42 terms

Chapter 17 Vocabulary AP Bio

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5' cap
The end of a pre-mRNA molecule modified by the addition of a cap
A site
One of a ribosome's three binding sites for tRNA during translation. Holds the tRNA carrying the next amino acid to be added to the polypeptide chain.
anticodon
A specialized base triplet at one end of a tRNA molecule that recognizes a particular complementary codon on an mRNA molecule.
base-pair substitution
A type of point mutation; the replacement of one nucleotide and its partner in the complementary DNA strand by another pair of nucleotides.
codon
A three-nucleotide sequence of DNA or mRNA that specifies a particular amino acid or termination signal; the basic unit of the genetic code.
deletion
1) A deficiency in a chromosome resulting from the loss of a fragment through breakage. (2) A mutational loss of one or more nucleotide pairs from a gene.
E site
One of a ribosome's three binding sites for tRNA during translation. The place where discharged tRNAs leave the ribosome.
exon
A coding region of a eukaryotic gene or expressed region
frameshift mutation
A mutation occurring when the number of nucleotides inserted or deleted is not a multiple of three, resulting in the improper grouping of the following nucleotides into codons.
insertion
A mutation involving the addition of one or more nucleotide pairs to a gene.
intron
A noncoding, intervening sequence within a eukaryotic gene.
messenger RNA (mRNA)
A type of RNA, synthesized from DNA, that attaches to ribosomes in the cytoplasm and specifies the primary structure of a protein.
missense mutation
The most common type of mutation, a base-pair substitution in which the new codon makes sense in that it still codes for an amino acid.
mutagen
A chemical or physical agent that interacts with DNA and causes a mutation.
mutation
A rare change in the DNA of a gene, ultimately creating genetic diversity.
nonsense mutation
A mutation that changes an amino acid codon to one of the three stop codons, resulting in a shorter and usually nonfunctional protein
one gene-one polypeptide hypothesis
The premise that a gene is a segment of DNA that codes for one polypeptide.
P site
One of a ribosome's three binding sites for tRNA during translation. Holds the tRNA carrying the growing polypeptide chain. (P stands for peptidyl tRNA
point mutation
A change in a gene at a single nucleotide pair
poly-A tail
The modified end of the 3' end of an mRNA molecule consisting of the addition of some 50 to 250 adenine nucleotides.
primary transcript
An initial RNA transcript; also called pre-mRNA when transcribed from a protein-coding gene
promoter
A specific nucleotide sequence in DNA that binds RNA polymerase and indicates where to start transcribing RNA
ribosome
A cell organelle constructed in the nucleolus and functioning as the site of protein synthesis in the cytoplasm; consists of rRNA and protein molecules, which make up two subunits.
ribozyme
An enzymatic RNA molecule that catalyzes reactions during RNA splicing.
RNA polymerase
An enzyme that links together the growing chain of ribonucleotides during transcription.
RNA processing
Modification of RNA before it leaves the nucleus, a process unique to eukaryotes.
RNA splicing
The removal of noncoding portions (introns) of the RNA molecule after initial synthesis.
signal-recognition particle (SRP)
A protein-RNA complex that recognizes a signal peptide as it emerges from the ribosome.
spliceosome
A complex assembly that interacts with the ends of an RNA intron in splicing RNA, releasing the intron and joining the two adjacent exons.
TATA box
A promoter DNA sequence crucial in forming the transcription initiation complex.
template strand
The DNA strand that provides the template for ordering the sequence of nucleotides in an RNA transcript.
terminator
In prokaryotes, a special sequence of nucleotides in DNA that marks the end of a gene. It signals RNA polymerase to release the newly made RNA molecule, which then departs from the gene.
transcription
The synthesis of RNA on a DNA template.
transcription unit
A region of a DNA molecule that is transcribed into an RNA molecule.
transfer RNA (tRNA)
An RNA molecule that functions as an interpreter between nucleic acid and protein language by picking up specific amino acids and recognizing the appropriate codons in the mRNA.
translation
The synthesis of a polypeptide using the genetic information encoded in an mRNA molecule. There is a change of languagefrom nucleotides to amino acids
anti-
opposite ex: anticodon
exo-
out, outside, without
intro-
within ex: intron
poly-
many
trans-
across ex:transcription
-script
write ex: transcription