{"id":1002,"date":"2022-04-20T21:05:35","date_gmt":"2022-04-20T21:05:35","guid":{"rendered":"https:\/\/pressbooks.hcfl.edu\/bio1\/chapter\/key-terms-15\/"},"modified":"2025-08-29T19:16:23","modified_gmt":"2025-08-29T19:16:23","slug":"key-terms-15","status":"publish","type":"chapter","link":"https:\/\/pressbooks.hcfl.edu\/bio1\/chapter\/key-terms-15\/","title":{"raw":"Key Terms","rendered":"Key Terms"},"content":{"raw":"
\n \t
\n
\n \t
7-methylguanosine cap<\/dt>\n \t
modification added to the 5' end of pre-mRNAs to protect mRNA from degradation and assist translation<\/dd>\n<\/dl>\n
\n \t
aminoacyl tRNA synthetase<\/dt>\n \t
enzyme that \u201ccharges\u201d tRNA molecules by catalyzing a bond between the tRNA and a corresponding amino acid<\/dd>\n<\/dl>\n
\n \t
anticodon<\/dt>\n \t
three-nucleotide sequence in a tRNA molecule that corresponds to an mRNA codon<\/dd>\n<\/dl>\n
\n \t
CAAT box<\/dt>\n \t
(GGCCAATCT) essential eukaryotic promoter sequence involved in binding transcription factors<\/dd>\n<\/dl>\n
\n \t
central dogma<\/dt>\n \t
states that genes specify the sequence of mRNAs, which in turn specify the sequence of proteins<\/dd>\n<\/dl>\n
\n \t
codon<\/dt>\n \t
three consecutive nucleotides in mRNA that specify the insertion of an amino acid or the release of a polypeptide chain during translation<\/dd>\n<\/dl>\n
\n \t
colinear<\/dt>\n \t
in terms of RNA and protein, three \u201cunits\u201d of RNA (nucleotides) specify one \u201cunit\u201d of protein (amino acid) in a consecutive fashion<\/dd>\n<\/dl>\n
\n \t
consensus<\/dt>\n \t
DNA sequence that is used by many species to perform the same or similar functions<\/dd>\n<\/dl>\n
\n \t
core enzyme<\/dt>\n \t
prokaryotic RNA polymerase consisting of\u00a0\u03b1<\/em>,\u00a0\u03b1<\/em>,\u00a0\u03b2<\/em>, and\u00a0\u03b2<\/em>' but missing\u00a0\u03c3<\/em>; this complex performs elongation<\/dd>\n<\/dl>\n
\n \t
degeneracy<\/dt>\n \t
(of the genetic code) describes that a given amino acid can be encoded by more than one nucleotide triplet; the code is degenerate, but not ambiguous<\/dd>\n<\/dl>\n
\n \t
downstream<\/dt>\n \t
nucleotides following the initiation site in the direction of mRNA transcription; in general, sequences that are toward the 3' end relative to a site on the mRNA<\/dd>\n<\/dl>\n
\n \t
exon<\/dt>\n \t
sequence present in protein-coding mRNA after completion of pre-mRNA splicing<\/dd>\n<\/dl>\n
\n \t
FACT<\/dt>\n \t
complex that \u201cfacilitates chromatin transcription\u201d by disassembling nucleosomes ahead of a transcribing RNA polymerase II and reassembling them after the polymerase passes by<\/dd>\n<\/dl>\n
\n \t
GC-rich box<\/dt>\n \t
(GGCG) nonessential eukaryotic promoter sequence that binds cellular factors to increase the efficiency of transcription; may be present several times in a promoter<\/dd>\n<\/dl>\n
\n \t
hairpin<\/dt>\n \t
structure of RNA when it folds back on itself and forms intramolecular hydrogen bonds between complementary nucleotides<\/dd>\n<\/dl>\n
\n \t
holoenzyme<\/dt>\n \t
prokaryotic RNA polymerase consisting of\u00a0\u03b1<\/em>,\u00a0\u03b1<\/em>,\u00a0\u03b2<\/em>,\u00a0\u03b2<\/em>', and\u00a0\u03c3<\/em>; this complex is responsible for transcription initiation<\/dd>\n<\/dl>\n
\n \t
initiation site<\/dt>\n \t
