Chemical Basis of Life

Matter and Energy Matter- anything that occupies

space and has mass solid, liquid, gas

Mass-amount of matter a substance contains

Energy potential, kinetic light, heat, electrical, chemical

Basic Molecular Structure

Matter is comprised of elements, 92 of which occur naturally

Elements cannot be broken down into simpler substances

Identified by chemical symbolsOxygen, carbon, hydrogen, and

nitrogen make up 96% of body’s massCompounds are combination of two or

more elements

Compound & MixturesCompound

Combined chemically

Alters properties of individual components

Combined in exact proportions

Mixtures Combined physically

Retains properties of individual components

Proportions may vary

Types of mixturesSolutions - homogeneous mixture

Solute = dissolved substance Solvent = dissolving medium Concentrations

percentmolarity

Colloids (emulsions) - undergo sol-gel transformations

Suspensions - visible solutes that settle

What is an atom?

-smallest part of an element showing characteristics of that element

ATOMIC STRUCTUREa tomos = “not cut”Subunits

protons-located in the nucleus (+)

neutrons-located in the nucleus (0)

electrons-located in energy shells (-)

ATOMIC CHARACTERISTICSAtomic number - number of protons in

the nucleusMass number - number of protons

plus the number of neutronsAtomic weight (mass) - sum of the

number of protons,neutrons, and electrons

Number of protons equal the number of electrons

A complete atom is electrically neutral.

There is NO NET CHARGE!

Atomic Structure

Isotopes atoms with the same numbers of protons but have different numbers of neutrons

isotopes of an element react in the same manner chemically

Radioisotopes

Heavier isotopes are usually radioactive

Examples Carbon 14 Iodine -131 Radium - 226 Cobalt - 60

Electron shellselectrons orbit the nucleus of an

atom in shells/energy levels1st level - holds 2 e’s2nd level - up to 8 e’s3rd level - up to 18 number and arrangement of

electrons determine if an atom is chemically stable

CHEMICAL BONDS

A. Chemical bonds and electrons1. chemical bonds are a union between atoms caused by the sharing or exchange of electrons.2. the type of bond is determined by the arrangement of the electrons in orbit around the nucleus.

3. electrons are attracted to protons, but repelled by other electrons

4. electrons are arranged in orbits (orbitals) around the nucleus.

5. the electrons in the outermost orbital are called the valence electrons

6. valence electrons determine the chemical reactivity of an atom.

7. octet rule - atoms form bonds to have 8 electrons in their valence shell

CHEMICAL REACTIONS

Molecule - two or more atoms joined together ex. H-H; O=O

Compound - combination of atoms of two or more elements ex. CO2, H2O

Chemical EquationsReactants – left side of the equationProducts – right side of the equationMolecular Formula ExampleC6H12O6 + 6O2 ----- 6CO2 + 6H2O +

Energy

Patterns of Chemical Reactions

Synthesis = combinationDecomposition = breakdownDisplacement = reactants

exchangeOxidation Reduction

reactants lose or gain electronsoxidized - loses electronsreduced - gains electrons

Factors affecting reactions

TemperatureParticle SizeConcentrationCatalysts

CHEMICAL BONDSCovalent - involve the sharing of electrons between atoms

Ionic - bonding involving the loss or gain of electrons thus forming ions cation (+) anion (-)

Polar covalent - due to the unequal sharing of electrons between atoms

Hydrogen - type of covalent bond due to sharing of hydrogen electrons with neighboring hydrogen atoms

INORGANIC MOLECULES

ElectrolytesAcidsBasesSaltspHWater

ELECTROLYTES

Substances that ionize and dissociate in water and are capable of conducting an electrical current

Form charged particles (ions) in solution

Include acids, bases, and salts

ACIDS and BASES

Acid = substance that releases hydrogen ions (H+) in solution

Acts as a proton donorHCl ----> H+ + Cl-

Base = substance that dissociate in solution into hydroxide (OH-)

Acts as a proton acceptorNaOH ---> Na+ + OH-

pH - measure of acidity or alkalinity

pH 7.0 - neutralacidic - pH < 7.0basic - pH > 7.opH = - log [H+]

pH - range 0 - 14body fluids = 7.35-7.45 (7.40)

SALTSAcids and bases react with

other to form salts when mixed in equal concentrations

HCl + NaOH H2O + NaCl(salt)

WATER

Excellent solvent Polarity

Serves as a reactantImportant lubricantHigh heat of vaporizationHigh heat capacity

ORGANIC MOLECULES

Contain carbon atoms linked to each other in chains or rings

-carbohydrates, proteins, lipids, nucleic acids

CARBOHYDRATES

INCLUDE SUGARS AND STARCHES

PROVIDE MOST OF CELL’S ENERGY

CARBON - HYDROGEN - OXYGEN 1 : 2 : 1 RATIO

Monosaccharide simple sugars contain 3-7 carbon atoms ex. glucose, fructose, galactose

Disaccharides are formed when 2 monomers are hooked together by dehydration synthesis reactions

ex. sucrose (table sugar);lactose (milk sugar)

Carbohydrates/Polysaccharides

Complex sugarsVery large macromolecules

formed when long chains of simple sugars are hooked together

Glycogen - storage form of glucose in animals

Starch - storage form of glucose in plants

PROTEINSAmino acids are the building blocks of

proteinsContain carbon, hydrogen, oxygen,

nitrogen20 amino acids occur naturallyEssential for cell structures and

function enzymes, receptors, blood proteins, structural support

PROTEIN STRUCTURE

LEVELS

Primary structureSecondary structureTertiary structureQuaternary structure

H l

NH2 - C - COOH

l R

LIPIDS

Contain carbon, hydrogen, oxygen but not in a 1:2:1 ratio

Non-polar molecules that will not dissolve in water

Functions as energy source, structural support, integral part of membrane

TYPES OF LIPIDSTRIGLYCERIDES

fats/oils saturated fatty acids unsaturated fatty acids

Phospholipids important membrane component amphipathic

Steroids sex hormones cholesterol

Eicosanoids prostaglandins involved in blood clotting, inflammation, and contractions

NUCLEIC ACIDSDNA - deoxyribonucleic acidRNA - ribonucleic acidConsist of nucleotides

5 carbon sugar nitrogenous base - (adenine, thymine, cytosine, guanine, or uracil (only in RNA)).

phosphate group

ATPAdenosine TriphosphateMain energy carrier for

individual reaction needs