Lecture Notes: Protein Synthesis

Overview

• Protein Synthesis: Process of making proteins, involves two main steps:
  • Transcription
  • Translation

Importance of Protein Synthesis

• DNA: Contains all genetic material in the nucleus, essential for controlling cell functions.
• Genes: Sections of DNA with specific sequences of bases that code for amino acids forming proteins.
• Ribosomes: Structures outside the nucleus that read DNA to create proteins.
• mRNA: Messenger RNA, a copy of a gene, can leave the nucleus to reach ribosomes for protein synthesis.

Transcription

Basics

• Conversion of a DNA gene into mRNA.
• mRNA Structure:
  • Shorter, single-stranded compared to DNA.
  • Contains Uracil (U) instead of Thymine (T).

Process

1. DNA uncoils for transcription.
2. RNA Polymerase: Enzyme binds to DNA and separates strands.
3. RNA Polymerase reads DNA bases and creates complementary mRNA bases:
   • C pairs with G, T pairs with A, A pairs with U.
4. DNA strands rejoin post-transcription.
5. The mRNA strand leaves the nucleus to the ribosome.

Translation

Basics

• mRNA used to produce a protein.
• Codons: Triplets of bases on mRNA that code for specific amino acids.

Process

1. mRNA binds to ribosome.
2. tRNA (Transfer RNA): Brings specific amino acids to ribosome:
   • Contains an anticodon complementary to mRNA codon.
3. Ribosome reads mRNA codons:
   • Ensures correct amino acids are added in sequence.
4. Amino acids are joined to form a polypeptide chain.
5. Chain folds into a functional protein.

Key Points

• Each amino acid is coded by a unique triplet/codon.
• Translation builds a protein by sequentially adding amino acids.

Conclusion

• Protein synthesis is crucial for cell function.
• Understanding transcription and translation helps in grasping how proteins are made and function in organisms.