Transcription

Microbial Genetics

• Introduction to Microbial Genetics

  • Focus on the need for protein synthesis.

  • Central theme is the process of translating genetic information into functional proteins.

Central Dogma of Molecular Biology

• Explains the flow of genetic information within a biological system.

• Sequence: DNA → RNA → Protein.

Step 1: Initiation

• RNA pol attaches nonspecifically to the DNA.

• RNA pol travels down the DNA until it identifies the promoter region.

• The sigma factor (σ) enhances promoter recognition in bacteria.

• RNA pol begins to unwind DNA beginning at the promoter

Step 2: Elongation

• RNA polymerase aligns complementary RNA bases, creating a long strand of mRNA

  • No primer is needed for RNA synthesis.

Step 3: Termination

• Termination of transcription can occur via two mechanisms:

  • Rho-independent termination:

    • G-C rich hairpin loop forms, creating tension in the mRNA and causing RNA polymerase to pop off

  • Rho-dependent termination:

    • Rho protein pushes between pol & DNA causing RNA to pop off

Summary of the Central Dogma

• Provides insight into how proteins are made from genetic information.

  • The overall pathway is:

  • DNA → Transcription (RNA) → Translation (Proteins).

Key Terms

• RNA polymerase: Enzyme responsible for synthesizing RNA from a DNA template.

• Sigma factor: Protein needed for the initiation of transcription in bacteria.

• mRNA (Messenger RNA): Carrier of genetic information from DNA to ribosomes for protein synthesis.