bio 18/25

Importance of Biological Research

• The significance of the content being studied in class lies in its real-world applications and ongoing research.

• Understanding genetics and molecular biology can lead to careers in research, impacting life-saving technologies like vaccines.

Insulin Gene Research

• The insulin gene is located on chromosome 11; this was established through extensive laboratory research.

• Research continues to evolve, highlighting that we don't know everything about genetics despite the foundational knowledge taught in school.

• Current research adapts with changes in funding and administrative focus, proving ongoing inquiry is essential.

mRNA and COVID-19 Vaccines

• The development of mRNA vaccines, such as for COVID-19, relies on foundational biological knowledge, showcasing important advances in medicine.

• Understanding the mechanisms behind these vaccines reinforces the importance of the material studied in class.

Gene Structure and Function

Structure of DNA

• DNA is structured as a double helix, with fundamental components:

  • Sugar-phosphate backbone on the outside.

  • Complementary base pairing at the center, which holds the two strands together.

  • Bases determine the gene sequence, critical for transcription.

Transcription Process

• The gene's base sequence in DNA dictates the RNA sequence during transcription:

  • Base Pairing Rule: A pairs with U (in RNA), and C pairs with G.

  • DNA is copied into mRNA, creating a new nucleic acid strand—RNA is not directly converted from DNA but generated as a separate molecule.

Transcription vs. Translation

• Transcription: Converts DNA to RNA (nucleic acids to nucleic acids).

• Translation: Converts mRNA to a protein (nucleic acids to amino acids), requiring a different language.

Protein Structure

• Proteins are made of 20 different amino acids, where amino acids are linked to form polypeptide chains:

  • Each amino acid has a corresponding codon in mRNA that determines its addition to the protein chain.

Ribosome Function

Ribosome Structure

• Ribosomes are key to protein synthesis, consisting of:

  • Large and small subunits made up of proteins and rRNA.

  • Ribosomes read mRNA from 5' to 3' and synthesize proteins by reading codons (sets of three bases).

Translation Process Steps

1. Initiation: Small ribosomal subunit binds to mRNA and recognizes the start codon (AUG) with the associated tRNA carrying methionine.

2. Elongation: The ribosome moves along the mRNA, matching tRNA anticodons to mRNA codons and forming peptide bonds between amino acids.

3. Termination: The process stops when the ribosome encounters a stop codon, which prompts the release factors to disassemble the translation machinery.

Translation Sites

• Ribosome has three sites crucial for translation:

  • A (Arrival) Site: Where tRNA with the next amino acid arrives.

  • P (Peptide) Site: Where the growing polypeptide chain is held and synthesized.

  • E (Exit) Site: Where uncharged tRNA exits the ribosome.

Genetic Code

• The genetic code consists of codons in mRNA, which map to specific amino acids.

• Understanding how to read the genetic code is essential for protein synthesis and application in biological research.

Summary Points

• Proteins are made of amino acids, dictated by mRNA codons.

• Ribosomes read codons to assemble proteins based on matching anticodons from tRNA.

• Key codons include the start codon (AUG, codes for methionine) and stop codons (do not code for amino acids).

• Ribosomes function as ribozymes due to their composition and catalytic activity in protein synthesis.