Chemical Basis of Life

Matter– Anything that occupies space and has mass

Mass– The amount of matter in an object (kg)

Weight– Gravitational force acting on an object of a given

mass

Element– Simplest type of matter with unique chemical

properties

Atoms– Smallest particle of an element that has chemical

characteristics of that element– Composed of subatomic particles

Subatomic particles– Neutrons: no electrical charge– Protons: positive charge– Electrons: negative charge

Nucleus– Formed by protons and neutrons– Most of the volume of an atom

Atomic mass and Mass number

Atomic number– Equals the number of protons – Equals the number electrons (in a neutral atom)– The element number in the periodic table

Atomic mass (mass number)– Protons plus the neutrons– The lower number in the periodic table

Isotopes and Atomic mass

Isotopes– 2+ forms of the same element but with a different

neutron number– Denoted by using the symbol of element

preceded by mass number as (1H, 2H)

Electrons and chemical bonding

Ion– When an atom loses or gains electrons and

becomes charged Cation: positively charged ion (losses electrons) Anion: negatively charged ion (gains electrons)

Ionic bonding– Cations and anions are attracted to each other– A transfer of electrons

Covalent bonding

Atoms share pairs of electrons– Single covalent: One pair is shared– Double covalent: Two atoms share 4 electrons

Nonpolar covalent: equal sharing

Polar covalent: unequal sharing

Molecules and compounds

Molecules– 2+ atoms held by a covalent bond– Example: water

Compounds– A substance composed of 2+ elements in a fixed ratio– Example: hydrogen molecules

Molecular mass– Determined by adding up atomic masses of its atoms

or ionsExample: NaCl (22.99 + 35.45)

Intermolecular forces

Result from weak electrostatic attractions between oppositely charged parts or molecules

Weaker than forces producing chemical bonding

Examples of forces

Hydrogen bonds– Water: positively charged hydrogen atoms bond

with negatively charged oxygen atoms of other water molecules

– Important in determining shape of complex molecules

Intermolecular forces

Solubility: ability of one substance to dissolve the other– Solute is the material dissolved – Solvent is the media that does the dissolving

Intermolecular forces

Electrolytes– Cations and anions that dissociate in

water

Nonelectrolytes– Molecules that do not dissociate form

solutions that do not conduct electricity

Chemical Reactions

Chemical reactions: Atoms, ions, molecules, or compounds that interact to form or break chemical bonds

– Metabolism: all anabolic and catabolic reactions in the bodyCatabolism: Decomposition reactionsAnabolism: growth, maintenance, and repair

Oxidation-reduction reaction

Oxidation:– Loss of an electron by an atom

Reduction– Gain of an electron by an atom

Oxidation-reduction reactions– The complete or partial loss of an electron by one

atom is accompanied by the gain of that electron by another atom

– “LEO the lion says GER”

Speed of chemical reaction

Activation energy– Minimum energy reactants must have to start

a chemical reaction– Catalysts: substances that increase the rate of

chemical reactions without being permanently changed or depleted

– Enzymes: increase the rate of chemical reactions by lowering the activation energy

Water

Inorganic Stabilizes body temperature Protection Necessary for many chemical reactions Mixing medium

– Mixture: substance physically but not chemically combined

Acids and bases

Acid: A proton donor or any substance that releases hydrogen ions

Base: a proton acceptor or any other substance that binds to or accepts hydrogen

Buffers: a solution of a conjugate acid-base pair in which acid or base component occur in similar concentrations

The pH scale

Refers to the hydrogen ion concentration in a solution– Neutral: pH of 7 or equal hydrogen and hydroxide

ions– Acidic: 0-7, greater concentration of hydrogen

ions– Basic: 7-14, greater concentration of hydroxide

ions (less Hydrogen ions)

Organic molecules

Carbohydrates– Carbon, hydrogen, oxygen

Lipids– Carbon, hydrogen, oxygen

Proteins– Carbon, hydrogen, oxygen, nitrogen

Nucleic acids– Carbon, hydrogen, oxygen, phosphorus– DNA and RNA

Carbohydrates

Monosaccharide– Simple sugars: glucose, fructose, galactose

Disaccharides– Two simple sugars bound by a dehydration

synthesis

Polysaccharides– Long chains of many monosaccharide– Glycogen, starch, cellulose

Lipids

Relatively insoluble in water Fats: ingested and broken down by

hydrolysis Triglycerides: composed of glycerol and 3

fatty acids Phospholipids: found in plasma membranes Steroids: cholesterol, bile salts, estrogen,

testosterone

Proteins

Amino acids: building blocks of proteins Peptide bonds: covalent bonds forms

between amino acids during protein synthesis

Example: enzymes

Nucleic acids

DNA: Deoxyribonucleic acid– Genetic material of cells copied from one

generation to another– Composed of 2 strands of nucleotides

Sugar, phosphate, and a base Adenine, thymine, guanine, cytosine

RNA: ribonucleic acids– Single strand– Uracil replaces thymine

ATP

Adenosine Triphosphate Energy currency of the body Made in the mitochondria during cellular

respiration.