1. CHAPTER 2 – CHEMISTRY IN BIOLOGY CONT’D

2. Chemical Reactions
Definition: Process by which atoms or groups of atoms in a substance are reorganized into different substances
During this process chemical bonds are broken and formed
Example: Iron + Oxygen  Rust
Fe + O2  Fe2O3

3. Chemical Reactions
Not all changes in a substance is because of a chemical reaction some changes result from physical reactions
Example: Water

4. Chemical Equations A chemical equation shows the: Example: Table Salt
Starting Products ( Reactants)
Ending Products (Products)
Direction of the Reaction (Arrow)
Example: Table Salt

5. Balanced Equations
Law of Conservation of Mass: In chemical reactions matter cannot be created or destroyed.
All equations must show this balance of mass
# of atoms of each element on the reactant side = # of atoms of each element on the product side
Coefficients are used to make the number of atoms on each side of the arrow equal:

6. Balanced Equations
Example: Glucose

7. Energy of Reactions
Much of the energy organisms need is provided by sugar (food)
Chemical reactions breakdown food to provide energy
But we also need energy to start a chemical reactions.

8. Activation Energy
Activation Energy: The minimum amount of energy needed for reactants to form products in a chemical reaction.
Example: Flame provides the activation energy for the reaction of the wax with oxygen. After that no further input of energy is needed

9. Activation Energy
Activation Energy: Amount of energy needed to start a reaction.
Example: Flame provides the activation energy for the reaction of the wax with oxygen. After that no further input of energy is needed

10. Activation Energy
Energy Diagram: Is a representation of the energetic path that reaction must take from reactants to products.
Some reactions have very high activation energy

11. Exothermic Reaction: The net release of free energy
Eg. Breakdown of Sugar in the body

12. Endothermic Reaction: Reactions that involve a net absorption of free energy.
E.g. Photosynthesis

13. Increase how much product is made Get used up in a chemical reaction
Catalysts
Catalysts: A Substance that lowers the activation energy needed to start a chemical reaction. (i.e it speeds up a chemical reaction)
A Catalyst does not:
Increase how much product is made
Get used up in a chemical reaction

14. Enzyme: Is a special protein that acts as a biological catalyst
Catalysts - Enzymes
Enzyme: Is a special protein that acts as a biological catalyst
They speed up the rate pf chemical reactions in biological processes
Most enzymes are specific to one reaction
Amylase  Carbohydrates
Lipase  Fats

15. Enzyme Function
Substrates: Reactants or Substance that bind to the enzyme. This is what the enzyme is breaking down
Active Site: Specific location where a substrate binds to an enzyme
The active sight and the enzyme have complimentary shapes that enable them to act in a precise manner
Think about pieces of a puzzle
Lock & Key

16. Enzyme Structure Enzyme Substrate Complex:
Forms when the substrate binds to the active site
It helps chemical bonds in the reactants to be broken and new bonds to be formed.
One the reaction is complete the enzyme releases the product
The Enzymes are still reusable and go on to catalyze other reactions

17. Enzyme Structure Examples of Enzymatic Reaction
Snake Bite the enzymes in the snakes venom breaks down the membrane of the Red Blood Cell (RBC)
When fruits ripen
When we breakdown food in cellular respiration

18. Factors that affect Enzymes
Temperature
Human cells operate at ~37oC
Bacteria: Very high or Very low temperatures
Acidity
Inhibitors: A substance that blocks the enzyme from working properly
Enzyme Concentration
Substrate Concentration

19. Water & Solutions

20. Mixture
A mixture is a combination of two or more substances in which each substance retains its individual characteristics
Examples:
Water & Oil
Fruit and nut mix
Fruit basket

21. Mixture Two types of mixtures: Homogenous Mixture
Heterogeneous mixture
Also called a solution
Substances are uniformly distributed in another substance
Example:
Stainless Steel (Iron, chromium and nickel)
Salt water solution

22. Mixture Homogenous Mixture A homogenous mixture has two components:
Solvent: Substance in which another solution is dissolved
Solute: Substance which is dissolved in the solvent
Example: Salt & Water solution
Water is the solvent
Salt is the solute

23. Mixture Heterogeneous Mixtures
Components remain distinct that is you can tell that there are different things that make up the solution
A suspension is  a type of heterogeneous mixture where solid particles do not dissolve in a liquid solution. These particles settle out of the solution
Example:
Salad dressing
Sand and water

24. Mixture Heterogeneous Mixture
A colloid is  a type of heterogeneous where the particles do not settle out of the mixture because the particles are suspended in the mixture
Example:
Fog
Butter
Mayonnaise
Blood
Paint

25. Acids & Bases
Acid: Any substance that release Hydrogen ions (H+) in water
Base: Any substance that releases hydroxide ions (OH-) in water
pH: Is a measure of how much H+ ions or OH- is in a solution
The more H+ in a solution the more more acidic the solution will be
The more OH- in a solution the more basic the solution will be

26. Acids & Bases Acids: pH values between 0 and 7
Bases: pH values between 7 and 14
Neutral: pH of 7
Most processes carried out by our cells occurs between a pH of 6.5 to 7.5

27. Buffers Example: Antacids  Heartburn
Buffers: Are mixtures than can react with either an acid or a base to keep the pH within a certain range
Example: Antacids  Heartburn