Protein Synthesis

Protein synthesis is the process of creating proteins through two main steps: transcription and translation.

Importance of Protein Synthesis

• DNA in the Nucleus:
  • DNA contains all genetic material in the form of thousands of genes.
  • Each gene is a sequence of bases that codes for specific amino acids forming proteins.
• Role of Ribosomes:
  • Proteins are synthesized by ribosomes located outside the nucleus.
  • DNA is too large to exit the nucleus, necessitating the creation of a smaller copy (mRNA).

Transcription

• Definition:
  • Transcription is copying a single gene from DNA into mRNA.
• Characteristics of mRNA:
  • Shorter than DNA: Represents a single gene.
  • Single-stranded: Unlike the double helix structure of DNA.
  • Base Pair Differences: Contains uracil (U) instead of thymine (T).

Transcription Process

• Uncoiling DNA:
  • DNA is normally a double helix; for transcription, it is uncoiled.
• RNA Polymerase Role:
  • Binds to DNA before the gene starts.
  • Separates strands and reads bases to build mRNA.
• Complementary Base Pairing:
  • mRNA bases pair with DNA as follows:
    • A (DNA) → U (mRNA)
    • T (DNA) → A (mRNA)
    • C (DNA) → G (mRNA)
    • G (DNA) → C (mRNA)
• Template Strand:
  • The strand of DNA used by RNA polymerase to create mRNA.

Translation

• mRNA Role:
  • mRNA leaves the nucleus to the ribosome for translation.
• Codons and Amino Acids:
  • mRNA and DNA each have triplets of bases called codons.
  • Each codon codes for a specific amino acid.

Translation Process

• Binding of mRNA and Ribosome:
  • mRNA binds to ribosome to initiate protein synthesis.
• tRNA's Role:
  • Carries amino acids to the ribosome.
  • Has an anticodon complementary to mRNA codon.
• Building Protein:
  • tRNA ensures correct amino acids are added in sequence.
  • Ribosome joins amino acids to form a polypeptide chain.
  • Process repeats until the entire mRNA is translated.
• Final Steps:
  • Amino acid chain detaches and folds into a functional protein.

Conclusion

• Synthesis involves the coordination of mRNA, ribosome, and tRNA to create proteins essential for cellular function.

Note: This summary is based on a video presentation on protein synthesis, highlighting the crucial steps and mechanisms involved in synthesizing proteins from DNA instructions.