Lecture Notes: The Process of Protein Synthesis in Human Cells

Basic Unit of Life

• Cell: Basic unit of all living tissue.
  • Contains a structure known as the nucleus.

Genetic Material in Cells

• Nucleus: Contains the genome.
• Genome: Split between 23 pairs of chromosomes in humans.
  • Chromosomes: Each contains a long strand of DNA.
  • DNA is tightly packaged around proteins called histones.

Genes and Protein Instructions

• Genes: Sections within the DNA.
  • Contain instructions for making proteins.

Transcription Process

1. Gene Activation:
   • An enzyme called RNA polymerase attaches to the start of the gene.
2. RNA Synthesis:
   • RNA polymerase moves along the DNA.
   • Creates a strand of messenger RNA (mRNA) from free bases in the nucleus.
   • The DNA code dictates the order of bases in mRNA.
3. Transcription:
   • Process of creating mRNA from DNA.

Messenger RNA Processing

• Post-Transcriptional Modifications:
  • mRNA undergoes processing (removal and addition of RNA sections).
• mRNA then moves from the nucleus to the cytoplasm.

Translation Process

1. Ribosome Binding:
   • Ribosomes in the cytoplasm bind to mRNA.
2. Protein Synthesis:
   • Ribosome reads the code in mRNA to produce an amino acid chain.
   • Amino Acids: 20 different types.
   • Transfer RNA (tRNA): Carries amino acids to the ribosome.
3. Codon Reading:
   • mRNA is read in triplets (codons).
   • tRNA delivers the corresponding amino acid for each codon.
4. Polypeptide Chain Formation:
   • Amino acids are added one by one to the growing chain.
   • Once complete, the chain folds into a 3D structure to form a protein.