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BIO Chapter 17
Gene Expression: from Gene to Protein
Term | Definition |
---|---|
Transcription- | the synthesis of RNA using information in the DNA |
Messenger RNA- | carries a message from the DNA to protein-synthesizing machinery in the cell |
Translation- | synthesis of polypeptides using the information from mRNA |
Ribosomes- | the sites of translation, molecular complexes that facilitate the orderly linking of amino acids into polypeptide chains |
Primary transcript- | the initial RNA transcript from any gene |
Codon- | the mRNA nucleotide triplets |
Triplet code- | the genetic instructions for a polypeptide chain are written in the DNA as a series of non-overlapping three-nucleotide words |
Template strand- | provides the pattern for the sequence of nucleotides in an RNA transcript |
RNA polymerase- | pries the two strands of DNA apart and joins together RNA nucleotides complimentary to the template strand |
Transcription step one- | initiation |
Transcription step two- | elongation |
Transcription step three- | termination |
Initiation- | after RNA polymerase binds to the promoter, the DNA strands unwind, and the polymerase initiates RNA synthesis at the start point on the template strand |
Elongation- | The polymerase moves downstream, unwinding the DNA and elongating the RNA transcript 5’ to 3’. DNA reform in double helix |
Termination- | eventually, the RNA transcript is released, and the polymerase detaches from the DNA |
Promoter- | the DNA sequence where RNA polymerase attaches and initiates transcription |
Terminator- | the sequence that signals the end of transcription |
Transcription unit- | the stretch of DNA downstream from the promoter that is transcribed into an RNA molecule |
A eukaryotic promoter- | no answer |
Transcription factors- | mediate the binding of RNA polymerase and the initiation of transcription |
TATA box- | crucial promoter DNA sequence |
Transcription initiation complex- | The whole complex of transcription factors and RNA polymerase II bind to it |
Start point- | the nucleotide where RNA synthesis actually begins |
RNA splicing- | the removal of large portions of the RNA molecule that is initially synthesized |
Introns- | the noncoding segments of nucleic acid that lie between coding regions |
Exons- | the coding segments of nucleic acid |
Spliceosome- | the removal of introns is accomplished by a large complex made of protein and RNA |
Alternative RNA splicing- | many genes give rise to two or more polypeptides depending on which segments are exons during RNA processing |
Transfer RNA- | transfer amino acids from cytoplasmic pool of amino acids to a growing polypeptide |
Anticodon- | specific nucleotide triplet that base pairs to a specific mRNA codon |
Ribosomal RNA- | what makes up the small and large subunit of a ribosome |
P site- | holds tRNA carrying the growing polypeptide chain |
A site- | holds the tRNA carrying the next amino acid to be added to the chain |
E site- | discharged tRNA’s leave from here |
Codon recognition- | anticodon of an incoming aminoacyl tRNA base-pairs with the complimentary mRNA codon in the A site |
Peptide bond formation- | rRNA molecule in the large subunit catalyzes the formation of a peptide bond |
Translocation- | ribosome translocates the tRNA in the A site to the B site |
Elongation (translation)- | tRNA that compliments codon move into the A site bringing with it the proper amino acids, translocation, peptide bond forms between amino acids |
Termination of translation- | release factor binds to stop codon, all components of translation assembly are released, ribosomal subunits fall away, RNA gets translated, all parts get reused |
Polyribosome- | multiple work on the same mRNA at the same time, folding and modification of polypeptide chains |
Point mutations- | effect a few small changes in a few nucleotides, change phenotype substitution point mutation |