Chapter 14.txt

Event by which the same gene can specify two or more slightly different proteins. All exons in a pre-mRNA transcript of the gene are retained or some are removed and the rest spliced in various combinations for the mature transcript.

A small organic compound with a carboxylic acid group, an amino group, and a characteristic side group (R); monomer of polypeptide chains.

Series of three nucleotide bases in tRNA that can base-pair with mRNA codons.

Linear order of nucleotides that compose a DNA or RNA strand.

Mutation in which one nucleotide is wrongly substituted for another during DNA replication.

Loss of a chromosome segment; often leads to genetic disorders. Also the loss of one or more nucleotide bases from a DNA molecule.

A base sequence in eukaryotic DNA that is part or all of a protein-encoding gene; may or may not be excised from a pre-mRNA during transcript processing.

Small-scale change in the nucleotide sequence of a gene; can result in an altered protein product.

Correspondence between triplets of nucleotides in DNA and mRNA, and specific sequences of amino acids in a polypeptide chain; near-universal language of protein synthesis; mitochondria and a few species have a few variant code words.

A mutation by which one or more bases are introduced into a DNA strand. Also a movable attachment of muscle to bone.

One of the noncoding sequences in eukaryotic genes; it is excised from the pre-mRNA transcripts before translation.

Form of radiation with enough energy to eject electrons from atoms.

mRNA. A single strand of ribonucleotides transcribed from DNA; the only type of RNA that carries proteinbuilding information to ribosomes.

Of a given gene locus, the probability that a spontaneous mutation will happen in a specified interval.

Form of radiation that carries enough energy to boost electrons to higher energy levels but not enough to eject them from an atom.

A series of ribosomes that are all translating the same mRNA molecule at the same time.

Short stretch of DNA to which RNA polymerase binds. Transcription then begins at the gene closest to the promoter.

rRNA. A class of RNA that becomes complexed with proteins to form ribosomes; some catalyze assembly of polypeptide chains.

The site of polypeptide chain synthesis in all cells. An intact ribosome has two subunits of rRNA and proteins.

Enzyme that catalyzes transcription of DNA into RNA.

[L. trans, across, + scribere, to write] First stage of protein synthesis. An RNA strand is assembled from nucleotides using a gene region in DNA as a template.

tRNA. One of a class of small RNA molecules that delivers amino acids to a ribosome. Its anticodon pairs with an mRNA codon during translation.

Second stage of protein synthesis. At ribosomes, information encoded in an mRNA transcript guides the synthesis of a new polypeptide chain from amino acids.

Transposable element. A stretch of DNA that jumps spontaneously and randomly to a different location in the genome and may mutate a gene.

One of four nitrogencontaining bases in nucleotide monomers of RNA; also applies to a nucleotide with a uracil base component. Like thymine, uracil can base-pair with adenine.