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25 Cards in this Set
- Front
- Back
Define:
Ribosomal RNA |
(rRNA)
The RNA molecules that constitute the bulk of the ribosome, the site of polypeptide synthesis. rRNA provides structural scaffolding for the ribosome and catalyzes peptide bond formation. |
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Define:
Transfer RNA |
(tRNA)
The small L-shaped RNAs that deliver specific amino acids, which have been esterified to the tRNA's 3' ends, to ribosomes according to the sequence of a bound mRNA. The proper tRNA is selected through the complementary base pairing of its three-nucleotide anticodon with the mRNA's codon, and the growing polypeptide is transferred to its aminoacyl group. |
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Define:
Messenger RNA |
(mRNA)
A ribonucleic acid whose sequence is complementary to that of a protein-coding gene in DNA. In the ribosome, mRNA directs the polymerization of amino acids to form a polypeptide with the corresponding sequence. |
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Define:
RNAp |
RNA polymerase, the enzyme that synthesizes RNA using a DNA template.
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Define:
Holoenzyme |
A catalytically active enzyme-cofactor complex.
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Define:
σ factor |
(Sigma factor)
A prokaryotic helicase that separates DNA and RNA to promote transcription termination. |
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Define:
Antisense strand |
*Also called the non-coding strand*
The DNA strand that serves as a template for transcription; it is complementary to the RNA. |
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Define:
Non-coding strand |
*Also called the Antisense strand*
The DNA strand that serves as a template for transcription; it is complementary to the RNA. |
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Define:
Sense strand |
*Also called the coding strand*
The DNA strand complementary to the strand that is transcribed; it has the same base sequence (except for the replacement of U with R) as the synthesized RNA. |
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Define:
Coding strand |
*Also called the sense strand*
The DNA strand complementary to the strand that is transcribed; it has the same base sequence (except for the replacement of U with R) as the synthesized RNA. |
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Define:
Structural gene |
A gene that encodes a protein.
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Define:
Operon |
A prokaryotic genetic unit that consists of several genes with related functions that are transcribed as a single mRNA molecule.
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Define:
Cistron |
An archaic term for a gene
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Define:
Promoter |
One of two or more identical units of an oligomeric protein. A promoter may consist of one or more polypeptide chains.
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Define:
Pribnow box |
The prokaryotic promoter element with the consensus sequence TATAAT that is centered at around the -10 position relative to the transcription start site
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Define:
Rho factor |
A prokaryotic helicase that separates DNA and RNA to promote transcription termination.
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Define:
Nucleolus |
(pl. nucleoli)
The dark-staining region of the eukaryotic nucleus, where ribosomes are assembled. |
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Define:
Primary transcript |
The immediate product of transcription, which may be modified before becoming fully functional.
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Define:
Posttransctiptional modification |
The removal or addition of nucleotide residues or their modification following the synthesis of RNA.
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Define:
Cap |
A 7-methylguanosine residue that is posttranctiptionally appended to the 5' end of a eukaryotic mRNA.
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Define:
Poly(A) tail |
The sequence of adenylate residues that is posttranscriptionally appended to the 3' end of eukaryotic mRNAs.
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Define:
Heterogenous nuclear RNA |
(hnRNA)
Eukaryotic mRNA primary transcripts whose introns have not yet been excised. |
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Define:
Intron |
A portion of a gene that is transcribed but excised prior to translation. Also called an intervening sequence.
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Define:
Exon |
A portion of a gene that appears in both the primary and mature mRNA transcripts.
Also called an expressed sequence. |
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Define:
Splicing |
the usually ribonucleoprotein-catalyzed process by which introns are removed and exons are joined to produce a mature transcript.
Some RNAs are self-splicing. |