nucleotide from which mRNA synthesis proceeds in the 5' to 3' direction; denoted with a \u201c+1\u201d<\/dd>\n<\/dl>\n
\n \t
initiator tRNA<\/dt>\n \t
in prokaryotes, called\u00a0<\/span>[latex]tRNA \\frac{Met}{f}[\/latex] and <\/span>in eukaryotes, called tRNA<\/span>i<\/sub>; a tRNA that interacts with a start codon, binds directly to the ribosome P site, and links to a special methionine to begin a polypeptide chain<\/span><\/span><\/dt>\n<\/dl>\n
\n \t
intron<\/dt>\n \t
non\u2013protein-coding intervening sequences that are spliced from mRNA during processing<\/dd>\n<\/dl>\n
\n \t
Kozak\u2019s rules<\/dt>\n \t
determines the correct initiation AUG in a eukaryotic mRNA; the following consensus sequence must appear around the AUG: 5\u2019-GCC(purine<\/strong>)CCAUG<\/u>G<\/strong>-3\u2019; the bolded bases are most important<\/dd>\n<\/dl>\n
\n \t
nonsense codon<\/dt>\n \t
one of the three mRNA codons that specifies termination of translation<\/dd>\n<\/dl>\n
\n \t
nontemplate strand<\/dt>\n \t
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<\/dd>\n<\/dl>\n
\n \t
Octamer box<\/dt>\n \t
(ATTTGCAT) nonessential eukaryotic promoter sequence that binds cellular factors to increase the efficiency of transcription; may be present several times in a promoter<\/dd>\n<\/dl>\n
\n \t
peptidyl transferase<\/dt>\n \t
RNA-based enzyme that is integrated into the 50S ribosomal subunit and catalyzes the formation of peptide bonds<\/dd>\n<\/dl>\n
\n \t
plasmid<\/dt>\n \t
extrachromosomal, covalently closed, circular DNA molecule that may only contain one or a few genes; common in prokaryotes<\/dd>\n<\/dl>\n
\n \t
poly-A tail<\/dt>\n \t
modification added to the 3' end of pre-mRNAs to protect mRNA from degradation and assist mRNA export from the nucleus<\/dd>\n<\/dl>\n
\n \t
polysome<\/dt>\n \t
mRNA molecule simultaneously being translated by many ribosomes all going in the same direction<\/dd>\n<\/dl>\n
\n \t
preinitiation complex<\/dt>\n \t
cluster of transcription factors and other proteins that recruit RNA polymerase II for transcription of a DNA template<\/dd>\n<\/dl>\n
\n \t
promoter<\/dt>\n \t
DNA sequence to which RNA polymerase and associated factors bind and initiate transcription<\/dd>\n<\/dl>\n
\n \t
reading frame<\/dt>\n \t
sequence of triplet codons in mRNA that specify a particular protein; a ribosome shift of one or two nucleotides in either direction completely abolishes synthesis of that protein<\/dd>\n<\/dl>\n
\n \t
rho-dependent termination<\/dt>\n \t
in prokaryotes, termination of transcription by an interaction between RNA polymerase and the rho protein at a run of G nucleotides on the DNA template<\/dd>\n<\/dl>\n
\n \t
rho-independent<\/dt>\n \t
termination sequence-dependent termination of prokaryotic mRNA synthesis; caused by hairpin formation in the mRNA that stalls the polymerase<\/dd>\n<\/dl>\n
\n \t
RNA editing<\/dt>\n \t
direct alteration of one or more nucleotides in an mRNA that has already been synthesized<\/dd>\n<\/dl>\n
\n \t
Shine-Dalgarno sequence<\/dt>\n \t
(AGGAGG); initiates prokaryotic translation by interacting with rRNA molecules comprising the 30S ribosome<\/dd>\n<\/dl>\n
\n \t
signal sequence<\/dt>\n \t
short tail of amino acids that directs a protein to a specific cellular compartment<\/dd>\n<\/dl>\n
