Biology - The Chemistry of Life

Atom

The smallest unit of matter that still retains the properties of an element

Element

A substance made up of only one type of atom

Molecule

Two or more atoms joined together

Compound

A molecule made up of two or more different elements in a fixed ratio

Macromolecule

Very large molecules, often polymers

Proton

A positively charged particle found in the nucleus

Electron

A negatively charged particle that moves around the nucleus

Neutron

A neutrally charged particle found in the nucleus

Valence Electron

An electron in the outermost shell that determines the reactivity of an atom

Ionic Bond

A bond formed when one atom transfers electrons to another

Covalent Bond

A bond formed when atoms share electrons

Polarity

An uneven distribution of electrical charge within a molecule

Van der Waals Forces

Weak attractions caused by temporary charges between molecules

Cohesion

Water molecules sticking to each other

Adhesion

Water sticking to other substances

pH Scale

Measures acidity or basicity from 0–14; each whole number represents a tenfold change

Buffer

A substance that resists changes in pH

Carbohydrates

Simple sugars used for quick energy

Lipids

Fats and oils used for long-term energy storage

Proteins

Made of amino acids; used for muscle construction and enzymes

Nucleic Acids

DNA and RNA; store genetic information

Reactants

Starting substances in a chemical reaction

Products

Substances formed during a chemical reaction

Activation Energy

The minimum amount of energy required to start a chemical reaction

Enzyme

A biological catalyst (usually a protein) that lowers activation energy

What is an atom made of?

Protons (+), neutrons (neutral), and electrons (−)

Difference between ionic and covalent bonds

Ionic bonds transfer electrons; covalent bonds share electrons

What is polarity?

An uneven distribution of electrons that creates partial charges

How does polarity relate to water?

It causes cohesion between water molecules and adhesion to other substances

Solution

A mixture where a solute dissolves in a solvent

Solute

The substance being dissolved

Solvent

The substance doing the dissolving

Solution vs Suspension

A solution fully dissolves; a suspension does not

What does the pH scale measure?

The acidity or basicity of a substance

Why is the pH scale not linear?

Each whole number is ten times more acidic or basic than the previous

Function of carbohydrates

Quick energy

Function of lipids

Long-term energy storage

Function of proteins

Muscle building and enzymes

Function of nucleic acids

Storing genetic information (DNA and RNA)

Simple sugar belongs to which biomolecule?

Carbohydrates

Amino acids belong to which biomolecule?

Proteins

Nucleotides belong to which biomolecule?

Nucleic acids

What happens to atoms in a chemical reaction?

Atoms rearrange but the number and type stay the same

Exothermic reaction

A reaction that releases heat

Endothermic reaction

A reaction that absorbs heat

Relationship between catalyst, enzyme, and protein

Enzymes are usually proteins that act as catalysts