Central Dogma of Molecular Biology

Introduction

• Body as a bustling city with billions of cells working continuously.
• Central dogma as the command center with fundamental principles guiding genetic information flow.

What is the Central Dogma?

• Describes the flow of genetic information in biological systems:
  • DNA → RNA → Proteins
• Two main processes:
  • Transcription
  • Translation

Historical Context

• Proposed by Francis Crick in 1958.
  • Following DNA’s structure discovery by Watson and Crick in 1953.
• Clarified how genetic information is transferred within biological systems.

Steps in the Central Dogma

1. Transcription

• Process of creating RNA from DNA.
• Enzyme RNA polymerase reads DNA and synthesizes mRNA (messenger RNA).
• DNA serves as a blueprint locked in the nucleus, while RNA copies it to function in the cytoplasm.

2. Translation

• Process where mRNA is decoded to produce proteins.
• Occurs in the ribosome (protein factory) within the cytoplasm.
• Codons: Sets of three nucleotides on mRNA that specify amino acids.
• tRNA (transfer RNA) brings corresponding amino acids, ensuring correct sequence assembly.
• Proteins fold into specific shapes essential for their function.

Importance of Directionality in Translation

• Translation follows a specific direction (5' to 3') to maintain the correct amino acid sequence.
• Changing the reading frame results in malformed proteins, impacting functionality.

Gene Expression

• Turning on genes to create proteins, influencing cell function and environmental response.
• Cell regulation determines which genes are expressed and when.

Exceptions to the Central Dogma

• RNA Splicing: Removal of introns and joining of exons to create mRNA variants.
• Epigenetic Modifications: Changes in gene expression without altering DNA sequence; influenced by environment (e.g., methylation, histone modification).
• Reverse Transcription: Some viruses like HIV synthesize DNA from RNA, contradicting the typical DNA to RNA flow.

Conclusion

• The central dogma serves as a foundational principle in molecular biology, guiding research and understanding of genetics and diseases.

Next Steps

• Importance of taking notes to retain the information learned.
• Encourage use of fun stationery products to enhance studying.