| Term | Definition |
|---|
| one gene-one enzyme hypothesis | the function of a gene is to dictate the production of a specific enzyme |
| one gene-one polypeptide hypothesis | the premise that a gene is a segment of DNA that codes for one polypeptide |
| transcription | ________ is the synthesis of RNA under the direction of DNA |
| messenger RNA | carries genetic message from the DNA to the protein-synthesizing machinery of the cell |
| translation | _________ is the actual synthesis of a polypeptide, which occurs under the direction of mRNA |
| ribosomes | the sites of translation are __________, complex particles that facilitate the orderly linking of amino acids into polypeptide chains |
| RNA processing | modification of RNA before it leaves the nucleus |
| primary transcript | initial RNA transcript; AKA pre-mRNA when transcribed from a protein-coding gene |
| triplet code | the genetic instructions for a polypeptide chain are written in the DNA as a series of nonoverlapping, three-nucleotide words |
| template strand | the DNA strand that provides the template for ordering the sequence of nucleotides in an RNA molecule |
| codons | the mRNA base triplets are called ______, and they are most commonly written in the 5' --> 3' direction |
| reading frame | the way a cell's mRNA-translating machinery groups the mRNA nucleotides into codons |
| RNA polymerase | an enzyme that pries the 2 strands of DNA apart and hooks together the RNA nucleotides as they base pair along the DNA template |
| promoter | the DNA sequence where DNA polymerase attaches and initiates transcription is known as the ________ |
| terminator | in prokaryotes, the sequence that signals the end of transcription is called the ____________ |
| transcription unit | the stretch of DNA that is transcribed into an RNA molecule is called a __________ ________ |
| transcription factors | in eukaryotes, a collection of proteins called __________ __________ mediate the binding of RNA polymerase and the initiation of transcription |
| transcription initiation complex | the completed assemble of the transcription factors and RNA polymerase II bound to the promoter is called a ___________ __________ _________ |
| TATA box | a promoter DNA sequence crucial in forming the transcription initiation complex |
| RNA splicing | in the eukaryotic nucleus, the removal of a large portion of the RNA molecule that is initially synthesized is called _____ _________ |
| introns | a non-coding, intervening sequence within a eukaryotic gene |
| exons | a coding region of a eukaryotic gene; when expressed, they are separated from each other by introns |
| small nuclear ribonucleoproteins | (snRNPs) recognize splice sites; are composed of RNA, protein molecules |
| spliceosome | several difference snRNPs join with additional proteins to form an even larger assemble called a ________, which interacts with certain sites along an intron, releasing the intron and joining together the two exons flanked by the intron |
| ribozymes | RNA molecules that function as enzymes |
| alternative RNA splicing | a number of genes are known to give rise to two or more different polypeptides, depending on which segments are treated as exons during RNA processing |
| domains | proteins often have a modular architecture consisting of discrete structural and functional regions called ________ |
| exon shuffling | the presence of introns in a gene may facilitate the evolution of new and potentially useful proteins as a result of a process known as _______ _________ |
| transfer RNA | the message is a series of codons along an mRNA molecule, and the interpreter is called ________ ___ |
| anticodon | at the other end of the tRNA is a nucleotide triplet called a _________, which base-pairs with a complementary codon on mRNA |
| aminoacyl-tRNA synthetase | each amino acid is joined to the correct tRNA by a specific enzyme called an __________ -____ __________ |
| wobble | a violation of the base-pairing rules in that the third nucleotide (5' end) of a tRNA anticodon can form hydrogen bonds with more than 1 kind of base in the third position (3' end) of a codon |
| ribosomal RNA | a ribosome is made up of 2 subunits, called the large and small subunits, which are constructed of proteins and RNA molecules called __________ ___ |
| P site; A site | the _ ____ (peptidyl-tRNA site) holds the mRNA carrying the growing polypeptide chain, whih the _ ____ (aminoacyl-tRNA site) holds the tRNA carrying the next amino acid to be added to the chain |
| E site | discharged tRNAs leave the ribosome from the _ ____ |
| polyribosomes | strings of ribosomes |
| post-translation modification | certain amino acids may be chemically modified by attachment of sugars, lipids, phosphatae groups, other additives |
| signal peptide | polypeptide of proteins destined for endomembrane system or for secretion are marked by a _______ ________, which targets the proteins to the ER |
| signal-recognition particle | the single peptide is recognized as it emerges from the ribosome by a protein-RNA complex called ______-________ _________ (SRP) |
| mutations | _________ are changes in the genetic material of a cell or virus |
| point mutations | chemical changes in just one base pair of a gene |
| base-pair substitution | a _____-______ __________ is the replacement of one nucleotide and its partner with another pair of nucleotides |
| missense mutations | substitution mutations are usually ________ ________, the altered codon still codes for an amino acid |
| nonsense mutation | a mutation that changes an amino acid codon to one of the 3 stop codons, resulting in a shorter and usually nonfunctional protein |
| insertions; deletions | _________ and _________ are additions or losses of nucleotide pairs in genes |
| frameshift mutation | a mutation occuring 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 |
| mutagens | a number of physical and chemical agents, called _______, intereact with DNA in ways and cause mutations |
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