Biochemistry - Ch 26 - Rna Metabolism (Vocab)

Front 1

Define:

Ribosomal RNA

Back 1

(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.

Front 2

Define:

Transfer RNA

Back 2

(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.

Front 3

Define:

Messenger RNA

Back 3

(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.

Front 4

Define:

RNAp

Back 4

RNA polymerase, the enzyme that synthesizes RNA using a DNA template.

Front 5

Define:

Holoenzyme

Back 5

A catalytically active enzyme-cofactor complex.

Front 6

Define:

σ factor

Back 6

(Sigma factor)

A prokaryotic helicase that separates DNA and RNA to promote transcription termination.

Front 7

Define:

Antisense strand

Back 7

*Also called the non-coding strand*

The DNA strand that serves as a template for transcription; it is complementary to the RNA.

Front 8

Define:

Non-coding strand

Back 8

*Also called the Antisense strand*

The DNA strand that serves as a template for transcription; it is complementary to the RNA.

Front 9

Define:

Sense strand

Back 9

*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.

Front 10

Define:

Coding strand

Back 10

*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.

Front 11

Define:

Structural gene

Back 11

A gene that encodes a protein.

Front 12

Define:

Operon

Back 12

A prokaryotic genetic unit that consists of several genes with related functions that are transcribed as a single mRNA molecule.

Front 13

Define:

Cistron

Back 13

An archaic term for a gene

Front 14

Define:

Promoter

Back 14

One of two or more identical units of an oligomeric protein. A promoter may consist of one or more polypeptide chains.

Front 15

Define:

Pribnow box

Back 15

The prokaryotic promoter element with the consensus sequence TATAAT that is centered at around the -10 position relative to the transcription start site

Front 16

Define:

Rho factor

Back 16

A prokaryotic helicase that separates DNA and RNA to promote transcription termination.

Front 17

Define:

Nucleolus

Back 17

(pl. nucleoli)

The dark-staining region of the eukaryotic nucleus, where ribosomes are assembled.

Front 18

Define:

Primary transcript

Back 18

The immediate product of transcription, which may be modified before becoming fully functional.

Front 19

Define:

Posttransctiptional modification

Back 19

The removal or addition of nucleotide residues or their modification following the synthesis of RNA.

Front 20

Define:

Cap

Back 20

A 7-methylguanosine residue that is posttranctiptionally appended to the 5' end of a eukaryotic mRNA.

Front 21

Define:

Poly(A) tail

Back 21

The sequence of adenylate residues that is posttranscriptionally appended to the 3' end of eukaryotic mRNAs.

Front 22

Define:

Heterogenous nuclear RNA

Back 22

(hnRNA)

Eukaryotic mRNA primary transcripts whose introns have not yet been excised.

Front 23

Define:

Intron

Back 23

A portion of a gene that is transcribed but excised prior to translation. Also called an intervening sequence.

Front 24

Define:

Exon

Back 24

A portion of a gene that appears in both the primary and mature mRNA transcripts.

Also called an expressed sequence.

Front 25

Define:

Splicing

Back 25

the usually ribonucleoprotein-catalyzed process by which introns are removed and exons are joined to produce a mature transcript.

Some RNAs are self-splicing.