BIOL 231 Study Guide Notes

Knowledge and Analytical Skills for BIOL 231

Salmonella typhimurium and the Ames Test

• Biological Significance: Understand the role of Salmonella typhimurium in the Ames test.
• Importance of his genes: Know why the his genes are crucial for the Ames test.
• Ames Test Mechanism: Describe how the Ames test works to identify potential mutagens.

Molecular Biology Essentials

• Common Cells and Enzymes: Familiarize yourself with the types of cells and enzymes, like host cells and restriction enzymes, frequently used in molecular biology.

Dilutions

• Dilution Problems: Solve dilution problems starting from stock solutions.

Aseptic Techniques

• Reasons for Aseptic Techniques: Understand why aseptic techniques are essential when working with bacteria, nucleic acids, or proteins to prevent contamination.

Pipetting

• Proper Use of Pipettors and Micropipettors: Demonstrate the correct use of pipettors and micropipettors.
• Handling Errors: Identify handling errors that can lead to dispensing incorrect volumes.

Agar in Bacteriological Media

• Purpose of Agar: Explain the purpose of using agar in bacteriological media as a solidifying agent.

Micropipettor Accuracy

• Micropipettor Accuracy and Error:
  • Micropipettors are not perfectly accurate; suppliers provide accuracy and precision data.
  • Example: A 0.5-10 μl micropipettor has an accuracy of ±0.1 μl.
  • Percent Error Calculation:
    • Pipetting 10.0 μl: $\frac{0.1 \mu l}{10.0 \mu l} \times 100 = 1\%$
    • Pipetting 0.5 μl: $\frac{0.1 \mu l}{0.5 \mu l} \times 100 = 20\%$

DNA Purification from Bacteria

• Process of DNA Purification: Describe the process of purifying DNA from bacteria.
• Role of Reagents: Understand the role and properties of each reagent:
  • EDTA: Chelates divalent cations, inhibiting DNases.
  • SDS (Sodium Dodecyl Sulfate): A detergent that lyses cells and denatures proteins.
  • Phenol: Denatures and separates proteins from DNA.
  • Chloroform: Further denatures and removes proteins.
  • Alcohol (Ethanol or Isopropanol): Precipitates DNA.
  • Proteinase K: Digests proteins.
  • RNAse A: Degrades RNA.
• Cell Components After Centrifugation: Know which cell components appear in each layer of the centrifuge tube after centrifugation.

Genomic vs. Plasmid DNA Isolation

• Similarities and Differences: Compare and contrast the processes of isolating genomic DNA and plasmid DNA from bacteria.

Spectrophotometry

• Spectrophotometer Use: Know the purpose of using a spectrophotometer.
• Absorbance Information:
  • A260 nm: Indicates the concentration of nucleic acids.
  • A260 nm/A280 nm Ratio: Assesses the purity of DNA; a ratio of ~1.8 is generally accepted as