Notes on Protein Synthesis

Introduction to Protein Synthesis

• Definition: Protein synthesis is the process of making proteins.
• Two main steps:
  • Transcription: Copying DNA into mRNA.
  • Translation: Using mRNA to produce proteins.

Importance of Protein Synthesis

• Location: Genetic material (DNA) stored in the nucleus of cells.
• Function of DNA: Contains thousands of genes, each coding for specific amino acid sequences to form proteins.
• Ribosomes: Structures outside the nucleus that read mRNA to synthesize proteins.
• Limitation of DNA: DNA is too large to leave the nucleus, necessitating the creation of mRNA copies.

mRNA Characteristics

• Definition: Messenger RNA (mRNA) is a copy of a single gene.
• Differences from DNA:
  • Length: mRNA is shorter because it represents only a single gene.
  • Structure: mRNA is single-stranded, whereas DNA is double-stranded.
  • Base substitution: Thymine (T) in DNA is replaced with Uracil (U) in mRNA.

Transcription Process

1. Initiation: RNA polymerase binds to DNA at the start of the gene.
2. Separation: DNA strands uncoil and separate, exposing bases.
3. Base Complementarity: RNA polymerase reads DNA bases and adds complementary mRNA bases (e.g., A pairs with U, C with G).
4. Assembly: mRNA is built base by base as RNA polymerase moves along the DNA.
5. Completion: Once the entire gene is transcribed, RNA polymerase detaches and the DNA strand closes.
6. Template Strand: The strand used for mRNA synthesis is referred to as the template strand.

Genetic Code and Codons

• Triplets/Codons: Groups of three bases on mRNA representing specific amino acids.
• Amino acids: 20 types used to build proteins, each corresponding to a specific codon.
  • Example: AGU codes for serine, CCA codes for proline.

Translation Process

1. Binding: mRNA binds to the ribosome.
2. tRNA Role: Transfer RNA (tRNA) brings amino acids to the ribosome.
   • tRNA has an anticodon that is complementary to the mRNA codon.
3. Complementarity: Each tRNA carries a specific amino acid related to its anticodon (e.g., UCA brings serine for AGU).
4. Amino Acid Chain Formation:
   • Ribosome joins amino acids in the order specified by mRNA codons.
   • Ribosome moves along mRNA, allowing new tRNA molecules to bring in more amino acids.
5. Completion: Once the ribosome reaches the end of the mRNA, the completed amino acid chain detaches.
6. Protein Folding: The amino acid chain folds to form a functional protein.

Conclusion

• Summary of the key processes involved in protein synthesis.
• Encouragement to like and subscribe for more educational content.