Protein Synthesis Overview

Introduction

• Protein synthesis involves two main processes: transcription and translation.
• Transcription: Copying a single gene of DNA into mRNA.
• Translation: Using the mRNA strand to produce a protein.

Importance of Transcription and Translation

• DNA contains thousands of genes, each with a specific sequence of bases.
• Genes code for specific amino acids sequences that form proteins.
• DNA is located in the nucleus, but ribosomes (which read DNA to make proteins) are outside the nucleus.
• DNA is too large to leave the nucleus; thus, mRNA (a copy of a single gene) is used to transport genetic information to ribosomes.

Structure and Function of mRNA

• mRNA: Messenger RNA, a single gene copy.
• Differences from DNA:
  • Shorter (only one gene long).
  • Single-stranded.
  • Contains uracil (U) instead of thymine (T).

Transcription Process

1. Initiation: RNA polymerase binds to DNA just before the target gene.
2. Elongation:
   • DNA strands separate, exposing bases.
   • RNA polymerase reads DNA bases and creates complementary mRNA strand.
   • Complementarity: A-T (DNA), A-U (mRNA), C-G.
3. Termination: RNA polymerase detaches; DNA strands re-coil.

• The mRNA strand is now free to leave the nucleus.
• Template Strand: The DNA strand used to create mRNA.

Translation Process

• Inside ribosomes, mRNA is used to build proteins by reading codons (triplets of bases).
• Amino Acids: 20 different types used to form proteins.

Role of tRNA

• tRNA: Transfer RNA molecules bring amino acids to ribosomes.
• Each tRNA has:
  • An amino acid.
  • An anticodon (complementary to mRNA codon).
• Ensures correct amino acid sequence.

Ribosome Function

• mRNA binds to ribosome.
• tRNA delivers amino acids in order dictated by mRNA codons.
• Ribosome links amino acids to form a protein chain.
• Process continues until complete protein is formed.

Conclusion

• Protein synthesis is essential for converting genetic information into functional proteins.
• This video provided a detailed overview of the transcription and translation stages in protein synthesis.