\n \t
small nuclear RNA<\/dt>\n \t
molecules synthesized by RNA polymerase III that have a variety of functions, including splicing pre-mRNAs and regulating transcription factors<\/dd>\n<\/dl>\n
\n \t
splicing<\/dt>\n \t
process of removing introns and reconnecting exons in a pre-mRNA<\/dd>\n<\/dl>\n
\n \t
start codon<\/dt>\n \t
AUG (or rarely, GUG) on an mRNA from which translation begins; always specifies methionine<\/dd>\n<\/dl>\n
\n \t
TATA box<\/dt>\n \t
conserved promoter sequence in eukaryotes and prokaryotes that helps to establish the initiation site for transcription<\/dd>\n<\/dl>\n
\n \t
template strand<\/dt>\n \t
strand of DNA that specifies the complementary mRNA molecule<\/dd>\n<\/dl>\n
\n \t
transcription bubble<\/dt>\n \t
region of locally unwound DNA that allows for transcription of mRNA<\/dd>\n<\/dl>\n
\n \t
upstream<\/dt>\n \t
nucleotides preceding the initiation site; in general, sequences toward the 5' end relative to a site on the mRNA<\/dd>\n<\/dl>\n<\/dt>\n<\/dl>","rendered":"
\n
\n<\/dt>\n
7-methylguanosine cap<\/dt>\n
modification added to the 5′ end of pre-mRNAs to protect mRNA from degradation and assist translation<\/dd>\n<\/dl>\n
\n
aminoacyl tRNA synthetase<\/dt>\n
enzyme that \u201ccharges\u201d tRNA molecules by catalyzing a bond between the tRNA and a corresponding amino acid<\/dd>\n<\/dl>\n
\n
anticodon<\/dt>\n
three-nucleotide sequence in a tRNA molecule that corresponds to an mRNA codon<\/dd>\n<\/dl>\n
\n
CAAT box<\/dt>\n
(GGCCAATCT) essential eukaryotic promoter sequence involved in binding transcription factors<\/dd>\n<\/dl>\n
\n
central dogma<\/dt>\n
states that genes specify the sequence of mRNAs, which in turn specify the sequence of proteins<\/dd>\n<\/dl>\n
\n
codon<\/dt>\n
three consecutive nucleotides in mRNA that specify the insertion of an amino acid or the release of a polypeptide chain during translation<\/dd>\n<\/dl>\n
\n
colinear<\/dt>\n
in terms of RNA and protein, three \u201cunits\u201d of RNA (nucleotides) specify one \u201cunit\u201d of protein (amino acid) in a consecutive fashion<\/dd>\n<\/dl>\n
\n
consensus<\/dt>\n
DNA sequence that is used by many species to perform the same or similar functions<\/dd>\n<\/dl>\n
\n
core enzyme<\/dt>\n
prokaryotic RNA polymerase consisting of\u00a0\u03b1<\/em>,\u00a0\u03b1<\/em>,\u00a0\u03b2<\/em>, and\u00a0\u03b2<\/em>‘ but missing\u00a0\u03c3<\/em>; this complex performs elongation<\/dd>\n<\/dl>\n
\n
degeneracy<\/dt>\n
(of the genetic code) describes that a given amino acid can be encoded by more than one nucleotide triplet; the code is degenerate, but not ambiguous<\/dd>\n<\/dl>\n
\n
downstream<\/dt>\n
nucleotides following the initiation site in the direction of mRNA transcription; in general, sequences that are toward the 3′ end relative to a site on the mRNA<\/dd>\n<\/dl>\n
\n
exon<\/dt>\n
sequence present in protein-coding mRNA after completion of pre-mRNA splicing<\/dd>\n<\/dl>\n
\n
FACT<\/dt>\n
complex that \u201cfacilitates chromatin transcription\u201d by disassembling nucleosomes ahead of a transcribing RNA polymerase II and reassembling them after the polymerase passes by<\/dd>\n<\/dl>\n
\n
GC-rich box<\/dt>\n
