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Biology I, Chapter 7

Terms in this set (17)

What is the difference between potential energy and kinetic energy? Where is much of the potential energy stored in a cell?
Potential energy is the capacity to do work while kinetic is the actual energy in motion, it is stored with the covalent binds in the chemical bonds
What are the tenets of the first and second laws of thermodynamics? How do they apply to biological systems?
1. Energy cannot be created or destroyed
2. Energy of any open system and its surroundings is constant
3. However, energy can be transferred/converted (including between matter and light)
4. Organisms cannot create the energy they require to live- they capture it from the environment and convert it to a form they can use for work
Does biological organization violate the second law of thermodynamics? Why or why not?
- No, it's problematic to equate "entropy" with "chaos"- it all must dop with the energy available for work in the system
- Also, organism are open systems, using energy from their surroundings to grow and develop
How are enthalpy, free energy, and entropy related to one another? (You should know the equation that expresses this, and you should understand how a change in one of these variables would affect the other variables.)
- Enthalpy (H) is the total potential energy in a system (essentially the energy in chemical bonds)
- Free energy or Gibbs free energy (G) is the amount of energy available to do work under given conditions
- Entropy (S) is the measure of disorder or randomness of energy; specifically, it quantifies how much energy is unavailable for doing work
G = H - TS
What are coupled reactions? Why is it necessary for cells to couple reactions?
Coupled reactions occur when an exergonic reaction provides the free energy necessary to drive an endergonic reaction
How does ATP help fuel the cell's metabolism? What is happening at the chemical level during this process (i.e., what parts of ATP are involved)?
Metabolism is the sum of all chemical activities taking place in an organism so ATP is needed for almost all functions of everything
Is a molecule storing more energy when it is oxidized or reduced?
- Oxidation occurs when a substance loses electron
- Reduction happens when a substance gains electrons
How does a catalyst differ from the reactants of a reaction? Thermodynamically-speaking, how does a catalyst speed up a reaction?
Catabolism is when larger molecules are broke down into smaller ones and is the opposite of anabolism which is complex molecules are synthesized from simpler substances
Why are enzymes so specific? Can an enzyme have more than one particular substrate?
Enzymes are biological catalysis used by the cells to increase the rates of various chemical equations
Where in the enzyme is the cofactor typically located?
Some enzymes require a cofactor- an additional chemical component needed to catalyze reactions
- Can be organic and be called coenzymes
- Can be inorganic and often be metal ions
They are often positioned in the enzymes active site
What is denaturation? (You should be able to explain what this is at the molecular level and understand why this happens.)
Process of modifying the molecular structure of a protein by breaking many of the weak linkages and binds which are part of its highly ordered structure of the protein in its natural state
How does temperature affect the rate of an enzymatic reaction? Can the temperature get too high? If so, what happens to the enzyme?
Increases in temp > increases in reaction rate, up until the enzyme becomes denatured
How does pH affect the rate of an enzymatic reaction?
Enzymes have an optimal pH and changes in pH can lead to denaturation
What are the different ways that a cell can regulate enzyme activity?
1. Regulate amount of enzyme produced
2. Regulate amount of substrate present
3. Enzyme inhibition
How does substrate concentration affect the rate of an enzymatic reaction? What happens when an enzyme becomes saturated?
At a high substrate concentration, enzymes are saturated and cause a reaction to be slower and less evident in the beginning
What is the difference between competitive and noncompetitive inhibition? How can we tell the difference experimentally? (Hint: think about substrate concentration.)
- Competitive inhibition occurs when a substance competes with the normal substrate for the enzymes active site
- Noncompetitive inhibition occurs when a substance binds to a site other than the active site (called an allosteric site)
The increases in substrate concentration can overcome the effects of a competitive inhibitor
How does feedback inhibition work? Why is this necessary?
This occurs when the product of the reaction at the end of a metabolic pathway inhibits an earlier reaction in the pathway, this is necessary to not allow over/under production of enzymes
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