Introduction to Molecular Biology

Molecular Biology is the science that aims to understand biological activity at the molecular level. These biological activities usually involve the plant or animal cell, and the nucleic acids and proteins that are at work within the cell.  Molecular Biologists use some standard techniques that have been optimized over many years. These basic techniques can also be employed by scientists from many different areas of research and applied science.

The following is a free guide that introduces these classic molecular biology techniques (for bacteria, unless otherwise noted). Through each workflow, we provide background information, protocols, references to peer-reviewed literature, and help selecting reagents for your application.  Protocols for the use of a specific product are still available on the product pages. This guide to Molecular Biology is brought to you free by Sigma Life Science.

Sigma has also developed many other resources you may find helpful:

Synthetic Biology Resources - a collection of articles, posters and reviews. Also find links to the synthetic biology community and some great free tools.

Cell Culture Manual - A manual covering the basics of eukaryotic cell culture. Introduction to basic techniques, protocols, and product selection guides all in one place.

qPCR Technical Guide - A guide to understanding qPCR, designing probes and primers, optimizing and troubleshooting your assays.

Molecular Cloning for Protein Expression

The aim of molecular cloning is to insert the gene-of-interest (GOI) into a plasmid vector. This vector is then inserted into a cell that will express the protein encoded by the GOI. Once protein is expressed, the protein function can be studied as it affects the cell signaling, morphology or other aspects. Alternatively, the protein can be expressed in large quantities that can then be studied directly with other techniques.

General Information
Introduction to Expression Systems  
Troubleshooting Guide
Molecular Cloning
Cloning Manual (provided by Oxford Genetics)
SnapFast™ Vector Selection Charts
SnapFast™ Vector Selection Guide
Introduction to Restriction Enzymes
Restriction Enzyme Protocols
Introduction to Bacterial Transformation
Introduction to Yeast Transformation
Introduction to Blue-white Screening
Competent Cell Selection Guide
Transformation Protocols for Bacteria
Transformation Protocols for Yeast
Microbial Culture
Introduction to Bacterial Culture
Introduction to Yeast Culture
Bacterial Culture Protocols
Yeast Culture Protocols
Nucleic Acid Purification
Introduction to Nucleic Acid Purification
Nucleic Acid Purification Kit Selection Guide
  Introduction to Transfection
X-tremeGENE(TM) Transfection Database
X-tremeGENE(TM) General Recommendations
Transfection Reagent Selection Guide
Lipid Reagent Optimization Protocol
Best Practices of Transfection

Expression Analysis

Whole cell lysates, as well as purified samples, can be further analyzed using gel electrophoresis to separate the components of the sample based on size, followed by blotting which detects a specific protein or nucleic acid using antibodies or nucleic acid probes. Finally, the probe or antibody signal can be detected and compared among the samples.

Nucleic Acid Electrophoresis
Protein Electrophoresis
Introduction to Nucleic Acid Electrophoresis
Introduction to Markers & Ladders
Markers & Ladders Selection Guide
Introduction to Protein Electrophoresis
Hybridization (Northern/Southern) Western Blotting
Introduction to Hybridization Introduction to Western Blotting
Signal Detection
  Introduction to Detection Methods