chemical basis of life. matter – anything that occupies space and has mass mass – the amount of...
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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.