) Kinetic energy
2) Potential energy
What is Kinetic energy?
Give an example.
The energy of motion
A boulder rolling down a cliff.
What is potential energy?
Give an example.
Stored energy.
A boulder on the edge of a cliff.
What forms can energy take?
- Mechanical
- Heat
- Sound
- Light
- Chemical
- Radioactivity
Why is heat a good way to measure energy?
Because all form of energy can be converted to heat.
What is thermodynamics?
The study of energy.
What is heat?
The energy derived from the random motion of molecules.
What is the unit of heat used in biology?
The kilocalorie.
How many calories are in 1 kilocalorie?
1000 calories.
What is a calorie?
The amount of heat required to raise one gram of water 1 degree Celsius.
What is a unit of energy that is used in physics?
Joule.
What happens to a molecule during oxidation?
A molecule loses an electron.
What happens when a molecule is reduced?
A molecule gains an electron.
What are redox reactions?
The pairing of oxidation/reduction reactions; they always occur together.
What do the laws of thermodynamics explain?
How energy changes occur in the universe.
How many laws of thermodynamics are there?
What are they?
2
1st law of thermodynamics
-Energy cannot be created or destroyed, it can only be changed from one form to another.
2nd law of thermodynamics
-The entropy in the universe is always increasing.
What is entropy?
A measure of disorder; as energy is used, more and more of it changes to heat.
What increases and decreases entropy?
Chemical bonds reduces.
Heat energy increases.
What is free energy?
The amount of energy that is available to do work.
What changes the amount free energy in a cell?
Chemical reactions.
What determines the free energy in a cell?
Depends on heat and chemical energy.
What are endergonic reactions?
Reactions that require energy to start.
What are exergonic reactions?
Reactions that increase in entropy of the system and can happen spontaneously.
What is activation energy?
The energy reactions require to destabilize chemical bonds and start exergonic reactions.
What is a catalyst, and what does it do?
An enzyme that lowers the activation energy for the reaction occur.
Speed up chemical reactions.
What are enzymes considered?
Biological catalysts.
What do enzyme names usually end with?
-ase
What certain areas do enzymes have?
active sites.
What is a substrate?
The reactants that bind to the enzyme at the active site.
What is the enzyme-substrate complex?
The act of a substrate binding to the active site.
What is the 4 step process of the enzyme-substrate complex?
1) Substrate (reactants) approach enzyme
2) Substrate binds to the enzyme, and the enzyme changes shape leading to induced fit between the enzyme and substrate.
3) Reactions are catalyzed
4) The products are released and the enzyme returns to starting form.
What are multi-enzyme complexes?
Enzymes that are associated together and catalyze similar reactions.
What are factors that affect enzyme activity?
1) Temperature
2) pH
3) Inhibition
What are ribozymes?
RNA catalysts.
How does temperature affect enzyme activity?
Enzyme activity usually increase with temperature until a maximum is reached, and activity stops.
How does pH affect enzyme activity?
Enzymes have a tolerance range usually of pH 6-8.
Enzymes in the stomach function at a pH of 2.
How does inhibition affect enzyme activity?
Any substance that binds to an enzyme and lower its activity.
What are two kinds of inhibition?
1) Competitive
2) Non-Competitive
When does competitive inhibition occur?
When the inhibitor wants to bind to the same active site as the substrate, preventing the substrate from binding to the active site causing it to be clogged.
When does non-competitive inhibition occur?
When the inhibitor binds to an allosteric site, changing the site of the active site, and preventing the target substrate from binding to the active site.
