Chapter 7 Flashcards
alternative splicing
The production of different mRNAs (and proteins) from the
same gene by splicing its RNA transcripts in different ways.
aminoacyl-tRNA synthetase
During protein synthesis, an enzyme that attaches the
correct amino acid to a tRNA molecule to form a “charged”
aminoacyl-tRNA.
anticodon
Set of three consecutive nucleotides in a transfer RNA
molecule that recognizes, through base-pairing, the threenucleotide codon on a messenger RNA molecule; this
interaction helps to deliver the correct amino acid to a
growing polypeptide chain.
codon
Group of three consecutive nucleotides that specifies
a particular amino acid or that starts or stops protein
synthesis; applies to the nucleotides in an mRNA or in a
coding sequence of DNA.
exon
Segment of a eukaryotic gene that is transcribed into RNA
and dictates the amino acid sequence of part of a protein.
gene
Unit of heredity containing the instructions that dictate the
characteristics or phenotype of an organism; in molecular
terms, a segment of DNA that directs the production of a
particular protein or functional RNA molecule.
gene expression
The process by which a gene makes a product that is useful
to the cell or organism by directing the synthesis of a protein
or an RNA molecule with a characteristic activity.
general transcription factors
Proteins that assemble on the promoters of eukaryotic
genes near the start site of transcription and load the RNA
polymerase in the correct position.
genetic code
Set of rules by which the information contained in the
nucleotide sequence of a gene and its corresponding RNA
G:8 Glossary
molecule is translated into the amino acid sequence of a
protein.
initiator tRNA
Special tRNA that initiates the translation of an mRNA in a
ribosome. It always carries the amino acid methionine.
intron
Noncoding sequence within a eukaryotic gene that is
transcribed into an RNA molecule but is then excised by
RNA splicing to produce an mRNA.
messenger RNA (mRNA)
RNA molecule that specifies the amino acid sequence of a
protein.
polyadenylation
The addition of multiple adenine nucleotide
promoter
DNA sequence that initiates gene transcription; includes
sequences recognized by RNA polymerase and its accessory
proteins.
protease
Enzyme that degrades proteins by hydrolyzing their peptide
bonds.
proteasome
Large protein machine that degrades
proteins that are damaged, misfolded, or no
longer needed by the cell; its target proteins
are marked for destruction primarily by the
attachment of a short chain of ubiquitin.
reading frame
One of the three possible ways in which a set of successive
nucleotide triplets can be translated into protein, depending
on which nucleotide serves as the starting point
ribosomal RNA (rRNA)
RNA molecule that forms the structural and catalytic core
of the ribosome.
ribosome
Large macromolecular complex, composed of RNAs and
proteins, that translates a messenger RNA into a polypeptide
chain
ribozyme
An RNA molecule with catalytic activity.
RNA capping
The modification of the 5′ end of a maturing RNA transcript
by the addition of an atypical nucleotide
RNA polymerase
Enzyme that catalyzes the synthesis of an RNA molecule from a DNA template using ribonucleoside triphosphate
precursors.
RNA processing
Broad term for the modifications that a precursor mRNA
undergoes as it matures into an mRNA. It typically includes
5′ capping, RNA splicing, and 3′ polyadenylation
RNA splicing
Process in which intron sequences are excised from RNA
molecules in the nucleus during the formation of a mature
messenger RNA.
RNA transcript
RNA molecule produced by transcription that is
complementary to one strand of DNA
small nuclear RNA (snRNA)
RNA molecule of around 200 nucleotides that participates
in RNA splicing.
spliceosome
Large assembly of RNA and protein molecules that splices
introns out of pre-mRNA in the nucleus of eukaryotic cells.
transcription
Process in which RNA polymerase uses one strand of
DNA as a template to synthesize a complementary RNA
sequence.
transfer RNA (tRNA)
Small RNA molecule that serves as an adaptor that “reads”
a codon in mRNA and adds the correct amino acid to the
growing polypeptide chain.
translation
Process by which the sequence of nucleotides in a messenger
RNA molecule directs the incorporation of amino acids into
protein.
translation initiation factor
Protein that promotes the proper association of ribosomes
with mRNA and is required for the initiation of protein
synthesis.
