Nucleic Acid Extraction Methods 100-116

Chapter 3 Nucleic Acid Extraction Methods Outline

Measurement of Nucleic Acid Quality and Quantity

  • Electrophoresis: Used for analyzing nucleic acid quality

  • Spectrophotometry: Measures nucleic acid concentration by absorbance

  • Fluorometry: Sensitive measurement of nucleic acids' concentrations

Isolation of DNA

Preparing the Sample

  • Techniques for lysis of cellular material to extract DNA

  • Bacteria and Fungi: Requires breaking tough cell walls using enzymatic or mechanical methods

  • Viruses: Viral DNA isolation is often from cell-free specimen sources

  • Nucleated Cells in Suspension (Blood and Bone Marrow): Focused on white blood cells during collection to isolate DNA

  • Plasma and Tissue Samples: Various approaches based on starting materials

DNA Isolation Chemistries

  • Organic Isolation Methods: Involves phenol/chloroform extraction

  • Inorganic Isolation Methods: "Salting out" techniques don’t use organic solvents

  • Solid-Phase Isolation: Uses silica columns for binding and purification

Objectives

  1. Compare and contrast organic, inorganic, and solid-phase isolation methods

    • Solid-phase methods are more rapid than traditional techniques.

    • Organic techniques may yield higher purity but involve hazardous chemicals.

  2. Describe DNA isolation methods from minimal and challenging samples

  3. Compare and contrast RNA isolation approaches: organic vs. solid-phase

  4. Understand the distinction between total RNA and messenger RNA isolation

  5. Explain methods for determining quality and quantity of DNA and RNA preparations

  6. Calculate yield and concentration based on nucleic acid preparations

Isolation of RNA

Total RNA Extraction

  • Collection and preservation are critical due to RNA's instability

  • Specimen Collection: Avoid RNase contamination

RNA Isolation Chemistries

  • Organic Isolation: Similar to DNA, using strong denaturants for RNA stability

  • Solid-Phase Isolation: Utilizes silica for effective RNA capture

Isolation of polyA (Messenger) RNA

  • Requires enrichment protocols due to low abundance in total RNA

Measurement of Nucleic Acid Quality and Quantity

Electrophoresis

  • Visual quality assessment; uses dyes for DNA/RNA visibility

  • Distinction of RNA presence indicated by ribosomal bands

Spectrophotometry

  • Measurements at 260 nm for nucleic acid concentration

  • Purity checked via A260/A280 ratios

Fluorometry

  • Uses fluorescent dyes specific to nucleic acids for sensitive quantification

Advanced Concepts

  • Microfluidics: Emerging technology for nucleic acid analysis with low sample volume requirements

  • Importance of preventing contamination in RNA and DNA analyses, particularly for high-quality results.