(GGCG) nonessential eukaryotic promoter sequence that binds cellular factors to increase the efficiency of transcription; may be present several times in a promoter<\/dd>\n<\/dl>\n
\n
hairpin<\/dt>\n
structure of RNA when it folds back on itself and forms intramolecular hydrogen bonds between complementary nucleotides<\/dd>\n<\/dl>\n
\n
holoenzyme<\/dt>\n
prokaryotic RNA polymerase consisting of\u00a0\u03b1<\/em>,\u00a0\u03b1<\/em>,\u00a0\u03b2<\/em>,\u00a0\u03b2<\/em>‘, and\u00a0\u03c3<\/em>; this complex is responsible for transcription initiation<\/dd>\n<\/dl>\n
\n
initiation site<\/dt>\n
nucleotide from which mRNA synthesis proceeds in the 5′ to 3′ direction; denoted with a \u201c+1\u201d<\/dd>\n<\/dl>\n
\n
initiator tRNA<\/dt>\n
in prokaryotes, called\u00a0<\/span>[latex]tRNA \\frac{Met}{f}[\/latex] and <\/span>in eukaryotes, called tRNA<\/span>i<\/sub>; a tRNA that interacts with a start codon, binds directly to the ribosome P site, and links to a special methionine to begin a polypeptide chain<\/span><\/span><\/dt>\n<\/dl>\n
\n
intron<\/dt>\n
non\u2013protein-coding intervening sequences that are spliced from mRNA during processing<\/dd>\n<\/dl>\n
\n
Kozak\u2019s rules<\/dt>\n
determines the correct initiation AUG in a eukaryotic mRNA; the following consensus sequence must appear around the AUG: 5\u2019-GCC(purine<\/strong>)CCAUG<\/u>G<\/strong>-3\u2019; the bolded bases are most important<\/dd>\n<\/dl>\n
\n
nonsense codon<\/dt>\n
one of the three mRNA codons that specifies termination of translation<\/dd>\n<\/dl>\n
\n
nontemplate strand<\/dt>\n
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<\/dd>\n<\/dl>\n
\n
Octamer box<\/dt>\n
(ATTTGCAT) nonessential eukaryotic promoter sequence that binds cellular factors to increase the efficiency of transcription; may be present several times in a promoter<\/dd>\n<\/dl>\n
\n
peptidyl transferase<\/dt>\n
RNA-based enzyme that is integrated into the 50S ribosomal subunit and catalyzes the formation of peptide bonds<\/dd>\n<\/dl>\n
\n
plasmid<\/dt>\n
extrachromosomal, covalently closed, circular DNA molecule that may only contain one or a few genes; common in prokaryotes<\/dd>\n<\/dl>\n
\n
poly-A tail<\/dt>\n
modification added to the 3′ end of pre-mRNAs to protect mRNA from degradation and assist mRNA export from the nucleus<\/dd>\n<\/dl>\n
\n
polysome<\/dt>\n
mRNA molecule simultaneously being translated by many ribosomes all going in the same direction<\/dd>\n<\/dl>\n
\n
preinitiation complex<\/dt>\n
cluster of transcription factors and other proteins that recruit RNA polymerase II for transcription of a DNA template<\/dd>\n<\/dl>\n
\n
promoter<\/dt>\n
DNA sequence to which RNA polymerase and associated factors bind and initiate transcription<\/dd>\n<\/dl>\n
\n
reading frame<\/dt>\n
sequence of triplet codons in mRNA that specify a particular protein; a ribosome shift of one or two nucleotides in either direction completely abolishes synthesis of that protein<\/dd>\n<\/dl>\n
\n
rho-dependent termination<\/dt>\n
in prokaryotes, termination of transcription by an interaction between RNA polymerase and the rho protein at a run of G nucleotides on the DNA template<\/dd>\n<\/dl>\n
\n
rho-independent<\/dt>\n
termination sequence-dependent termination of prokaryotic mRNA synthesis; caused by hairpin formation in the mRNA that stalls the polymerase<\/dd>\n<\/dl>\n
