Chemistry in Biology Section 2: Chemical Reactions

Reactants are the starting substances, on the left side of the arrow. Section 2 Chemistry in Biology Chemical Reactions Chemical Equations Chemical formulas describe the substances in the reaction and arrows indicate the process of change. Reactants are the starting substances, on the left side of the arrow. Products are the substances formed during the reaction, on the right side of the arrow.

Glucose and oxygen react to form carbon dioxide and water. Section 2 Chemistry in Biology Chemical Reactions Glucose and oxygen react to form carbon dioxide and water.

Section 2 Chemistry in Biology Chemical Reactions Balanced Equations The law of conservation of mass states matter cannot be created or destroyed. The number of atoms of each element on the reactant side must equal the number of atoms of the same element on the product side.

Section 2 Chemistry in Biology Chemical Reactions Energy of Reactions The activation energy is the minimum amount of energy needed for reactants to form products in a chemical reaction.

This reaction is exothermic and released heat energy. Section 2 Chemistry in Biology Chemical Reactions This reaction is exothermic and released heat energy. The energy of the product is lower than the energy of the reactants.

This reaction is endothermic and absorbed heat energy. Section 2 Chemistry in Biology Chemical Reactions This reaction is endothermic and absorbed heat energy. The energy of the products is higher than the energy of the reactants.

It does not increase how much product is made and it does not get used Section 2 Chemistry in Biology Chemical Reactions Enzymes A catalyst is a substance that lowers the activation energy needed to start a chemical reaction. It does not increase how much product is made and it does not get used up in the reaction. Enzymes are biological catalysts.

The reactants that bind to the enzyme are called substrates. Section 2 Chemistry in Biology Chemical Reactions The reactants that bind to the enzyme are called substrates. The specific location where a substrate binds on an enzyme is called the active site.

Section 2 Chemistry in Biology Chemical Reactions The active site changes shape and forms the enzyme-substrate complex, which helps chemical bonds in the reactants to be broken and new bonds to form. Factors such as pH, temperature, and other substances affect enzyme activity.

Photosynthesis Chapter 8 Light energy 6 CO2 + 6 H2O C6H12O6 + 6 O2 Carbon dioxide Water Glucose Oxygen gas Photosynthesis

Activating Prior Knowledge List the eight characteristics of living things.  List the three subatomic particles, their charge, and location within an atom. List the four classes of organic compounds. Include the monomer(s) and an example of each class of compounds.  List four differences between plant and animal cells. Which organelle carries out photosynthesis?  Which organelle converts chemical energy stored in food into compounds that are more convenient for the cell to use?  What is the name of the energy currency molecule of the cell?  Why are most plants green?

Do you remember any of the eight characteristics of living things? Living things are based on a universal genetic code (DNA) Living things grow and develop Living things respond to their environment (stimulus) Living things reproduce Living things maintain a stable internal environment (homeostasis) Living things obtain and use material and energy (metabolism) Living things are made up of CELLS Taken as a group, living things evolve over time

Three Subatomic Particles Proton: (+) charged particle found inside the nucleus Neutron: neutral particle found inside the nucleus Electron: (-) charged particle found outside the nucleus in various energy levels

Organic Compounds Carbohydrates Lipids Proteins Nucleic Acids Monomer: Monosaccharide Made up of: Carbon, Hydrogen, Oxygen (H:O in 2:1 ratio) Sugars – glucose, fructose, sucrose Lipids Glycerol and Fatty Acids (H:O not in 2:1 ratio) Oils, Waxes, Butter Proteins Amino Acid Carbon, Hydrogen, Oxygen, Nitrogen Enzymes Nucleic Acids Nucleotide 1) 5 Carbon sugar, 2) phosphate group 3)nitrogenous base Carbon, Hydrogen, Oxygen, Nitrogen and Phosphorus DNA and RNA

Differences between plant and animal Cell wall Chloroplast Photosynthesis Lysosomes only in specialized cells No centrioles No cell wall No chloroplast No photosynthesis Lysosomes Centrioles (cell division)

More review… Organelle for photosynthesis chloroplast Organelle to convert chemical energy into energy the cell can use mitochondria Energy currency of the cell ATP Why are plants green? Chlorophyll

Chemical Reactions in Biology Chapter 6.2

What are chemical reactions? Chemical reactions occur when the atoms of a substance are rearranged to form a new substance. In other words, the composition of a substance must change. Not necessarily the appearance of a substance, but what a substance is made of. Water can change to ice or steam, but the composition does not change. (H2O) Clues that a chemical change has taken place are the production of heat or light, or a formation of a new gas, liquid, or solid.

Chemical Changes

What is a clue that a chemical reaction has occurred? “Colorless hydrochloric acid is added to a red solution of cobalt(II) nitrate, turning the solution blue.” a) The color changes. b) A solid forms. c) Bubbles are present. d) A flame is produced.

What is a clue that a chemical reaction has occurred? “A solid forms when a solution of sodium dichromate is added to a solution of lead nitrate.” a) A gas forms. b) A solid forms. c) Bubbles are present. d) A flame is produced.

