unit 4 - transcription, translation, and mutations

anticodon

three-nucleotide sequence in a tRNA molecule that corresponds to an mRNA codon

central dogma

states that genes specify the sequence of mRNAs, which in turn specify the sequence of proteins

codon

three consecutive nucleotides in mRNA that specify the insertion of an amino acid or the release of a polypeptide chain during translation triplet; the code is degenerate, but not ambiguous complex that “facilitates chromatin transcription” by disassembling nucleosomes ahead of a transcribing RNA polymerase II and reassembling them after the polymerase passes by

intron

non–protein-coding intervening sequences that are spliced from mRNA during processing

nontemplate strand

strand of DNA that is not used to transcribe mRNA; this strand is identical to the mRNA except that T nucleotides in the DNA are replaced by U nucleotides in the mRNA

poly-A tail

modification added to the 3' end of pre-mRNAs to protect mRNA from degradation and assist mRNA export from the nucleus

promoter

DNA sequence to which RNA polymerase and associated factors bind and initiate transcription

splicing

process of removing introns and reconnecting exons in a pre

start codon

AUG (or rarely, GUG) on an mRNA from which translation begins; always specifies methionine

TATA box

conserved promoter sequence in eukaryotes and prokaryotes that helps to establish the initiation site for transcription

template strand

strand of DNA that specifies the complementary mRNA molecule

3' UTR

3' untranslated region; region just downstream of the protein

5' cap

a methylated guanosine triphosphate (GTP) molecule that is attached to the 5' end of a messenger RNA to protect the end from degradation

5' UTR

5' untranslated region

transcription factor

protein that binds to the DNA at the promoter or enhancer region and that influences transcription of a gene

untranslated region

segment of the RNA molecule that is not translated into protein. These regions lie before (upstream or 5') and after (downstream or 3') the protein-coding region