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Proteins and Enzymes. Thermodynamics. The study of energy in living systems. Two laws of thermodynamics. 1 st law of thermodynamics : conservation of energy. Energy is neither lost nor gained but just changes from one form to another . 2 nd law of thermodynamics : entropy
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Thermodynamics The study of energy in living systems
Two laws of thermodynamics • 1st law of thermodynamics: conservation of energy. Energy is neither lost nor gained but just changes from one form to another. • 2nd law of thermodynamics: entropy • Tendency to move from order to disorder.
Conservation of energy • Energy can neither be created nor destroyed. • Energy can only be changed from one form to another.
Entropy: disorder • For living beings or just molecules to be organized, a lot of energy is required. • Very little energy is needed to create disorder.
A B + C • Breaking down a reactant (A) into products (B and C) • Requires little energy to start breaking down substances • Exergonic reaction – releases energy
A + B C • Making a product (C) from reactants (A and B) • Requires much energy to start this reaction – Why? • Endergonic reaction – absorbs energy
Activation energy • Activation energy: how much energy is required to start a reaction
http://www.youtube.com/watch?v=-vgkvUxxZFg&feature=related • http://www.britishpathe.com/record.php?id=50144
Energy-Releasing Reaction Energy-Absorbing Reaction Activation energy Products Activation energy Reactants Reactants Products Activation energy on two types of reactions
Graph of Energy of a reaction Which graph is Endergonic? Which graph isExergonic?
Enzyme action • Enzymes: special proteins that help to reduce the activation energy (Ea) • What will enzymes do to the speed (rate) of a reaction?
Effects of Enzymes Reaction pathway without enzyme Activation energy without enzyme Activation energy with enzyme Reactants Reaction pathway with enzyme Products
How do enzymes help with the activation energy required for metabolic processes?
DNA Amino acids Polypeptide= protein
Enzymes are Proteins (made of amino acids) • Remember, All enzymes are Proteins
Figure 2-21 Enzyme Action Enzyme activity (1) Section 2-4 Enzyme (hexokinase) Glucose Substrates ADP Products Glucose-6- phosphate ATP Products are released Active site Substrates bind to enzyme Enzyme-substrate complex Substrates are converted into products
Figure 2-21 Enzyme Action Enzyme activity (2) Section 2-4 Enzyme (hexokinase) Glucose Substrates ADP Products Glucose-6- phosphate ATP Products are released Active site Substrates bind to enzyme Enzyme-substrate complex Substrates are converted into products
Figure 2-21 Enzyme Action Enzyme activity (3) Section 2-4 Enzyme (hexokinase) Glucose Substrates ADP Products Glucose-6- phosphate ATP Products are released Active site Substrates bind to enzyme Enzyme-substrate complex Substrates are converted into products
Enzyme activity (4) Figure 2-21 Enzyme Action Section 2-4 Enzyme (hexokinase) Glucose Substrates ADP Products Glucose-6- phosphate ATP Products are released Active site Substrates bind to enzyme Enzyme-substrate complex Substrates are converted into products
Proteins can be Denatured • Denature – changes the Secondary, Tertiary or Quaternary structure of a protein. • Heat and pHchanges are the most common ways to denature a protein (polypeptide).
Enzymes and Metabolism • Enzymes facilitate the metabolic processes (chemical reactions) to sustain life. • Enzymes help to maintain homeostasis. • Enzymes help to build cells. • Enzymes help in reproduction.
