Chapter 8 Metabolism. Slide 2 of 23 Overview Cell is a CHM factory Macromolecules are made and...

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

Chapter 8 Metabolism. Slide 2 of 23 Overview Cell is a CHM factory Macromolecules are made and...

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