Primary Secondary Tertiary Quaternary

Protein Structure

Energy

Outline

I. Introduction

A. Metabolism

B. Energy defined

II. Laws of Thermodynamics

III. Energy Transfer in Living Systems

A. Chemical Reactions

B. ATP

Metabolism

All the chemical reactions that occur in the cell Capacity to get and use energy to build, store,

break down, and eliminate substances necessary for growth and reproduction– Catabolism: reactions that break down large

molecules into smaller ones e.g. digestion

energy released– Anabolism: reactions that build larger molecules

from small ones e.g. protein built from AA subunitsenergy required

Energy

Definition: the ability to do work, cause change

Energy obtained from some cellular reactions is used for fueling other reactions

Thermodynamics: The study of energy

Laws of Thermodynamics

1st Law: Energy in the universe is constant– Energy can be transferred or transformed but it

cannot be created or destroyed– Also known as the Energy Conservation law– True for a closed system

Heat and Entropy

Heat is energy and can do work (steam engine) Conversion of any form or energy into heat is

not fully reversible, not all heat is usable energy Heat “lost”=energy no longer capable of doing

work Heat is “low quality” energy Unusable heat associated with disorder

(entropy) Energy flows from high quality to low quality

Laws of Thermodynamics

1st Law: Energy in the universe is constant– Energy can be transferred or transformed but it cannot be

created or destroyed– Also known as the Energy Conservation law– True for a closed system

2nd Law: Disorder in the universe is increasing– Entropy: measure of disorder– In a closed system entropy increases

Maintaining Order

Systems tend toward disorder How do you explain order of a cell, or an

organism? Input of energy required to maintain order

Energy Transfer in Living Systems

Each chemical reaction in a cell has reactants and products

2 types of chemical reactions:– Exergonic: energy released meaning reactants

have more energy than products. Occur spontaneously

– Endergonic: energy required meaning reactants have less energy than products

– Sometimes these reactions are coupled

Energy Transfer in Living Systems

Metabolic Pathway: series of chemical reactions– Often have reactants which are complexed into one or more

intermediates before final productsA + B → C → D → E + F

Where A, B are reactants C, D are intermediates E,F products

Specific enzymes required at each step (each arrow)

Chemical equilibrium: recall this occurs when forward and backward reactions occur at the same rate. Concentrations of reactants and products are stable but not necessarily equal

Metabolic Pathway with inhibition (subtraction symbols)

ATP

Adenosine triphosphate Nucleotide based molecule- ribose, adenine,

and 3 phosphate groups Cellular energy, powers cellular work Bonds between phosphate groups can be

broken by hydrolysis ATP + H2O ↔ ADP + Pi (inorganic phosphate) +

energy

Phosphate groups all negative-repulse each other, like a coiled spring

ATP molecule

ATP hydrolysis