Biology: Matter, Chemical Reactions, Water, and Macromolecules

Atom

The smallest unit of an element, consisting of protons, neutrons, and electrons.

Neutron

A subatomic particle found in the nucleus of an atom, with no electric charge.

Element

A pure substance made up of only one kind of atom.

Isotope

Forms of the same element that have a different number of neutrons.

Compound

A substance formed when two or more elements combine in a chemical reaction.

Covalent Bond

A chemical bond formed by the sharing of electrons between atoms.

Ionic Bond

A chemical bond formed through the transfer of electrons from one atom to another, resulting in charged ions.

Nucleus

The central part of an atom, containing protons and neutrons.

Electron

A negatively charged subatomic particle that orbits the nucleus of an atom.

Ion

An atom or molecule that has gained or lost one or more electrons, resulting in a net charge.

Molecule

A group of two or more atoms bonded together.

Chemical Reaction

A process that involves the rearrangement of the molecular or ionic structure of a substance.

Reactant

A substance that undergoes change during a chemical reaction.

Product

A substance that is formed as a result of a chemical reaction.

Activation Energy

The minimum energy required to initiate a chemical reaction.

Catalyst

A substance that increases the rate of a chemical reaction without being consumed in the process.

Enzyme

A biological catalyst that speeds up biochemical reactions by lowering the activation energy.

Substrate

The reactant on which an enzyme acts.

Active Site

The region of an enzyme where substrate molecules bind and undergo a chemical reaction.

Polar Molecule

A molecule with a partial positive charge on one end and a partial negative charge on the other end, resulting from unequal sharing of electrons.

Solution

A homogeneous mixture formed when a solute is dissolved in a solvent.

Acid

A substance that releases hydrogen ions (H+) into a solution.

Base

A substance that releases hydroxide ions (OH-) into a solution.

pH

A measure of the acidity or alkalinity of a solution, based on the concentration of hydrogen ions.

Buffer

A solution that resists changes in pH when small amounts of acid or base are added.

Hydrogen Bond

A weak bond formed between a hydrogen atom and an electronegative atom, such as oxygen or nitrogen.

Macromolecule

A large complex molecule, such as proteins, nucleic acids, carbohydrates, and lipids, essential for life.

Carbohydrate

Organic compounds made up of carbon, hydrogen, and oxygen, typically in a ratio of 1:2:1, serving as a major energy source.

Protein

A macromolecule composed of amino acids, essential for structure, function, and regulation of the body's tissues and organs.

Nucleic Acid

Biological macromolecules, such as DNA and RNA, that carry genetic information.

Polymer

A large molecule composed of repeating structural units (monomers) connected by covalent bonds.

Lipid

A group of organic compounds that are insoluble in water, including fats, oils, and steroids, important for energy storage and cell membrane structure.

Amino Acid

The building blocks of proteins, containing an amino group, a carboxyl group, and a unique side chain.

Nucleotide

The basic building block of nucleic acids, consisting of a sugar, a phosphate group, and a nitrogenous base.