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Lecture on RNA Transcription Process

Jul 16, 2024

Lecture on RNA Transcription Process

Introduction by the Teacher

  • Good evening and greetings.
  • Addresses why the teacher is taking the class again тАУ commitment to studentтАЩs success.
  • Emphasizes the teacherтАЩs dedication: whether itтАЩs YouTube, special classes, or plus classes, the teacher will always support the students.

The Objective of Teaching

  • Aim to produce maximum doctors possible.
  • Open to teaching both free and paid platforms.
  • Focus on maximizing studentsтАЩ potential.

The Process of Transcription

Replication vs Transcription

  • Previously discussed DNA replication.
  • TodayтАЩs focus: DNA to RNA (Transcription)

Key Requirements for Transcription

  • DNA Template: Source guide for RNA synthesis.
  • RNA Polymerase: Enzyme that reads DNA and assembles RNA sequence.
  • Nucleoside Triphosphates (NTPs): The building blocks for RNA.
  • Mg2+ and Mn2+ ions: Essential for polymerization activity.
  • Sigma (╧Г) Factor: Initiates transcription by recognizing the promoter region.
  • Rho (╧Б) Factor: Involved in termination of transcription.

Detailed Steps of Transcription

Initiation

  • Sigma Factor helps RNA Polymerase to bind to DNA promoter region.
  • Without sigma factor, RNA polymerase cannot recognize where to begin.

Elongation

  • Sigma factor detaches after initiation.
  • RNA polymerase continues to elongate RNA strand using DNA template.
  • RNA is synthesized in the 5тАЩ to 3тАЩ direction.
  • Formation of a temporary DNA-RNA hybrid.

Termination

  • Rho Factor helps terminate transcription by breaking DNA-RNA hybrid.

Prokaryotic vs Eukaryotic RNA Polymerase

Prokaryotic Details

  • Single type of RNA polymerase for all types of RNA synthesis.
  • RNA Polymerase is composed of several subunits: alpha (2), beta, beta prime, omega, and sigma.
  • Total: 5 different types of polypeptide subunits.

Eukaryotic Details

  • Three types of RNA polymerases:
    • RNA Polymerase I: Synthesizes rRNA (5.8S, 18S, 28S).
    • RNA Polymerase II: Synthesizes mRNA.
    • RNA Polymerase III: Synthesizes tRNA & 5S rRNA.
  • Transcription occurs in the nucleus, translation in the cytoplasm.

Post-Transcriptional Modifications in Eukaryotes

  • Splicing: Removing introns (non-coding regions).
  • 5тАЩ Capping: Adding a 7-methylguanosine cap.
  • 3тАЩ Polyadenylation: Adding poly(A) tail.
  • Protections ensure mRNA stability and help in translation initiation.
  • mRNA must travel from nucleus to cytoplasm for translation; thus, modifications protect mRNA during its journey.

Differences in Prokaryotic Transcription

  • Transcription and translation are coupled in prokaryotes (occur in the same location).

Conclusion

  • Understanding transcription mechanisms is crucial because of their significance in gene expression and regulation.
  • Emphasizes the importance of consistency in learning and utilizing provided resources effectively (e.g., class notes, books).

Next Steps:

  • Continue with Genetic Code and further details in the next class.
  • Importance of continuous learning and student engagement.

Commitment to Learning:

  • Reminds students to remain consistent and diligent.
  • Notes will be provided via the class telegram group.

Take Care & Sign Off:

  • End of the session with encouragement for student success.

Full transcript