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Chapter 17 Vocab
gene expression
29
Biology
12th Grade
08/23/2008

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Term
gene expression
Definition
conversion of the information encoded in a gene first into messenger RNA and then to a protein
Term
transcription
Definition
the synthesis of RNA on a DNA template
Term
messenger RNA
Definition
type of RNA, synthesized from DNA that attaches to ribosomes in the cytoplasm and specifies the primary structure of a protein
Term
translation
Definition
the synthesis of a polypeptide using the genetic information encoded in an mRNA molecule
Term
ribosome
Definition
a cell organelle constructed in the nucleolus and functioning as the site of protein sythesis in the cytoplasm; consists of rRNA and protein molecules
Term
primary transcript
Definition
an initial RNA transcrip; also called pre-mRNA
Term
triplet code
Definition
a set of three-nucleotide long words that specify the amino acids for polypeptide chains
Term
template strand
Definition
the DNA strand that provides the template for ordering the sequence of nucleotides in an RNA transcript
Term
codon
Definition
a three-nucleotide sequence of DNA or mRNA that specifies a particular amino acid or termination signal; the basic unit of a genetic code
Term
reading frame
Definition
the way a cell's mRNA-translating machinery groups the mRNA nucleotides into codons
Term
RNA polymerase
Definition
an enzyme that links together the growing chain of ribo-nucleotides during transcription
Term
promoter
Definition
a specific nucleotide sequence in DNA that binds RNA polymerase and indicates where to start transcribing RNA
Term
terminator
Definition
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
Term
initiation
Definition
start of a chemical or enzymatic reaction
Term
elongation
Definition
Term
translocation
Definition
an aberration in chromosome structure resulting from an error in meiosis or from mutagens; specifically, attachment of a chromosomal fragment to a nonhomologous chromosome
Term
termination
Definition
stop of mRNA synthesis at the terminator site
Term
introns
Definition
a noncoding, intervening sequence within a eukaryotic gene
Term
exons
Definition
a coding region of a eukaryotic gene. Exons, which are expressed, are separated from each other by introns
Term
transfer RNA
Definition
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
Term
anicodon
Definition
a specialized base triplet at one end of a tRNA molecule that recognizes a particular complementary codon on an mRNA molecule
Term
ribosomal RNA
Definition
the most abundant type of RNA, which together with proteins, forms the structure of ribosomes. Ribosomes coordinate the sequential coupling of tRNA molecules to mRNA codons
Term
polysomes
Definition
a complex of ribosomes strung along a single strand of messenger RNA that translates the genetic information coded in the messenger RNA during protein sythesis
Term
base-pair substitution
Definition
a point mutation; the replacement of one nucleotide and its partner in the complementary DNA strand by another pair of nucleotides
Term
insertions
Definition
a mutations involving the addition of one or more nucleotide pairs to a gene
Term
deletions
Definition
a deficiency in a chromosome resulting from the loss of a fragment through breakage; a mutational loss of one or more nucleotide pairs from a gene
Term
nonsense mutation
Definition
a mutation that changes an amino acid codon to one of the three stop codons, resulting in a shorter and usually nonfunctional protein
Term
frameshift mutation
Definition
a mutation occurring when the number of nucleotides inserted or deleted is not a multiple of 3, resulting in the improper grouping of the following nucleotides into codons
Term
mutagens
Definition
a chemical or physical agent that interaccts with DNA and causes a mutation
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