Protein Synthesis

Protein Synthesis Overview

  • Definition: Protein synthesis is the process by which cells build proteins, crucial biomolecules for structural and functional purposes in organisms.

Importance of Proteins

  • Biomolecule Role: Proteins build tissues and structures in living organisms.

  • Composition: Made from long chains of amino acids, known as polypeptides.

    • Peptide: A chain of amino acids.

Locations of Protein Synthesis

  • Eukaryotic Cells:

    • Transcription occurs in the nucleus, where DNA is copied to mRNA.

    • Translation occurs in the cytoplasm, where mRNA is translated into proteins by ribosomes.

  • Prokaryotic Cells: Lacks a defined nucleus; both transcription and translation occur in the cytoplasm.

Central Dogma of Molecular Biology

  • Describes the flow of genetic information as:

    • DNA -> mRNA (transcription)

    • mRNA -> Protein (translation)

Genetic Code and Genes

  • DNA Functionality: Contains information dictating traits, such as eye color and blood type.

  • Genes: Segments of DNA that code for proteins, responsible for producing mRNA during transcription.

  • mRNA: Essential for translating genetic code into proteins.

Process of Transcription

  • Definition: Transcription is where genetic information from DNA is converted into messenger RNA (mRNA).

  • RNA Differences: RNA contains uracil (U) instead of thymine (T) found in DNA.

  • Key A-Pairs:

    • A (Adenine) pairs with U (Uracil)

    • C (Cytosine) pairs with G (Guanine)

Translation Process

  • Translation Overview: mRNA links with ribosomes, directing transfer RNA (tRNA) to align amino acids based on codons.

    • tRNA Role: Delivers specific amino acids to the ribosome based on the sequence of codons in mRNA.

  • Peptide Bonds: Amino acids are joined together via peptide bonds to form proteins.

  • Post-Translation: tRNA returns to pick up additional amino acids for further protein synthesis.

Codon Charts and Amino Acids

  • Using Codon Charts: Essential for decoding mRNA sequences into amino acids.

  • Reminder: RNA uses uracil (U), not thymine (T).