chapter 8 metabolism. slide 2 of 23 overview cell is a chm factory macromolecules are made and...
TRANSCRIPT
Chapter 8Metabolism
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Overview
Cell is a CHM factory Macromolecules are made and broken down Cellular Respiration powers the factory
Extracts Energy stored in sugars (& other fuels)
Cells use the Energy from cellular respiration to perform various types of work Active transport of solutes into the cell Bioluminescence
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Metabolism
Metabolism – Totality of an organism’s chm reactions
Consists of 2 types of pathways Catabolic Pathway
Breakdown of complex molecules into simpler compounds Release of energy Digestion
Anabolic Pathway Simpler molecules Complicated molecules Consumes energy Polymerization
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Metabolic Pathways
Begin with a specific molecule
Altered in a series of defined steps Each step is catalyzed by an enzyme
Mechanisms regulate enzymes Prevents molecular deficits & surpluses
Creates a specific product
Enzyme 1 Enzyme 2 Enzyme 3
A B C DReaction 1 Reaction 2 Reaction 3
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Enzymes
Enzymes are biological catalysts
Proteins
Catalyst Lower activation energy Increases the rate of the reaction Affects nothing other than the reaction rate Does NOT affect the free energy of the reaction
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Enzyme Activity is affected by…
Metabolism – Totality of an organism’s chm reactions
Concentration of substrate
Concentration of enzyme
If enzyme is saturated, then rate is determined by enzyme’s rate for substrate product
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Enzymatic Regulation
Enzymes = proteins Proteins have 3D
structure Affected by pH and
Temperature Structure & function
relationship
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Enzyme Assistants
Cofactors Nonprotein molecules that enzymes require
for catalytic activity Typically, inorganic
Such as zinc, iron, and copper
Coenzymes Organic cofactor (what does organic mean?) Vitamins
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Competitive Inhibition
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Pathway Regulation
2 main ways to regulate metabolic pathways: 1. Switching on/off genes 2. Regulating enzyme activity
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Allosteric Regulation
Allosteric – specific binding site NOT the active site!! Can be inhibition or activation
Allosteric molecule binds to a site other than the active site
Allosteric molecule binding enzyme shape change Change in enzyme shape active site shape change Structural change = Functional change
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Allosteric Regulation
Enzyme units oscillate between two conformational sites One is catalytically active, the other is
inactive
Regulatory site Called allosteric site Activator or inhibitor binds and stabilizes the
conformational form Usually an activator or inhibitor affects all
active sites
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Cooperativity
When a substrate molecule causes an induced fit in one active site triggers the same change in all subunits of the enzyme
Amplifies the response of enzymes to substrates Primes the enzyme to accept more substrate
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Feedback Inhibition
A metabolic pathway is switched off by the inhibitory binding of its end product to an enzyme that acts early in the pathway
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