6.3 Transcription and RNA Processing

• mRNA (Messenger RNA):

  • Transcribed from DNA and carries genetic information from DNA to the ribosome
  • Codes for the specific amino acid sequence of a protein
  • Structure of mRNA molecule plays a role in determining its function
• tRNA (Transfer RNA):

  • Small molecules that function in protein synthesis
  • Have specific binding sites for specific amino acids
  • Have an anticodon sequence that base pairs with the codon sequence of the mRNA
  • Structure of tRNA molecules, including the L-shaped conformation, plays a role in their function
• rRNA (Ribosomal RNA):

  • Most abundant type of RNA in cells
  • Functional building blocks of ribosomes
  • Form the structural backbone of the ribosome
  • Interact with mRNA and tRNA molecules during translation process
  • Sequence and structure of rRNA molecules are important for their function
• Central Dogma of Molecular Biology:

  • Genetic information flows from DNA to protein
  • Process involves transcription of DNA into mRNA
  • mRNA carries genetic information that codes for the specific amino acid sequence of a protein
  • Translation of genetic information into a protein occurs on the ribosome
• RNA Polymerase:

  • Enzyme that catalyzes the transcription process
  • Binds to a specific region of DNA called the promoter
  • Reads the DNA sequence and synthesizes a complementary RNA strand
  • Uses a single strand of DNA (template strand) to determine the sequence of bases in the newly formed RNA molecule
• Processing the mRNA Transcript:

  • Addition of a poly-A tail to the 3' end of the mRNA transcript
  • Addition of a 5' cap to the 5' end of the mRNA transcript
  • Excision of introns and splicing of exons to generate a mature mRNA molecule
  • Alternative splicing can generate different versions of mRNA molecules, increasing protein diversity