Translation is the process by which a ribosome reads an mRNA message and builds a polypeptide. This lesson introduces the genetic code and the molecular components that make translation possible.
A protein is built from amino acids, while an mRNA message is written in nucleotides. Translation connects these two information systems. Each group of three nucleotides in mRNA is a codon, and each codon either specifies an amino acid or signals the end of translation.
All flashcards
What is a codon?
A codon is a sequence of three nucleotides in mRNA that specifies an amino acid or signals translation to stop.
What are degeneracy and wobble?
Degeneracy means that multiple codons can specify the same amino acid. Wobble refers to the reduced specificity often tolerated at the third codon position.
What is the function of the AUG codon?
AUG specifies methionine and usually acts as the start codon, establishing the reading frame for translation.
What does a tRNA anticodon do?
The anticodon is a three-nucleotide sequence that pairs with a complementary mRNA codon, helping deliver the corresponding amino acid.
What does an aminoacyl-tRNA synthetase do?
It recognizes a particular amino acid and its cognate tRNA, then attaches the amino acid to the tRNA to produce a charged tRNA.
Quiz questions
What normally happens when a stop codon reaches the ribosome's A site?Answer: A release factor recognizes the signal and promotes polypeptide release.
In which direction does a ribosome read an mRNA during translation?Answer: From 5′ to 3′.
What occurs during ribosomal translocation?Answer: The ribosome advances one codon as tRNAs shift between binding sites.
How does a eukaryotic ribosome typically locate the start codon during initiation?Answer: The small-subunit complex recognizes the 5′ cap and scans toward an AUG.
What is the primary role of the ribosomal A site during elongation?Answer: It accepts an incoming charged tRNA matching the next codon.
Based on Microbiology by Nina Parker, Mark Schneegurt, Anh-Hue Thi Tu, Philip Lister, Brian M. Forster (OpenStax), licensed CC BY 4.0. Adapted into a summary, flashcards and quizzes.