Biochemistry Key Concepts: Atoms, Molecules, and Macromolecules chap 2

Biochemistry

The study of the chemical processes and substances associated with living organisms; this chapter is titled Biochemistry.

Atom

The smallest unit of an element (pure substance of matter).

Proton

A positively charged (+) particle in an atom.

Neutron

A neutral particle in an atom.

Electron

A negatively charged (-) particle in an atom.

Protons

Normally remain constant in an atom.

Neutrons

Can vary/change in an atom.

Electrons

Can vary/change in an atom.

Normal atom charge

The charges normally balance.

Valence electrons

Electrons in the outermost electron shell; the slides identify number of valence electrons as a property of atoms.

Electron shells

Regions/shells containing electrons; the slides identify number of electron shells as an atomic property.

Ion

A charged atom.

Cation

A positively charged ion.

Anion

A negatively charged ion.

Isotope

An atom of an element that has a different number of neutrons.

Molecule

Two or more atoms bound together.

Molecular formula

A notational description of a molecule's components.

Organic molecule

A molecule in which carbon (C) and hydrogen (H) are present.

Inorganic molecule

A molecule in which carbon (C) and hydrogen (H) are absent.

Compound

A molecule that contains more than one element.

Isomer

Molecules with the same formula but different structures.

Functional groups

Molecules/groups with shared chemical properties; they are common in biochemical reactions and typically react in similar ways.

Solute

The substance being dissolved.

Solvent

The substance doing the dissolving.

Solution

A liquid mixture of solute and solvent.

Acid

A substance that increases the hydrogen ion (H+) concentration of a solution.

Example of an acid reaction

HCl → H+ + Cl-.

Base

A substance that reduces the hydrogen ion (H+) concentration of a solution.

Example of a base reaction

NH3 + H+ → NH4+.

pH

The negative logarithm of the hydrogen ion concentration of a solution.

pH scale

The scale used to describe solutions because it is logarithmic and uses convenient numbers from 0-14.

Acidosis

Low blood pH.

Alkalosis

High blood pH.

Buffer

A substance that releases or absorbs H+ ions to stabilize pH.

Ionic bond

Electrons are pulled from one atom; there is no sharing of the electrons.

Electrolyte

An ion in solution.

Nonpolar covalent bond

Atoms share valence electrons and have the same electronegativities.

Polar covalent bond

Atoms share valence electrons but have different electronegativities.

Hydrogen bond

Hydrogen atoms are attracted to an electronegative atom.

Van der Waals forces

Regions of electronegative atoms are attracted to one another.

Hydrophilic

A substance that maximizes contact with water.

Hydrophobic

A substance that minimizes contact with water.

Catalyst

A substance that increases the rate of a reaction.

Enzyme

A protein that acts as a catalyst.

Synthesis reaction

A reaction in which two or more reactants combine to make a larger product.

Decomposition reaction

A reaction in which a substance is broken down into smaller components.

Exchange reaction

A reaction in which molecules swap components.

Endergonic reaction

A reaction that requires an energy investment to create products with higher final energy.

Exergonic reaction

A reaction that creates products with lower final energy than the reactants.

Macromolecule

A very large molecule.

Four major macromolecule groups

Carbohydrates, proteins, lipids, and nucleic acids.

Monomer

A building block or repeating unit of molecules.

Polymer

A chain of repeating monomers.

Carbohydrates

Sugars; one of the four major macromolecule groups.

Carbohydrate monomer

Monosaccharides; glucose is the most common example given.

Carbohydrate polymer

Polysaccharides.

Cellulose

Strengthens cell walls in plants.

Starch

Stores energy in plants.

Glycogen

Stores energy in animals.

Chitin

Strengthens exoskeletons of insects and fungi.

Lipids

Fats; one of the four major macromolecule groups.

Proteins

One of the four major macromolecule groups.

Nucleic acids

One of the four major macromolecule groups.