Chapter 4 Study Guide Flashcards
Give a definition of “enzymes” What does the term mean in Greek?
Greek for “in yeast”. Enzymes are biological catalysts that increase the rate of chemical reactions. They are specific, easily denatured, and competitive.
Enzymes are made up of___________?
Enzymes are made of proteins. The only exception are a few special cases in which RNA demonstrates enzymatic activity, these are called ribosomes.
Complete the following phrase: One Gene, one__________.
Polypeptide
What is “activation energy”? How do enzymes speed up the rate of a reaction?
Activation energy is the amount of energy required for a reaction to proceed. Enzymes lower the activation energy of a reaction, which increases the rate of the reaction.
What does the term “conformation” mean?
Conformation means the shape of a molecule, enzyme, structure, etc.
What are reactants? Products? Substrates?
Reactants: subtrates in enzymes.
Products: Are released after the enzyme dissociates, this also yields free energy.
Substrates: reactant molecules of the enzyme.
What is the “active site”?
Are particular pockets that are active in catalyzing a reaction located on the enzyme.
In the naming of enzymes, we have their name end in:________.
~ase.
The only exceptions are: pepsin, trypsin, and rennin.
Most enzymes have a double worded name. The first word tells you ________& the second word names the_____________.
First tells u the substrate and second tells you the action
What are “isoenzymes”?
Isoenzymes are different models of the same enzyme, found in different locations of the body. Very useful in the diagnosis of a disease.
How is the presence of some enzymes in the plasma of use to us?
In clinical test, abnormally high plasma concentrations of a particular enzymes (think SGPT) are characteristic of certain diseases. (See Clinical on 92)
What did I have to say about the title of this section?
This section should be title things that influence enzyme activity. These are: 1. Temp and ph, concentration of cofactors and coenzymes 2. concentration of enzyme and substrate molecules in the solution and 3. the stimulatory and inhibitory effect of some products of enzymes action on the activity of the enzymes that helps to form these products.
How do both pH and temperature influence enzyme activity?
An increase in any of these influencers with increase the rate of nonenzyme-catalyzed and enzyme-catalyzed reactions.
What does pH optimum mean?
Each enzyme characteristically exhibits peak activity in a very narrow pH range, which is known as the pH optimum. If the pH is changes so that it is no longer within the enzyme’s optimum range, the reaction rate will decrease.
Over what pH range is trypsin effective?
Trypsin is effective between the 5 to 10 range, the pH optimum is 9.5
Pepsin is effective between the 1 to 6 range, the pH optimum is 2.
See Table 4.3 on 94
What are cofactors and what do they do?
Cofactors are necessary for the enzymes to have the proper shape. They assist with the conformation of the enzyme. All cofactors are metallic ions with plus 2 charges. (Ca, Mg, Mn, Cu, Zn, and Se (selenium)).
What are coenzymes and what do you do?
Coenzymes are organic molecules derived from water-soluble vitamins, such as niacin and riboflavin (mainly B vitamins).
In what ways might an enzyme be activated?
Activation of an Enzyme
-Remove excess amino acids
-Phosphorylate
-Dephosphoryation
Deactivation of an Enzyme
-Remove amino acid
-Dephoshorylation
-Phosphorylate
- destroy
Control gene expression
End product modulationBe able to explain what metabolic pathways are.
A sequence of enzymatic reactions that begins with an initial substrate, progress through a number of intermediates, and end with a final product. There are two types, linear and branched.
See Fig 4.7, 4.8. (A is Initial Substrate, B-E is Intermediates, F is the Final Product. The First Arrow at A is Enz 1, B to C is Enz 2, C to D is Enz3, D to E is Enz4, E to F is Enz5.)
A → B → C → D → E → F
Why would one branch of a pathway be more active than another?
Pathways keep Moving Forward because of
- Law of Mass Action - 2nd Law of Thermodynamics - Enzyme Specificity
Be able to explain “End Product Inhibition”
See fig 4.9 and 4.10.
End Product Inhibition is the regulation system of the branch points of metabolic pathways. This inhibition prevents that final product from accumulating excessively and results in a shift toward the final product of the alternate pathway.
How does this process work? That is, what is the mechanism of end Product Inhibition?
The mechanism by which the final product inhibits an earlier enzymatic step in its pathway is known as allosteric inhibition.