\n
RNA editing<\/dt>\n
direct alteration of one or more nucleotides in an mRNA that has already been synthesized<\/dd>\n<\/dl>\n
\n
Shine-Dalgarno sequence<\/dt>\n
(AGGAGG); initiates prokaryotic translation by interacting with rRNA molecules comprising the 30S ribosome<\/dd>\n<\/dl>\n
\n
signal sequence<\/dt>\n
short tail of amino acids that directs a protein to a specific cellular compartment<\/dd>\n<\/dl>\n
\n
small nuclear RNA<\/dt>\n
molecules synthesized by RNA polymerase III that have a variety of functions, including splicing pre-mRNAs and regulating transcription factors<\/dd>\n<\/dl>\n
\n
splicing<\/dt>\n
process of removing introns and reconnecting exons in a pre-mRNA<\/dd>\n<\/dl>\n
\n
start codon<\/dt>\n
AUG (or rarely, GUG) on an mRNA from which translation begins; always specifies methionine<\/dd>\n<\/dl>\n
\n
TATA box<\/dt>\n
conserved promoter sequence in eukaryotes and prokaryotes that helps to establish the initiation site for transcription<\/dd>\n<\/dl>\n
\n
template strand<\/dt>\n
strand of DNA that specifies the complementary mRNA molecule<\/dd>\n<\/dl>\n
\n
transcription bubble<\/dt>\n
region of locally unwound DNA that allows for transcription of mRNA<\/dd>\n<\/dl>\n
\n
upstream<\/dt>\n
nucleotides preceding the initiation site; in general, sequences toward the 5′ end relative to a site on the mRNA<\/dd>\n<\/dl>\n","protected":false},"author":130,"menu_order":7,"template":"","meta":{"pb_show_title":"on","pb_short_title":"","pb_subtitle":"","pb_authors":["jung-choi","mary-ann-clark","matthew-douglas"],"pb_section_license":"cc-by"},"chapter-type":[],"contributor":[92,93,94],"license":[53],"class_list":["post-1002","chapter","type-chapter","status-publish","hentry","contributor-jung-choi","contributor-mary-ann-clark","contributor-matthew-douglas","license-cc-by"],"part":974,"_links":{"self":[{"href":"https:\/\/pressbooks.hcfl.edu\/bio1\/wp-json\/pressbooks\/v2\/chapters\/1002","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/pressbooks.hcfl.edu\/bio1\/wp-json\/pressbooks\/v2\/chapters"}],"about":[{"href":"https:\/\/pressbooks.hcfl.edu\/bio1\/wp-json\/wp\/v2\/types\/chapter"}],"author":[{"embeddable":true,"href":"https:\/\/pressbooks.hcfl.edu\/bio1\/wp-json\/wp\/v2\/users\/130"}],"version-history":[{"count":1,"href":"https:\/\/pressbooks.hcfl.edu\/bio1\/wp-json\/pressbooks\/v2\/chapters\/1002\/revisions"}],"predecessor-version":[{"id":1003,"href":"https:\/\/pressbooks.hcfl.edu\/bio1\/wp-json\/pressbooks\/v2\/chapters\/1002\/revisions\/1003"}],"part":[{"href":"https:\/\/pressbooks.hcfl.edu\/bio1\/wp-json\/pressbooks\/v2\/parts\/974"}],"metadata":[{"href":"https:\/\/pressbooks.hcfl.edu\/bio1\/wp-json\/pressbooks\/v2\/chapters\/1002\/metadata\/"}],"wp:attachment":[{"href":"https:\/\/pressbooks.hcfl.edu\/bio1\/wp-json\/wp\/v2\/media?parent=1002"}],"wp:term":[{"taxonomy":"chapter-type","embeddable":true,"href":"https:\/\/pressbooks.hcfl.edu\/bio1\/wp-json\/pressbooks\/v2\/chapter-type?post=1002"},{"taxonomy":"contributor","embeddable":true,"href":"https:\/\/pressbooks.hcfl.edu\/bio1\/wp-json\/wp\/v2\/contributor?post=1002"},{"taxonomy":"license","embeddable":true,"href":"https:\/\/pressbooks.hcfl.edu\/bio1\/wp-json\/wp\/v2\/license?post=1002"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}