Biology
Genes of eukaryotic cells containing introns and exons. Introns, short for intervening sequences, are non-coding regions of a gene. They are transcribed but not translated into the amino acid sequence of proteins. Exons, or expressed sequences, are coding regions of a gene and they are transcribed and translated into the amino acid sequence of proteins.
During transcription, both introns and exons are transcribed from the DNA. The primary mRNA transcript therefore contains both introns and exons.
mRNA splicing occurs and special enzymes attach to mRNA strand and the introns are cut out and the two ends of adjacent exons are then connected together. The functional mRNA molecule that is exported from the nucleus is therefore much shorter and this is the RNA that will be translated to a protein molecule.
- Some Dna Sequences Code For More Than One Protein
KEY CONCEPTS:The use of alternative initiation or termination codons allows two proteins to be generated where one is equivalent to a fragment of the other. Nonhomologous protein sequences can be produced from the same sequence of DNA when it is read...
- Genes Show A Wide Distribution Of Sizes
KEY CONCEPTS:Most genes are uninterrupted in yeasts, but are interrupted in higher eukaryotes. Exons are usually short, typically coding for <100 amino acids. Introns are short in lower eukaryotes, but range up to several 10s of kb in length in higher...
- Exon Sequences Are Conserved But Introns Vary
KEY CONCEPTS:Comparisons of related genes in different species show that the sequences of the corresponding exons are usually conserved but the sequences of the introns are much less well related. Introns evolve much more rapidly than exons because of...
- An Interrupted Gene Consists Of Exons And Introns
KEY CONCEPTS:Introns are removed by the process of RNA splicing, which occurs only in cis on an individual RNA molecule. Only mutations in exons can affect protein sequence, but mutations in introns can affect processing of the RNA and therefore prevent...
- Several Processes Are Required To Express The Protein Product Of A Gene
KEY TERMS:Messenger RNA (mRNA) is the intermediate that represents one strand of a gene coding for protein. Its coding region is related to the protein sequence by the triplet genetic code. Transcription describes synthesis of RNA on a DNA template....
Biology
mRNA splicing
Genes of eukaryotic cells containing introns and exons. Introns, short for intervening sequences, are non-coding regions of a gene. They are transcribed but not translated into the amino acid sequence of proteins. Exons, or expressed sequences, are coding regions of a gene and they are transcribed and translated into the amino acid sequence of proteins.
During transcription, both introns and exons are transcribed from the DNA. The primary mRNA transcript therefore contains both introns and exons.
mRNA splicing occurs and special enzymes attach to mRNA strand and the introns are cut out and the two ends of adjacent exons are then connected together. The functional mRNA molecule that is exported from the nucleus is therefore much shorter and this is the RNA that will be translated to a protein molecule.
- Some Dna Sequences Code For More Than One Protein
KEY CONCEPTS:The use of alternative initiation or termination codons allows two proteins to be generated where one is equivalent to a fragment of the other. Nonhomologous protein sequences can be produced from the same sequence of DNA when it is read...
- Genes Show A Wide Distribution Of Sizes
KEY CONCEPTS:Most genes are uninterrupted in yeasts, but are interrupted in higher eukaryotes. Exons are usually short, typically coding for <100 amino acids. Introns are short in lower eukaryotes, but range up to several 10s of kb in length in higher...
- Exon Sequences Are Conserved But Introns Vary
KEY CONCEPTS:Comparisons of related genes in different species show that the sequences of the corresponding exons are usually conserved but the sequences of the introns are much less well related. Introns evolve much more rapidly than exons because of...
- An Interrupted Gene Consists Of Exons And Introns
KEY CONCEPTS:Introns are removed by the process of RNA splicing, which occurs only in cis on an individual RNA molecule. Only mutations in exons can affect protein sequence, but mutations in introns can affect processing of the RNA and therefore prevent...
- Several Processes Are Required To Express The Protein Product Of A Gene
KEY TERMS:Messenger RNA (mRNA) is the intermediate that represents one strand of a gene coding for protein. Its coding region is related to the protein sequence by the triplet genetic code. Transcription describes synthesis of RNA on a DNA template....