in messenger rna each codon specifies a particular

IN MESSENGER RNA EACH CODON SPECIFIES A PARTICULAR CODE

The genetic code is the information for linking amino acids into polypeptides in an order based on the base sequence of 3-base codewords (codons) in a gene and its messenger RNA (mRNA).įor example, the amino acid tryptophan is encoded by the sequence UGG on an mRNA. The sequence of an mRNA, copied from a gene, directly specifies the sequence of amino acids in the protein it encodes. Genes are first transcribed into mRNA, as we have already discussed. How does this relate to genes and the proteins they encode? Also, luggage handlers must be able to correctly recognize what IND stands for so that your luggage doesn’t land in Iowa, instead. That is, IND must stand only for Indianapolis, Indiana and no other airport. To function well, such a set-up must have unique identifiers for each airport and people who can decode the identifiers correctly. When a tag on your luggage shows IND as the destination, it conveys information that your bag should be sent to Indianapolis, Indiana.

IN MESSENGER RNA EACH CODON SPECIFIES A PARTICULAR CODE

What does this actually mean? A code can be thought of as a system for storing or communicating information.Īnalogy: A familiar example is the use of letters to represent the names of airports (e.g., PDX for Portland, Oregon and ORD for Chicago’s O’Hare).

We speak of genes (i.e., DNA) coding for proteins and the central dogma, which states that DNA makes RNA makes protein.

Be familiar with the genetic code and be able to use it to deduce the primary structure of a polypeptide from an mRNA sequence.

What is the wobble hypothesis and how does it fit with the fact that the genetic code is degenerate?.Define the following terms as they apply to the genetic code: Reading frame, Initiation codon, Termination codon, Sense Codon.Explain what the terms nonoverlapping, commaless (without punctuation), degenerate, and unambiguous mean with respect to the genetic code.It requires a mature mRNA to serve as the template, and performs peptide bond synthesis in a directional fashion from the N to the C-terminal of the growing peptide/protein. The ribosome (a large complex of peptides and rRNA molecules) serves as the enzyme that mediates this reaction. Recall that peptide formation is a dehydration reaction that combines the carboxylic acid of the upstream amino acid with the amine functional group of the downstream amino acid to form an amide linkage (Fig. (a) Prokaryotes lack cellular compartmentalization and show coupled transcription-translation processing, whereas (b) eukaryotes have a high degree of compartmentalization and separate the processes of transcription, which is in the nucleus of the cell, from the processes of translation, which is localized in the cytoplasm.Figure from: Baccei, A., and Rice, M. 10.1 A).įigure 10.1 Cellular Location of Transcription and Translation in Prokayotes and Eukaryotes. Prokaryotes do not have compartmentalization and have, thus, evolved a coupled transcription/translation system where both process occur simultaneously (Fig. Transcription occurs within the nucleus of eukaryotes and translation occurs within the cytoplasm (Fig. Due to this compartmentalization, transcription and translation are separated spatially and temporally within the cell. Recall that prokaryotic and eukaryotic transcription and translation systems differ in large part due to the compartmentalization of larger eukaryotic cells. The sequential polymerization of amino acids, in a strict order determined by the sequence of an mRNA, is catalyzed by a ribonucleoprotein complex called the ribosome working with decoding “keys” termed charged tRNAs. Essentially, you are translating the language of nucleotides into the language of amino acids.Īmino acids are linearly strung together via covalent bonds (called peptide bonds) between amino and carboxyl termini of adjacent amino acids. Translation is the process of converting the information housed in mRNA into the protein sequence. Within this chapter, we will cover the details of prokaryotic and eukaryotic translation. Molecular Biology: From DNA to RNA to Protein 10 Genetic Code and Translation 10.1 Overview of Translation

In messenger rna each codon specifies a particular