Exam 2: Topic 9 Flashcards
Understand the vital necessity for functioning enzymes in all life.
▪ Enzymes are crucial to living things because they act as biological catalysts, significantly speeding up chemical reactions that are essential for life processes, such as digestion, respiration, and cell growth.
without these enzymes, these reactions would occur too slowly to sustain life across all types of organisms.
What are enzymes? How do they work?
▪ Enzymes are large proteins that lower the activation energy of a chemical reaction by:
○ attracting reactants to the enzyme.
○ stressing existing covalent bonds so they break, and
○ correctly orienting the reactants so that new covalent bonds are likely to form.
Can enzymes provide the energy necessary to fuel an anabolic reaction?
▪ No. Enzymes themselves do not provide the energy needed to fuel anabolic reactions.
▪ Their primary function is to lower activation energy; they do not directly contribute energy to the reaction itself.
What are some properties of enzymes? In particular, define coenzymes, cofactors,
activation energy, and the concept that enzymes are highly specific catalysts.
▪ Activation energy is the minimum amount of energy required for a reaction to occur.
▪ cofactor: an additional piece inserted before the enzyme is functional. Can be inorganic or organic.
▪ coenzyme: an additional organic piece inserted before the enzyme is functional.
▪ Enzymes are highly specific catalysts and typically only catalyze one particular reaction, acting on a specific type of substrate due to its unique shape of its active site.
Differentiate between a competitive and noncompetitive inhibitor. How do
bacteria employ these molecules to regulate their own metabolism? How do we
employ these strategies to control microbial growth?
competitive: mimic the structure of substrate and block the active site from the substrate. Can be overcome by increasing substrate concentration.
○ noncompetitive: bind to the enzyme at a site other than the active site. This binding changes the conformation of the enzyme, making the active site unable to bind its substrate. Cannot be overcome by substrate concentration.
Explore the effects of temperature and pH on enzyme-mediated reactions.
Specifically, describe how temp and pH affect enzymes outside of optimal
conditions. In other words, be able to explain why the temperature graph is
“tilted” while the pH graph is not.
▪ Temperature graph:
○ The enzymatic activity increases with increasing temperature until the enzyme is denatured by heat and thus inactivated. At that point, the reaction rate falls steeply.
▪ pH graph:
○ The enzyme illustrated is most active at about pH 5.0
○ At too low or too high of a pH the enzyme is denatured.
Explain anabolic, catabolic, and redox reactions. Which reaction types generally
yield energy?
▪ Anabolic: a chemical reaction that joins smaller molecules into larger ones, using energy to create new molecules
▪ Catabolic: break down large, complex molecules into smaller, simpler ones, releasing energy in the process
▪ Redox reaction: a chemical reaction that involves the transfer of electrons between two species. The species that loses electrons is oxidized, and the species that gains electrons is reduced. The energy released from this transfer can be harnessed as usable energy by living organisms, particularly within cellular processes like cellular respiration where the electron transport chain utilizes redox reactions to generate ATP.
Describe the three sources of energy that microbes can capture (listed in class).
▪ Light
▪ Organic Molecules
▪ Reduced inorganic molecules
What is a hypertonic environment? Why might a hypertonic environment slow
bacterial growth?
▪ Hypertonic environment is an environment with a high concentration of solute and low concentration of water compared to a cell.
▪ Hypertonic environments can kill microbes or limit their ability to reproduce. This environment can cause cells to shrink, shrivel, and die. Therefore, slowing overall growth.
