Biology 107 Introduction to Metabolism II - PowerPoint PPT Presentation

1 / 17
About This Presentation
Title:

Biology 107 Introduction to Metabolism II

Description:

Introduction to Metabolism II. Properties ... Introduction to Metabolism II ... may be of two types: 1) competitive inhibitors or 2) noncompetitive inhibitors. ... – PowerPoint PPT presentation

Number of Views:42
Avg rating:3.0/5.0
Slides: 18
Provided by: Michael1764
Category:

less

Transcript and Presenter's Notes

Title: Biology 107 Introduction to Metabolism II


1
Biology 107Introduction to Metabolism II
  • September 15, 2003

2
Introduction to Metabolism II
  • Student Objectives As a result of this lecture
    and the assigned reading, you should understand
    the following
  • Enzymes act as catalysts (i.e., they participate
    in the reaction but are not reactants enzymes
    are not consumed or transformed chemically in
    reactions they catalyze).
  • Enzymes are proteins that increase the speed of
    the reaction by lowering the activation energy
    necessary for the reaction.

3
Introduction to Metabolism II
  • Properties of enzymes
  • a. Enzymes combine briefly with reactants during
    enzyme- catalyzed reactions.
  • b. Enzymes are relatively unchanged after
    catalyzing the conversion of reactants to
    products.
  • c. Enzymes are specific in their activity each
    enzyme catalyzes the reaction of a single type
    of molecule or a group of closely related
    molecules.
  • d. Enzymes are saturated by high substrate
    concentrations.
  • e. Many enzymes require non-protein groups,
    cofactors. Inorganic cofactors are metallic
    ions. Organic cofactors, coenzymes, are complex
    groups derived from vitamins.

4
Introduction to Metabolism II
  • Conditions affecting enzyme activity include 1)
    substrate concentration 2) temperature 3) pH
    4) cofactor concentrations.
  • Enzyme inhibitors can interfere with the activity
    of enzymes the inhibitors may be of two types
    1) competitive inhibitors or 2) noncompetitive
    inhibitors.
  • Oxidation-reduction reactions (redox reactions)
    - Oxidation the loss of electrons by a
    molecule, while reduction gain of electrons.
    In living systems, the energy-capturing reactions
    (photosynthesis) and energy-releasing reactions
    (glycolysis and respiration) are
    oxidation-reduction reactions.

5
Introduction to Metabolism II
  1. In an endergonic biosynthetic reaction, the
    electrons forming the chemical bonds of the
    product are at a higher energy level than the
    electrons of the reactants (i.e., the reaction
    requires input of energy).
  2. Cells supply the energy for endergonic reactions
    through coupled reactions in which endergonic
    reactions are linked to exergonic reactions.

6
Enzymes Lower Activation Energy But They Do Not
Change the Overall Energy Profile
7
The Enzyme Active Site Binds the Substrate(s)
8
The Reaction Environment Will Influence Reaction
Rates
Factors that may influence enzymatic reaction
rates include Temperature pH Substrate
concentration Cofactor concentration Enzyme
concentration
9
The Enzyme Active Site Binds the Substrate(s)
10
Example of Enzyme-catalyzed Reaction
11
Competitive Inhibitors Bind to the Active Site of
an Enzyme
12
Non-competitive (Allosteric) Inhibitors Bind to
Enzyme Sites Other Than the Active Site
13
Comparison of Competitive and Non-competitive
Inhibition of Enzymes
Inhibitors are specific for single enzymes or
closely related (structurally) enzymes. An
enzyme may have sites for both competitive and
non-competitive inhibitors
14
Allosteric Binding by Some Molecules Activates or
Stabilize Enzymes while Other Molecules May
Inhibit Enzymes
15
Inhibitors for a Pathway May Be End-products That
Feedback to Turn Off the Pathway
16
(No Transcript)
17
(No Transcript)
Write a Comment
User Comments (0)
About PowerShow.com