Title: Introduction to Metabolism
1Introduction to Metabolism
- Biology is applied Chemistry!
2Metabolism
- 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
3Energy (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
5Laws 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
6Exergonic reactions release energy
7Endergonic reactions require energy
8Energy Coupling
- Energy Coupling use of an exergonic process to
drive an endergonic process. - ATP is the energy coupler / currency of energy
coupling.
9ATP --------? ADP Pi energy
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11Metabolic Pathways
- A metabolic pathway begins with a specific
molecule and ends with a product. - Each step is catalyzed by a specific enzyme
12Enzymes (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)
13Enzymes
- An enzymes activity can be affected by
- Environmental factors, such as temperature and pH
14Enzymes 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)
15Mechanism 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!
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18Controls on enzyme activity
- Substrate concentration
- Inhibitors
- Competitive inhibitors
- Noncompetitive inhibitors
19Inhibitors
20Real 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
21Symptoms 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?
22The 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.
23The 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.
24Allosteric 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
25Feedback 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