CHAPTER 6: THE CHEMISTRY OF LIFE

▸WHAT YOU WILL LEARN:

▸1. You will relate the structure of an atom to how it interacts with other atoms.

▸2. You will explain how water is important to life.

▸3. You will compare the role of carbon compounds in organisms.

▪WHY IT’S IMPORTANT:

▸Living organisms are made of simple elements as well as complex carbon compounds. With an understanding of these elements and compounds, you will be able to relate them to how living organisms function.

6.1 Atoms and their Interactions

Both living and nonliving things are composed of the same basic building blocks called Atoms

▪I. Elements▪Substance that can’t be broken down into

simpler chemical substances.▪90 naturally occurring elements

▪A. Natural elements in living things▪ Only about 25 of the Natural occurring

elements are essential to living organisms.

▪Four out of the 90 make up 96% of a human

▸(1) Carbon

▸(2) Hydrogen

▸(3) Oxygen

▸(4) Nitrogen

▪B. Trace Elements

▸Elements found in living things in very small amounts

▸Plants obtain trace elements by absorption

▸Animals get their trace elements by eating.

Chemical Reactions

Chemical reactions occur when bonds are formed or broken

All the chemical reactions in an organism are referred to as Metabolism – breaking down and building up

▪A. Writing chemical equations▸ Reactants – undergo chemical reactions H + O▸ Products – substances formed by chemical reactions

H2O,Table sugar C12H22O11, glucose C6H12O6

Mixtures and Solutions A mixture is a combination of substances in which the individual components retain their own properties

Sand/Sugar A solution is a mixture in which one or more substances (solute) are distributed evenly in another (solvent) Kool–Aid

▪A. Acids and Bases▸Chemical reactions can occur only when conditions

are right.▸Temperature▸Energy ▸ pH

▪The pH is measure of how acid or basic a solution is.Scale 0 7 14Acid Neutral Base H+ 0H-

6.2 Water and Diffusion

▪I. Water and its Importance▸Most life processes can occur only when molecules and

ions are free to move and collide with one another▸Water allows movement.

▸A. Water is polar A polar molecule is a molecule with

unequal distribution of charge. O- H+ H+

▸ Water attracts to water

▪ Hydrogen bonds - attractions between

hydrogen and oxygen▪ Capillary action

▪B. Water resists temperature changesWater is like an insulator, helps maintain a steady environment

▪C. Water expands when it freezes Ice on ponds Ice breaking rocks

II. Diffusion Particles of matter are in constant motion, colliding

with each other.

▪A. Early observation: Brownian motion Brown – pollen grain in water Dye particles

▪B. The process of Diffusion▸The net movement of particles from area of high

concentration to areas of low concentration.

▪Slow process because it relies on random

molecular motion.▪ Key factors: Concentration

Temperature Pressure

▪C. Diffusion in living systems

▸The differsnce in concentrations of a substance across space is called Concentration Gradients.▸Diffusion is one way cells move things in and out of

the cell (air/blood)

6.3 Life Substances “you are what you eat”

▪I. Role of Carbon in Organisms▸Single bond shares 1 pair of

electrons

▸Double bond shares 2 pairs of electrons

▸Triple bond shares 3 pairs of electrons

Carbon--because of its 4 outer electrons can form:

Straight chains

Branched chains

Rings

Compounds that have the same simple formula (what and how much) but different structures are Isomers

▪A. Molecular Chains▸Carbon compounds vary in size from two carbons to

thousands

▸A polymer is a large molecule formed when many smaller molecules bond together.

▪Condensation - water is removed from two smaller molecules that have H+ and an OH-

▪Hydrolysis - Polymers are broken apart by the insertion of a water molecule

▪B. The Structure of Carbohydrates

▸Contain C H O 2H to 1O▸Monosaccharides – simple sugar ▸( glucose and fructose)▸Disaccharide – two monosaccharide linked together.

( sucrose)

▸Polysaccharide – polymers composed of many monosaccharides. ( starch, glycogen, and cellulose )

▪C. The structure of Lipids

▸Contain C H O called fats and oils

▸Used for energy storage, insulation and protective coatings.

▪D. The structure of Proteins

▸Contain C H O N

▸Basic building blocks of protein are amino acids.

▸20 common amino acids

▸Peptide bonds hold amino acids together to form proteins

▸Proteins are the building blocks of our bodies

▸Proteins called Enzymes control the rate of many chemical reactions within the body

▪E. The structure of Nucleic acids▸Consist of Carbon, Hydrogen, Oxygen, and Nitrogen

Made of smaller units called NUCLEOTIDES

▸A Nucleotide has three groups of molecules:

▸ Five carbon sugar

▸ A phosphate group

▸ A base