Unit 1
The Molecules and Chemical Reactions of Life

Overview

Biochemistry is an attempt to explain the chemical processes that characterize “life.” Generally, this attempt involves a study of biological molecules and the molecular reactions they undergo. The aim of this course is to provide you with the bridge between fundamental chemistry (elementary particles and chemical laws) and biology. It will also give you a sense of biochemistry as an ongoing field of research, by introducing you to the biochemical research literature. In Unit 1, we begin the bridging process. The unit is divided into five lessons:

  1. Introduction to Biochemistry
  2. The Cell
  3. Thermodynamics
  4. Water
  5. The Biochemical Research Literature

Objectives

After completing this unit, you should be able to

  1. define “biochemistry.”
  2. explain how the chemical properties of water make it the ideal biological solvent.
  3. describe the organization of a eukaryotic (nucleus-containing) cell, and compare it to the organization of a prokaryotic (non-nucleated) cell.
  4. name the major classes of biomolecules, and identify the atoms most commonly found in each class.
  5. define “metabolic pathway.”
  6. explain what is meant by “the biochemical literature,” and discuss why it is important for this (and other) biochemistry courses.
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Glossary

The characteristics of a good definition are that it identifies the thing described, and says something about where it is found and how it works. Each of the following definitions is incomplete. As you work through this and later units, you should develop a complete definition for the terms in each “Glossary.”

amphiphile molecule with both polar (or ionic) and nonpolar portions; most biomolecules are amphiphiles
anabolism biosynthetic reactions (i.e., synthesis)
ATP adenosine triphosphate, nucleotide that carries chemical energy in living organisms
biomolecule molecule of biochemical and biological importance
catabolism biochemical reactions (usually energy producing) in which larger molecules are broken down into smaller molecules
eukaryote cell which contains a nucleus and other membrane-enclosed organelles (103 − 106 times as large as a prokaryote)
Escherichia coli
(E. coli)		 typical, very well-studied prokaryote; a bacterium
functional group small reactive organic group attached to a larger molecule
heat of vaporization energy required to convert a liquid to a gas
hydrophile water soluble molecule
hydrophobe molecule which is not water soluble
law of mass action
Keq = [products]
[reactants]
  if one component changes (e.g., if product is removed) the other will change to keep the equilibrium constant ( Keq ) the same
organelle any membrane-enclosed structure in the cell that is designed to carry out a specific function
phylogeny evolutionary history of an organism or group of organisms
polar molecule molecule in which the bonding electrons are not shared equally between two atoms; the atom with the greater share of the bonding pair has a slight negative charge, the other atom a slight positive charge
polyprotic acid molecule with more than one ionizable acid group (e.g., a protein)
steady state chemical reaction in which formation and degradation of molecules are balanced
surface tension energy necessary to increase the surface area of a liquid
prokaryote unicellular organism without a nucleus
thermodynamics set of chemical laws which tell us whether a physical process is possible or not
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