Biochemistry Lecture: Part Two

Focus on Processes

• Transition from biological molecules to processes connecting nucleic acids and proteins.
• Examines gene expression or protein synthesis, known as the central dogma of biology.
• DNA holds heritable instructions for building proteins and organisms.

Key Concepts

• Gene: Portion of DNA coding for a protein, sometimes multiple proteins.
• Central Dogma: DNA -> RNA -> Protein.
• Transcription: DNA to RNA conversion.
• Translation: RNA to protein conversion.

Process Insights

• All cells have the same DNA but different proteins are expressed in different cells leading to diverse cell types.
• Example: Different proteins in nerve cells, blood cells, cheek cells, and sperm cells, each specialized for distinct functions.
• Analogy: DNA as a cookbook, cells only "make" what's needed, not every possible protein.

Nucleic Acids and Proteins

• DNA stores long-term information, RNA is a temporary form used to build proteins.
• Generally, information flows DNA -> RNA -> Protein, with exceptions in some viruses.

Detailed Steps in Protein Synthesis

• Transcription: Occurs in the nucleus, RNA polymerase creates mRNA from DNA.
• RNA Processing: In eukaryotes, involves adding a GTP cap and poly-A tail, and removing introns.
• Translation: mRNA directs tRNA to bring amino acids to ribosomes to build proteins.
• Codons on mRNA are read in threes and correspond to specific amino acids.

Special Notes

• Eukaryotes (with a nucleus) have a different process than prokaryotes (without a nucleus).
• Prokaryotes perform transcription and translation in the same space.
• Codon charts help determine which amino acids correspond to mRNA sequences.

Practice and Application

• DNA sequences are converted to RNA before protein synthesis begins.
• Familiarity with the genetic code and codon chart is essential.

Conclusion

• Protein synthesis involves transcription, RNA processing (in eukaryotes), and translation.
• Proteins have specific shapes essential for their function, relying on proper amino acid sequence.
• Understanding protein synthesis is crucial for grasping how genetic information translates into functional proteins.