Ch 6A ID Terms

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DesLee26
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295695
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Ch 6A ID Terms
Updated:
2015-02-15 13:14:36
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Sam
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MolecularTestTwo
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Test Two
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  1. transcription
    First part in reading a needed part of genetic instructions; particular portion of DNA sequence is copied to create an RNA copy; several RNA copies can be made from the same gene in a short time period
  2. RNA polymerases
    Catalyze formation of phosphodiester bonds that link nucleotides together to form a linear chain; moves along DNA, unwinding the helix to expose new regions of the template; goes in 53 direction; the substrates are nucleoside triphosphates (ATP, CTP, UTP, and GTP); hydrolysis of high-energy bonds provides energy needed
  3. mRNA
    RNA molecules that are copied from gees that specify the amino acid sequence of proteins
  4. transcription unit
    Each transcribed segment of DNA; carries the information of just one gene, and therefore codes for either a single RNA molecule or a single protein (or group of related proteins if spliced)
  5. consensus nucleotide sequence
    Derived by comparing many sequences with the same basic function and tallying up the most common nucleotide found at each position; average of large numbers of individual nucleotide sequences
  6. General transcription factors (TF)
    RNA polymerase II requires them to help position it correctly at the promoter; they aid in pulling the two DNA strands apart to allow transcription to begin, and release RNA polymerase from the promoter into the elongation mode once transcription has begun

    General beause they are needed at nearly all promoters used by RNA polymerase II; consisting of a set of interacting proteins, they are designated as TFII and a letter (ex: TFIIB)
  7. TATA box
    Sequence of A and T nucleotides located in the promoter sequence; can be 25 nucleotides upstream from start of transcription
  8. CTD
    C-terminal domain; consists of 52 tandem repeats of a 7-amino acid sequunece, which extend from the RNA polymerase core structure; During transcription initiation, the serine located at the fifth position in the repeat sequence is phosphorylated by TFIIH, which has a protein kinase
  9. Elongation factors
    Proteins that decrease the likelihood that RNA polymerase will dissociate before it reaches the end of a gene; associate shortly after initiation and help polymerases move through different DNA sequences
  10. DNA supercoiling
    A conformation that DNA adopts in response to superhelical tension; conversely, creating varioius loops or coils can do this; can also be caused by RNA polymerase since DNA is anchored and the polymerase can’t rotate
  11. DNA gyrase
    In bacteria, this specialized topoisomerase uses the energy of ATP hydrolysis to pump supercoils continuously into the DNA, thereby maintaining the DNA under constant tension; makes opening of the helix in bacteria favorable in supercoiled DNA
  12. Negative supercoils
    Have opposite handedness from the positive supercoils that form when a region of DNA helix opens. ; they are removed whenever a region of helix opens
  13. RNA splicing
    Joins together the different portions of a protien coding sequence and provides higher eucaryotes with the ability to synthesize different proteins from the same gene; introns are removed; it does this in pre-mRNA
  14. 5' methyl cap
    Signifies the 5’ end of euckaryotic mRNA and helps cell to distinguish mRNAs from other types
  15. Cap-binding complex
    In the nucleus, the 5’ cap binds this protein complex
  16. Spliceosome
    The largest assembly of RNA and protein molecules that performs pre-mRNA splicing in the cell
  17. exon junction complex
    Proteins that mark the site of a successful splicing event and influence the fate of the mRNA
  18. Trans-splicing
    Few eukaryotes exhibit this; exon from two separate RNA transcripts are spliced together to form a mature mRNA molecule; uses a unique snRNP (SL RNP)
  19. hnRNPs
    Proteins that assemble on pre-mRNA molecules as they emerge from transcribing RNA polymerases; some of these unqind hairpin helices from the RNA so splicing is easier. Others package the RNA contained in the very long intron sequences
  20. nuclear transport receptors
    Macromolecules are moved through nuclear pore complexes through this; gets loaded onto mRNA and takes place in concert with 3’ cleavage and polyadenylation; dissociates after helping to move RNA molecule through nuclear pore complex

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