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Introduction to Metabolism

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Introduction to Metabolism Biology is applied Chemistry! Metabolism Metabolism is the totality of an organism s chemical reactions Metabolism is an emergent ... – PowerPoint PPT presentation

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Title: Introduction to Metabolism


1
Introduction to Metabolism
  • Biology is applied Chemistry!

2
Metabolism
  • Metabolism is the totality of an organisms
    chemical reactions
  • Metabolism is an emergent property of life that
    arises from interactions between molecules within
    the cell
  • Catabolic pathways release energy by breaking
    down complex molecules into simpler compounds
  • Anabolic pathways consume energy to build complex
    molecules from simpler ones

3
Energy (energy concepts video)
  • Energy The capacity to do work
  • Kinetic Energy The energy to do work
  • Heat (thermal energy) is kinetic energy
    associated with random movement of atoms or
    molecules
  • Potential energy Energy that matter possesses
    because of its location or structure
  • Chemical energy is potential energy available for
    release in a chemical reaction

4
  • Organisms are energy transformers
  • Sunlight ? ? Glucose ? ? ? Life functions
  • (kinetic) (potential-stored) (kinetic)
  • Bioenergetics is the study of how organisms
    manage their energy resources

5
Laws of Thermodynamic
  • 1st Conservation of Energy. Energy can not be
    created or destroyed. (but it can be transferred
    or transformed)
  • 2nd Every energy transfer or transformation
    increases the Entropy of the universe.
  • During every energy transfer or transformation,
    some energy is unusable, and is often lost as
    heat

6
Exergonic reactions release energy
7
Endergonic reactions require energy
8
Energy Coupling
  • Energy Coupling use of an exergonic process to
    drive an endergonic process.
  • ATP is the energy coupler / currency of energy
    coupling.

9
ATP --------? ADP Pi energy
10
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11
Metabolic Pathways
  • A metabolic pathway begins with a specific
    molecule and ends with a product.
  • Each step is catalyzed by a specific enzyme

12
Enzymes (enzyme video overview)
  • Biological catalysts
  • A catalyst is a chemical agent that speeds up a
    reaction without being consumed by the reaction
  • Usually proteins
  • Lower the activation energy of a reaction
  • Every chemical reaction between molecules
    involves bond breaking and bond forming
  • The initial energy needed to start a chemical
    reaction is called the activation energy (EA)

13
Enzymes
  • An enzymes activity can be affected by
  • Environmental factors, such as temperature and pH

14
Enzymes are substrate specific
  • Active site restricted region of the enzyme
    molecule which binds to the substrate
  • Some require Cofactors
  • Inorganic (metal ions Zn, Fe, Cu)
  • Organic also called coenzymes (most vitamins
    are coenzymes)

15
Mechanism of Action (generalized)
  • 1. Substrate binds at enzyme active site
  •  
  • 2. Enzyme changes shape in response to the
    substrate
  • (Enhanced fit or Induced fit)
  •  
  • 3. Shape change brings chemical groups of
    molecules into positions to
  • enhance the reaction. Bonds break/bonds form
  •  
  • 4. Product formed which no longer fits the
    active site and is therefore released
  •  
  • 5. Enzyme returns to original shape and is ready
    to go again!

16
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17
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18
Controls on enzyme activity
  • Substrate concentration
  • Inhibitors
  • Competitive inhibitors
  • Noncompetitive inhibitors

19
Inhibitors
20
Real WorldAntifreeze (ethylene glycol) poisoning
  • Dogs and cats are attracted to ethylene glycol by
    its sweet taste. Animals will voluntarily drink
    ethylene glycol if antifreeze is spilled or leaks
    onto garage floors or driveways.
  • Perhaps as many as 10,000 dogs and cats are
    victims of accidental poisoning by automobile
    antifreeze every year

21
Symptoms of ethylene glycol poisoning
  • Depression, vomiting, incoordination, excessive
    urination, excessive thirst, and muscle
    twitching. Within 30 minutes of ingestion.
  • In as little as 12 to 36 hours, severe kidney
    dysfunction characterized by swollen, painful
    kidneys and the production of minimal to no
    urine, may occur.
  • The dog or cat may be seizuring, be comatose.
    Or dead!
  • WHY?

22
The Problem
  • Ethylene glycol itself is not the problem per se.
  • The PROBLEM is the toxic products that are
    created by liver enzymes (alcohol dehydrogenase)
    acting upon the ethylene glycol.
  • These metabolites cause acidosis (the blood
    becomes dangerously acidic) and destruction of
    kidney function.

23
The SolutionLets get Rover hammered!!!!
  • Hooray for Competitive inhibition!
  • Ethanol can be used as a competitive inhibitor.
    It can outcompete ethylene glycol for the active
    site of the alcohol dehydrogenase enzyme.
  • If the enzyme molecules are busy with ethanol
    they wont be available to turn ethylene glycol
    into toxic metabolites.

Fomepizole, an inhibitor of alcohol dehydrogenase
is replacing the use of ethanol.
24
Allosteric regulation
  • Allosteric site specific receptor site on some
    part of the enzyme molecule other than the active
    site
  • Activators as well as inhibitors may exist

25
Feedback Inhibition
  • In feedback inhibition, the end product of a
    metabolic pathway shuts down the pathway
  • Feedback inhibition prevents a cell from wasting
    chemical resources by synthesizing more product
    than is needed
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