What is a clue that a chemical reaction has occurred? a) The color changes. b) A solid forms. c) Bubbles are present. d) A flame is produced.

Chemical Equations Chemical equations show what substances are involved in the reaction. The starting substances that will be changed in the reaction are called reactants. The final substances that were formed by the reaction are called the products. CO2 + H2O ---> C6H12O6 + O2 Reactants Products

Balancing Chemical Equations This equation is unbalanced. In other words it has the proper molecular formulas but not the correct number of atoms. Can you balance the equation? CO2 + H2O ---> C6H12O6 + O2 1 Carbon 6 Carbons 2 Hydrogens 12 Hydrogens 3 Oxygens 8 Oxygens

THE LAW OF CONSERVATION OF MASS The principle that lies at the heart of the balancing process is that atoms are conserved in a chemical reaction. Atoms are neither created nor destroyed. The same number of each type of atom is found among the reactants and among the products.

Activation Energy Most chemical reactions require an energy source in order to start the reaction. The minimum amount of energy that is required to start a reaction is called the Activation Energy. A Catalyst is a substance that lowers the activation energy of a chemical reaction. Another important property of a catalyst is that it does not get used in the reaction. That means it is reusable.

Activation Energy with Endothermic and Exothermic Reactions Energy of Reactions The activation energy is the minimum amount of energy needed for reactants to form products in a chemical reaction.

This reaction is exothermic and released heat energy. The energy of the product is lower than the energy of the reactants.

This reaction is endothermic and absorbed heat energy. The energy of the products is higher than the energy of the reactants.

Enzymes Enzymes are special proteins essential to life that act as biological catalysts. They speed up normal body reactions without being used up in the reaction themselves. Without enzymes, our bodies would not function. Normal metabolism requires thousands of complex chemical reactions. Without enzymes, these reactions in our bodies could not take place.

Enzymes and Activation Energy

Examples of Enzymes and their Function Amylase – Breaks down starches Cellulase – Breaks down cellulose Lactase – Breaks down dairy products Lipase – Breaks down fats Maltase – Breaks down grains Protease – Breaks down proteins Sucrase – Breaks down sugars

How an Enzyme works Enzymes can only react with certain reactants. It kind of works like a puzzle. Specific reactants in a reaction are called substrates. Substrates have a specific site that only matches with a specific enzyme. The matching site is called the active site. Once the active site on the substrate matches with an enzyme, the enzyme causes the substrate to change shape or form to make new products. Then the enzyme is released.

Enzymes and Substrates Enzymes can be destroyed or affected by certain factors such as high or low pH and high or low temperatures. Optimum enzyme activity in humans and most endotherms is 37 C0 or 98.6 F0.

Which of the following particles is negatively charged? Chapter Chemistry in Biology Chapter Diagnostic Questions Which of the following particles is negatively charged? electron isotope neutron proton A B C D CDQ 1

Isotopes are created by a change in the Chapter Chemistry in Biology Chapter Diagnostic Questions Isotopes are created by a change in the number of what particle of an atom? electrons neutrons protons ions A B C D CDQ 2

Identify the proteins that speed up the rate of chemical reactions. Chapter Chemistry in Biology Chapter Diagnostic Questions Identify the proteins that speed up the rate of chemical reactions. substrates enzymes ions reactants A B C D CDQ 3

What particles are in an atom’s nucleus? Chapter Chemistry in Biology Section 1 Formative Questions What particles are in an atom’s nucleus? neutrons and electrons protons and electrons protons and neutrons A B C FQ 1

What causes the overall charge of an atom to be zero? Chapter Chemistry in Biology Section 1 Formative Questions What causes the overall charge of an atom to be zero? an equal number of protons and neutrons an equal number of protons and electrons an equal number of neutrons and electrons A B C FQ 2

What type of substance is water? Chapter Chemistry in Biology Section 1 Formative Questions What type of substance is water? a compound an element an isotope a mixture A B C D FQ 3

What provides the energy for all living processes? Chapter Chemistry in Biology Section 1 Formative Questions What provides the energy for all living processes? chemical bonds ionic compounds radioactive isotopes van der Waals forces A B C D FQ 4

Which is a chemical reaction? Chapter Chemistry in Biology Section 2 Formative Questions Which is a chemical reaction? a match burning salt dissolving water boiling gasoline evaporating A B C D FQ 5

A B Which chemical reaction is endothermic? Chapter Chemistry in Biology Section 2 Formative Questions Which chemical reaction is endothermic? A B FQ 6

How does an enzyme increase the rate of a chemical reaction? Chapter Chemistry in Biology Section 2 Formative Questions How does an enzyme increase the rate of a chemical reaction? It acts as a reactant. It reduces the amount of heat produced. It increases the amount of product. It lowers the activation energy. A B C D FQ 7

What occurs at the active site in the enzyme substrate complex? Chapter Chemistry in Biology Section 2 Formative Questions What occurs at the active site in the enzyme substrate complex? An exothermic chemical reaction takes place. Chemical bonds are broken and new bonds are formed. The enzyme gets used up in the reaction. The substrates provide energy for the enzyme. A B C D FQ 8