Chapter 14 Flashcards
A modified form of guanine nucleotide added onto the end of a pre-mRNA molecule
5’ cap
One of the ribosome’s three binding sites for tRNA translation. The A site holds the tRNA carrying the next amino acid to be added to the polypeptide chain (A strands for aminoacyl tRNA)
A site
A type of eukaryotic gene regulation at the RNA-processing level I’m which different mRNA molecules are produced from the same primary transcript, depending on which RNA segments are treated as exons and which as introns
Alternative RNA splicing
An enzyme that joins each amino acid to the appropriate tRNA
Aminoacyl-tRNA synthease
A nucleotide triplet at on end of a tRNA molecule that base-pairs with a particular complementary codon on an mRNA molecule
Anticodon
A three-nucleotide sequence of DNA or mRNA that specifies a particular amino acid or termination signal; the basic unit of the genetic code.
Codon
A mutational loss of one or more nucleotide pairs from a gene.
Deletion
One of a ribosome’s three binding sites for tRNA during translation. The E site is the place where discharged tRNAs leave the ribosome. (E stands for exit.)
E site
A sequence within a primary transcript that remains in the RNA after RNA processing; also refers to the region of DNA from which this sequence was transcribed.
Exon
A mutation occurring when nucleotides are inserted in or deleted from a gene and the number inserted or deleted is not a multiple of three, resulting in the improper grouping of the subsequent nucleotides into codons.
Frameshift mutation
The process by which information encoded in DNA directs the synthesis of proteins or, in some cases, RNAs that are not translated into proteins and instead function as RNAs.
Gene expression
A mutation involving the addition of one or more nucleotide pairs to a gene.
Insertion
A noncoding, intervening sequence within a primary transcript that is removed from the transcript during RNA processing; also refers to the region of DNA from which this sequence was transcribed.
Intron
A type of RNA, synthesized using a DNA template, that attaches to ribosomes in the cytoplasm and specifies the primary structure of a protein. (In eukaryotes, the primary RNA transcript must undergo RNA processing to become mRNA.)
Messenger RNA
A nucleotide-pair substitution that results in a codon that codes for a different amino acid.
Missense mutation
A chemical or physical agent that interacts with DNA and can cause a mutation.
Mutagen
A change in the nucleotide sequence of an organism’s DNA or in the DNA or RNA of a virus.
Mutation
A mutation that changes an amino acid codon to one of the three stop codons, resulting in a shorter and usually nonfunctional protein.
Nonsense mutation
A type of point mutation in which one nucleotide in a DNA strand and its partner in the complementary strand are replaced by another pair of nucleotides.
Nucleotide-pair substitution
One of a ribosome’s three binding sites for tRNA during translation. The P site holds the tRNA carrying the growing polypeptide chain. (P stands for peptidyl tRNA.)
P site
A change in a single nucleotide pair of a gene
Point mutation
A sequence of 50–250 adenine nucleotides added onto the 3′ end of a pre-mRNA molecule.
Poly-A tail
An initial RNA transcript from any gene; also called pre-mRNA when transcribed from a protein-coding gene.
Primary transcript
A specific nucleotide sequence in the DNA of a gene that binds RNA polymerase, positioning it to start transcribing RNA at the appropriate place.
Promoter
On an mRNA, the triplet grouping of ribonucleotides used by the translation machinery during polypeptide synthesis
Reading frame
RNA molecules that, together with proteins, make up ribosomes; the most abundant type of RNA.
Ribosomal RNA
A complex of rRNA and protein molecules that functions as a site of protein synthesis in the cytoplasm; consists of a large subunit and a small subunit. In eukaryotic cells, each subunit is assembled in the nucleolus. See also nucleolus
Ribosome
An RNA molecule that functions as an enzyme, such as an intron that catalyzes its own removal during RNA splicing
Ribozyme
An enzyme that links ribonucleotides into a growing RNA chain during transcription, based on complementary binding to nucleotides on a DNA template strand.
RNA polymerase
Modification of RNA primary transcripts, including splicing out of introns, joining together of exons, and alteration of the 5′ and 3′ ends.
RNA processing
After synthesis of a eukaryotic primary RNA transcript, the removal of portions of the transcript (introns) that will not be included in the mRNA and the joining together of the remaining portions (exons).
RNA splicing
A sequence of about 20 amino acids at or near the leading (amino) end of a polypeptide that targets it to the endoplasmic reticulum or other organelles in a eukaryotic cell.
Signal peptide
A protein-RNA complex that recognizes a signal peptide as it emerges from a ribosome and helps direct the ribosome to the endoplasmic reticulum (ER) by binding to a receptor protein on the ER
Signal-recognition particle (SRP)
A nucleotide-pair substitution that has no observable effect on the phenotype; for example, within a gene, a mutation that results in a codon that codes for the same amino acid.
Silent mutation
A large complex made up of proteins and RNA molecules that splices RNA by interacting with the ends of an RNA intron, releasing the intron and joining the two adjacent exons.
Spliceosome
In transcription, the nucleotide position on the promoter where RNA polymerase begins synthesis of RNA.
Start point
A DNA sequence in eukaryotic promoters crucial in forming the transcription initiation complex.
TATA box
The DNA strand that provides the pattern, or template, for ordering, by complementary base pairing, the sequence of nucleotides in an RNA transcript.
Template strand
In bacteria, a sequence of nucleotides in DNA that marks the end of a gene and signals RNA polymerase to release the newly made RNA molecule and detach from the DNA.
Terminator
The synthesis of RNA using a DNA template.
Transcription
A regulatory protein that binds to DNA and affects transcription of specific genes.
Transcription factor
The completed assembly of transcription factors and RNA polymerase bound to a promoter.
Transcription initiation complex
A region of DNA that is transcribed into an RNA molecule
Transcription Unit
An RNA molecule that functions as a translator between nucleic acid and protein languages by picking up a specific amino acid and carrying it to the ribosome, where the tRNA recognizes the appropriate codon in the mRNA.
Transfer RNA
The synthesis of a polypeptide using the genetic information encoded in an mRNA molecule. There is a change of “language” from nucleotides to amino acids.
Translation
A genetic information system in which a series of three-nucleotide-long words specifies a sequence of amino acids for a polypeptide chain.
Triplet code
Flexibility in the base-pairing rules in which the nucleotide at the 5′ end of a tRNA anticodon can form hydrogen bonds with more than one kind of base in the third position (3′ end) of a codon.
Wobble
