Chapter 17 From Gene to protein

  1. gene expression
    process by which DNA directs synthesis of proteins or RNA
  2. ribosome
    site of translationfacilitate orderly linking of amino acids into polypeptide chains
  3. template strand
    the strand of DNA that is transcribed.

    Only one strand of the double helix is transcribed at a time, and generally it is always the same strand that is transcribed.
  4. start point
    nucleotide where RNA synthesis actually begins
  5. Termination
    prokaryotesterminator sequence in DNA
  6. RNA processing
    Modification of pre-mRNA that allow transcript to exit nuclear envelope.

    5' Cap addedPoly-A tail addedThese facilitate exiting the nuclear envelopeprotect against degradation by hydrolytic enzymeshelp ribosomes attach to 5' end of mRNA.

    RNA splicing removes noncoding RNA
  7. introns
    aka intervening sequencesnoncoding segments of nucleic acid that lie between coding regions
  8. anticodon
    nucleotide triplet at end end of a tRNAbase-pairs with complementary codon on mRNA
  9. point mutation
    changes in a single nucleotide pair of a genemay be invisible if it results in production of the same amino acid
  10. nonsense mutation
    substitution of stop codon for an amino acid codon.

    results in early termination of translationnearly always produces nonfunctional protein
  11. transcription
    The synthesis of RNA using a DNA template.
  12. codon
    mRNA nucleotide tripletwritten in 5' to 3' direction
  13. transcription unit
    A region of DNA that is transcribed into an RNA molecule.
  14. 5' cap
    modified form of guanine nucleotide added to 5' end after transcription of the first 20-40 nucleotides performed by enzymes
  15. exon
    A sequence within a primary transcript that remains in the RNA after RNA processing; also refers to the region of DNA from which this sequence was transcribed.
  16. wobble
    base pairing at third position of mRNA codon does not necessarily have to be exact.

    • tRNA: 3' - UCU - 5' can bind with either
    • mRNA: 5' - AGA - 3' or
    • mRNA: 5' - AGG - 3'
  17. E site
    One of a ribosome's three binding sites for tRNA during translation. The E site is the place where discharged tRNAs leave the ribosome. (E stands for exit.)
  18. silent mutation
    A nucleotide-pair substitution that has no observable effect on the phenotype; for example, within a gene, a mutation that results in a codon that codes for the same amino acid.
  19. insertion
    A mutation involving the addition of one or more nucleotide pairs to a gene.
  20. translation
    The synthesis of a polypeptide using the genetic information encoded in an mRNA molecule. There is a change of “language” from nucleotides to amino acids.
  21. promoter
    A specific nucleotide sequence in the DNA of a gene that binds RNA polymerase, positioning it to start transcribing RNA at the appropriate place.
  22. Terminator
    in prokaryotesDNA sequence that signals the end of transcription
  23. Poly-A tail
    addition of 50-250 Adenine nucleotides
  24. ribozyme
    An RNA molecule that functions as an enzyme, such as an intron that catalyzes its own removal during RNA splicing.
  25. ribosomal RNA
  26. polyribosomes
    string of ribosomes along a single strand of mRNA, thus creating many copies of the peptide at once
  27. triplet code
    A genetic information system in which a set of three-nucleotide-long words specify the amino acids for polypeptide chains.

    the code of three nucleotides, occurring in sequence, that comprise an amino acid.

    The sequence of bases can then be read as nonoverlapping sets of triplets, each of which id's an amino acid.

    Some triplets code for like amino acidsOthers code for stop or startbuilds in redundancy but not ambiguity
  28. elongation
    RNA polymerase moves along DNA, untwisting the double helixexposes 10-20 bp at a timereads DNA 3' to 5'builds RNA 5' to 3'in the wake of RNA poly II, the transcript peels away from the template and then the double helix reforms
  29. transcription factor
    A regulatory protein that binds to DNA and affects transcription of specific genes.
  30. mutation
    A change in the nucleotide sequence of an organism's DNA or in the DNA or RNA of a virus.
  31. frameshift mutation
    A mutation occurring when nucleotides are inserted in or deleted from a gene and the number inserted or deleted is not a multiple of three, resulting in the improper grouping of the subsequent nucleotides into codons.
  32. nucleotide-pair substitution
    replacement of one nucleotide and its partner with another pair of nucleotidestypically missense
  33. transfer RNA (tRNA)
    An RNA molecule that functions as a translator between nucleic acid and protein languages by carrying specific amino acids to the ribosome, where they recognize the appropriate codons in the mRNA.
  34. RNA splicing
    cut-and-paste that removes large portions of original pre-mRNA transcript.

    decreased from ~27,000 to ~1,200 nucleotidesremoves introns, splices exons
Card Set
Chapter 17 From Gene to protein
From Gene to Protein