What can we use to help with chemical reactions? Agenda for Monday Oct. 25 th 1.Chemistry 2.Enzymes

Matter Matter occupies space and has weight – solid, liquid, or gas It may be possible to break some kinds of matter down into other kinds of matter with different properties. – Example, water (H 2 O) can be broken down into hydrogen and oxygen. Hydrogen and oxygen in the above example cannot be broken down any further because they are elements.

Elements Elements cannot be broken down – Elements are substances made up of only one kind of atom – The smallest particles of an element that have the characteristics of that element are atoms Substances that are composed of two or more different elements are called compounds. – Example, water is a compound because it is composed of hydrogen and oxygen The following elements make up 96% of the body weight of organisms: Carbon, Hydrogen, Oxygen, Nitrogen, Phosphorous, Sulfur

Atoms An atom is composed of subatomic particles. – protons, neutrons, and electrons Protons and neutrons are located in a central area called the nucleus Electrons move about the nucleus – # of electrons = #of protons Protons – positively charged Neutrons – not charged Electrons – negatively charged

Bonds Covalent Bonds – share electrons Ionic Bonds – transfer electrons Hydrogen bonds - attraction between the hydrogen and a negatively charged atom

Van der Waals Forces Attractions between postive and negative regions that pull and hold molecules together Strength depends on size, shape, and ability to attract electrons

Water Covers approximately 71% of Earth's surface. Life evolved in water Living things are 70-90% water In nature, water is a solvent for many kinds of chemical reactions Forms hydrogen bonds with other polar or charged particles – Strong Van der Waals force

At any instant in time, a large proportion of water molecules are bonded to nearby water molecules, giving water a cohesive property. Water molecules are attracted to other polar substances causing them to adhere to many kinds of materials.

This water strider is able to remain on the surface of water because of hydrogen bonding between the molecules. The insect is light and it’s weight is spread over the water so that there is not much weight at any one point.

Chemical Reactions Process in which atoms or groups of atoms are reorganized into different substances Chemical equation – shows reactants and products Reactant – starting substances Product – substance formed

Energy of Reactions Reactions require energy Minimum amount of energy needed for reactants to form products is called activation energy

Enzymes Catalyst – lowers the activation energy needed to start a chemical reaction – Speeds up a chemical reaction Enzymes are biological catalysts – Reactants that bind to the enzyme are called substrates – Specific location where a substrate binds on an enzyme is called active site

What is a catalyst? Agenda for Tuesday Oct 26 th 1.Enzyme lab 2.Finish Enzyme Notes

Anabolic/Endothermic Reactions Anabolic reactions are those that synthesize compounds – Energy is required for these reactions – Uses heat – Creates larger molecules

Catabolic/Exothermic Reactions Reactions that break down molecules are called catabolic reactions – Energy is released when molecules are broken down – Heat is released

Enzymes Catalysts – Enzymes are specific for one particular reaction or group of related reactions. Many reactions cannot occur without the correct enzyme They are often named by adding "ase" to the name of the substrate – Example: Dehydrogenases are enzymes that remove hydrogen.

Induced Fit Theory Enzyme-substrate complex forms – enzyme’s active site binds with the substrate like a key fitting a lock – **Key and Lock Model **

Enzyme Shape The shape of the enzyme must match the shape of the substrate – Enzymes are very specific – Will only function correctly if the shape of the substrate matches the active site

What does lock and key refer to when talking about enzymes? Agenda for Wednesday Oct. 27 th 1.Review Enzymes 2.Catalase Lab Part 1

Catabolic and Anabolic Catabolic – breaks down molecules Anabolic – builds larger molecules Induced fit theory – enzymes are specific to the substrate

Catalase Lab Catalase – enzyme found in almost all living things – Breaks down hydrogen peroxide (dangerous byproduct) – 2 H 2 O 2 → 2 H 2 O + O 2 – High concentration in liver in humans – Stored in cell organelles called Peroxisomes

What is catalase? What role does it play in cells? Agenda for Thursday Oct 28 th 1.Finish Catalase Lab 2.Finish enzyme notes

What are the 6 main elements that make up most organisms? Agenda for Friday Oct 29 th 1.Quiz 2.Finish Enzyme Notes 3.Macromolecules

Conditions that affect enzymes Substrate Concentration Reaction rate increases as substrate concentration is increased then levels off

Conditions that affect enzymes Enzyme Concentration Reaction rate increases as enzyme concentration is increased then levels off

Conditions that affect enzymes Temperature Higher temperature causes more collisions among the molecules and increases the rate of a reaction Above a certain temperature, activity begins to decline because the enzyme begins to denature

Conditions that affect enzymes pH Each enzyme has an optimal pH A change in pH can alter the charges on the amino acids change – molecule changes shape – the new shape may not be effective

Regulation of Enzyme Activity Regulation of Protein Synthesis (Genetic Regulation) Enzymes are proteins You can regulate them by making more or less of them as needed

Regulation of Enzyme Activity Competitive Inhibition A similar-shaped molecule competes with the substrate for active sites

Regulation of Enzyme Activity Another form of inhibition involves an inhibitor that binds to an allosteric site of an enzyme – An allosteric site is a different location than the active site – alters the shape of the enzyme, resulting in an active site that does not function properly – Usually temporary

Regulation of Enzyme Activity Feeback Inhibition Thermostat Same in Enzymes – As an enzyme's product accumulates, it turns off the enzyme – the end product of the pathway binds to an allosteric site on the first enzyme and shuts down the entire sequence

Coenzymes Many enzymes require a cofactor to assist in the reaction. – Nonprotein/metal ions such as magnesium, potassium, and calcium – Cofactors bind to the enzyme and remove electrons, protons, or chemical groups Vitamins usually act as coenzymes or precursors to coenzymes

Macromolecules