D21 - Central Dogma Pt 2 Lecture Notes

Overview

This lecture continues the discussion on the central dogma of molecular biology, which describes the flow of genetic information within a biological system. It focuses primarily on the processes of transcription and translation.

Key Concepts

Central Dogma of Molecular Biology

• Explains the flow of genetic information.
• Processes involved: DNA → RNA → Protein.

Transcription

• The process by which the information in a strand of DNA is copied into a new molecule of messenger RNA (mRNA).
• Steps involved:
  • Initiation: RNA polymerase binds to a specific region called the promoter.
  • Elongation: RNA polymerase moves along the DNA template, adding RNA nucleotides in the 5’ to 3’ direction.
  • Termination: RNA polymerase reaches a terminator sequence, and transcription stops.
• mRNA is processed before translation (splicing, capping, and polyadenylation).

Translation

• The process by which mRNA is decoded to produce a specific polypeptide or protein.
• Occurs in the ribosome, which facilitates the binding of transfer RNA (tRNA) to mRNA.
• Steps involved:
  • Initiation: Small ribosomal subunit binds to the start codon on the mRNA.
  • Elongation: tRNAs bring amino acids to the ribosome in sequence dictated by the mRNA.
  • Termination: A stop codon is reached, and the polypeptide is released.

Important Enzymes and Molecules

• RNA Polymerase: Enzyme responsible for synthesizing RNA from a DNA template.
• Ribosome: Molecular machine that facilitates the translation of mRNA into protein.
• tRNA (Transfer RNA): Brings amino acids to the ribosome during translation.
• mRNA (Messenger RNA): Carries the genetic information from DNA for protein synthesis.

Post-Translational Modifications

• Processes that modify the newly synthesized proteins, affecting their function and activity.
• Types include phosphorylation, glycosylation, and ubiquitination.

Summary

The central dogma outlines the fundamental framework for genetic information flow: DNA is transcribed into RNA, which is then translated into protein. This process is essential for the expression of genes and the functioning of all cells. Understanding these processes provides insights into genetic regulation and expression.