Key Concepts in Genetic Information and Protein Synthesis

Genetic Code
  • Definition: A sequence formed by four bases of DNA: Adenine (A), Cytosine (C), Guanine (G), Thymine (T).
  • Triplet Codons: Groups of three nucleotides that code for one amino acid; proteins are made of amino acids linked in various arrangements.
  • Gene Function: Genes are sequences of DNA that encode the information for amino acid sequences in protein synthesis.
RNA Function
  • Role: RNA transfers information from DNA to the site of protein synthesis.
  • Synthesis: RNA is synthesized based on DNA templates.
Steps in Protein Synthesis
  1. Transcription: DNA is copied to form mRNA.
  2. Translation: mRNA is used to assemble proteins.
    • Each triplet codon corresponds to a specific amino acid.
    • There are 64 possible triplet codes; 61 specify amino acids, while 3 are stop signals.
Codons and Amino Acids
  • mRNA codons instruct the sequence of amino acids in proteins.
  • Example: AGC codes for Serine; UAA signals termination (stop codon).
Protein Secretion Process
  • Proteins destined for secretion have signal sequences that direct them to the endoplasmic reticulum.
  • Process:
    1. Synthesis in the ER.
    2. Transport to the Golgi apparatus.
    3. Final processing and packaging in vesicles.
    4. Exocytosis to release proteins into extracellular space.
Genetic Information Expression
  • Each cell contains 44 autosomes and 2 sex chromosomes.
  • Cells divide, replicating chromosomes ensuring identical DNA in daughter cells.
  • Cell differentiation is due to differential gene expression.
Cancer Characteristics
  • Definition: A genetic disorder caused by mutations in somatic cells leading to uncontrolled growth.
  • Oncogenes: Mutated genes that lead to cancer; cause continuous growth signals.
  • Tumor Types: Benign (localized) vs. Malignant (invasive).
  • Types of Cancer: Carcinomas (epithelial cells), Sarcomas (muscle cells), Lymphomas (white blood cells).
  • Carcinogens: Substances that increase the risk of cancer.
Genetic Engineering Techniques
  • Modification: Alteration of DNA base sequences by adding or deleting bases.
  • Techniques:
    • Restriction Nucleases: Cut DNA at specific sites.
    • Ligase: Links DNA fragments.
    • Transfection: Transfer of DNA between organisms, creating transgenic organisms.
    • cDNA Production: Using reverse transcriptase to create DNA copies without introns for bacterial expression.