Lecture on Translation in Biology
Overview
- Translation is the process of synthesizing proteins from RNA transcripts.
- It involves interpreting the genetic code to produce a specific polypeptide.
Genetic Code
- The genetic code consists of sequences of nucleotides represented by A, U, C, G.
- It is read in groups of three called codons.
- Each codon specifies a specific amino acid.
Codons
- Codons are groups of three nucleotides.
- Start Codon: AUG (think "August" to remember school starts in August).
- Stop Codons: UAA, UAG, UGA.
- The code is degenerate, meaning multiple codons can specify the same amino acid.
Reading the Genetic Code
- Identify groups of three (codons).
- Use a chart to determine the amino acid for each codon.
- Example: UGG = Tryptophan (Trp); AGC = Serine (Ser);
- Translate a sequence:
- Mark off groups of three.
- Identify the start codon.
- Translate the sequence until reaching a stop codon.
Translation Process
- Start: Begins with the start codon (AUG).
- Coding Sequence: The middle part containing all the codons.
- Stop: Ends at a stop codon.
Importance of Accurate Translation
- Mutation effects: A single nucleotide change can shift reading frames and alter proteins.
mRNA, tRNA, and rRNA
- mRNA: Provides the codon sequence for translation.
- tRNA: Contains an anticodon that is complementary to mRNA codons and carries amino acids.
- rRNA: Forms the ribosome, facilitating the binding of tRNA and mRNA.
Translation Stages
- Initiation: mRNA, tRNA, and ribosome assembly.
- Elongation: Codon-by-codon addition of amino acids.
- Termination: Reaching the stop codon, resulting in a complete polypeptide.
Practical Application: mRNA Vaccines
- Traditional Vaccines: Use weakened/inactivated pathogens or antigens.
- mRNA Vaccines: Use mRNA to instruct cells to produce a viral protein, eliciting an immune response.
- Example: COVID-19 mRNA vaccines instruct cells to make spike proteins, allowing the immune system to recognize and combat the virus.
- Safety: Does not involve the live virus and does not integrate into DNA.
Summary
- Understanding translation is crucial in biotechnology and medicine.
- The process is integral to many applications, including vaccine development.
Make sure to review related materials on translation and bring any questions to the next class.