Chapter 02 | Chemistry of Life

Atom

Atom

Smallest unit of matter that retains properties of an element.

Nucleus

Central core of an atom containing protons and neutrons.

Proton

Positively charged particle that determines atomic number.

Neutron

Neutral particle that contributes to atomic mass.

Atomic Number

Number of protons in the nucleus, unique to each element.

Atomic Mass

Combined number of protons and neutrons in an atom.

Electron

Negatively charged particle surrounding the nucleus.

Orbital

Regions around the nucleus where electrons are likely found.

Valence Electrons

Electrons in the outermost energy level determining chemical reactivity.

Electron Shells

Energy levels arranged in shells; first shell can hold 2 electrons, others hold more.

Octet Rule

Atoms are most stable with eight electrons in their valence shell.

Isotope

Variant of an element with different numbers of neutrons.

Element

Pure substance consisting of only one type of atom.

Periodic Table

Organizes elements based on atomic number and similar properties.

Essential Elements for Life

Includes carbon, hydrogen, nitrogen, oxygen, phosphorus, and sulfur (CHNOPS).

Molecule

Group of atoms chemically bonded together.

Diatomic Molecule

Molecule consisting of two atoms of the same element.

Compound

Substance made of molecules with different elements bonded together.

Chemical Formula

Represents the types and numbers of atoms in a compound.

Structural Formula

Shows the arrangement of atoms within a molecule.

Chemical Bond

Form when atoms interact to achieve a stable outer energy level.

Bond Energy

Amount of energy required to break a bond.

Ions

Atoms that have gained or lost electrons.

Cation

Positively charged ion formed by loss of electrons.

Anion

Negatively charged ion formed by gain of electrons.

Electrolytes

Ionic compounds that dissociate in water, conducting electricity.

Properties of Ionic Compounds

Have high melting points, form crystalline structures, conduct electricity in solution.

Covalent Bond

Atoms share electrons to complete their outer energy levels.

Nonpolar Covalent Bond

Electrons shared equally between atoms.

Polar Covalent Bond

Unequal sharing of electrons resulting in partial charges.

Single Bond

Covalent bond involving one pair of shared electrons.

Double Bond

Covalent bond involving two pairs of shared electrons.

Triple Bond

Covalent bond involving three pairs of shared electrons.

Hydrogen Bond

Weak bond formed between a slightly positive hydrogen atom and a slightly negative atom.

Cohesion

Water molecules sticking to each other.

Adhesion

Water molecules sticking to other surfaces.

Organic Compounds

Contain carbon-carbon or carbon-hydrogen bonds.

Functional Groups

Specific groups of atoms determining the properties of organic compounds.

Macromolecules

Large organic molecules essential for life processes.

Inorganic Compounds

Do not contain C-C or C-H bonds.

Water (H2O)

Inorganic, essential to life, acts as a solvent and participates in chemical reactions.

Acid

Increases H+ concentration in a solution.

Base

Decreases H+ concentration in a solution.

Salt

Formed by the neutralization reaction between acids and bases.

Buffer System

Chemical systems that resist changes in pH.

pH Scale

Measures H+ concentration, ranging from 0 to 14.

Monosaccharide

Simple sugars that are the basic units of carbohydrates.

Disaccharide

Two monosaccharides linked together.

Polysaccharide

Many monosaccharides linked together to form complex carbohydrates.

Glycogen

Storage form of glucose in animals.

Starch

Storage form of glucose in plants.

Cellulose

Structural component of plant cell walls, not digestible by humans.

Triglyceride

Lipids formed by glycerol and three fatty acids.

Phospholipid

Form the bilayer of cell membranes with hydrophilic heads and hydrophobic tails.

Cholesterol

Precursor for steroid hormones and stabilizes cell membranes.

Amino Acid

Building blocks of proteins linked by peptide bonds.

Enzyme

Biological catalyst that speeds up chemical reactions.

Active Site

Region on an enzyme where substrates bind and reactions occur.

Denaturation (of proteins)

Loss of protein structure and function due to extreme conditions.

Antibody

Specialized proteins produced by the immune system to neutralize foreign substances.

Nucleotide

Building blocks of nucleic acids composed of a phosphate group, a sugar, and a nitrogen base.

DNA (Deoxyribonucleic Acid)

Contains genetic information and guides protein synthesis.

Base Pairing

A pairs with T, C pairs with G in DNA structure.

RNA (Ribonucleic Acid)

Temporary copy of DNA for protein synthesis.

ATP (Adenosine Triphosphate)

Energy currency of the cell, providing energy for cellular activities.

Mitochondria

Powerhouses of the cell where ATP is produced through aerobic respiration.

Hydrophilic

Water-attracting, as seen in the heads of phospholipids.

Hydrophobic

Water-repelling, as seen in the tails of phospholipids.

Saturated Fatty Acid

Fatty acid with no double bonds between carbons; typically solid at room temperature.

Unsaturated Fatty Acid

Fatty acid with one or more double bonds; typically liquid at room temperature.

Trans Fats

Unsaturated fats that have been hydrogenated and can pose health risks.

Metabolism

The sum of all chemical reactions occurring in the body.

Hydrolysis

Breaking bonds by adding water.

Dehydration Synthesis

Forming bonds by removing water.

Chemical Stability

Achieved when atoms have full outer energy levels.

Electrolytes (in the body)

Essential for transmitting nerve impulses and muscle contractions.

Specificity (of enzymes)

Enzymes are specific to substrates due to their active site shape.

Cofactors

Non-protein molecules that assist enzymes in catalyzing reactions.

Coenzymes

Vitamins that function as cofactors for enzymatic reactions.

Temperature Regulation

Maintained through hydrogen bonding and water's high specific heat.

Hydrogen Bonds (in proteins)

Stabilize the structures of proteins, including alpha-helices and beta-pleated sheets.

Hydrogen Bonds (in DNA)

Help maintain the double helix structure.

Enzyme Function

Proper pH is vital for optimal enzyme activity.

Acidosis/Alkalosis

Conditions resulting from imbalances in blood pH.

Chemical Stability

Achieved by forming chemical bonds.

Structural Support

Provided by carbohydrates like cellulose in plants.

Energy Storage

Primary function of carbohydrates and lipids.

Cell Membrane Structure

Formed by phospholipids that create a barrier between the cell and its environment.

Hydrogen Bonding in Water

Key to water's unique properties, such as its high heat capacity.

Diatomic Elements

Elemental molecules composed of two identical atoms, like O2.

Acidic Solution

A solution with a pH less than 7.

Basic Solution

A solution with a pH greater than 7.

Neutral Solution

A solution with a pH of 7.

Cellular Respiration

Process by which cells convert glucose into ATP.

Chemical Reaction

Process of breaking and forming chemical bonds.

Mitotic Division

Process of cell division that produces new cells with identical DNA.

Organic Chemistry

Study of carbon-containing compounds.

Inorganic Chemistry

Study of compounds lacking carbon-hydrogen bonds.

Hydrogen Bonds (in Water)

Contribute to water's high surface tension.

Acid-Base Reaction

Reaction involving the transfer of H+ ions between reactants.