Biology Chapter 17

  1. What is the usual flow of genetic information?
    inherited DNA leads to phenotypes by directing synthesis of proteins
  2. What is the Central Dogma of Biology?
    DNA --> transcription --> RNA --> translation--> Protein
  3. What is gene expression?
    the process by which DNA directs protein (or RNA) synthesis
  4. What are genes composed of and how many kinds of these components are there?
    • nucleotides
    • four
  5. What are proteins composed of and how many kinds of these component are there?
    • amino acids
    • twenty
  6. What are the three major types of RNA?
    mRNA messenger: brings info for protein production from genes to ribosome

    tRNA transfer: brings amino acids that are used to build new proteins into ribosome

    rRNA ribosomal: structural component of ribosomes
  7. Define and name function:
    RNA polyerase
    a sequence within a primary transciprt that remains in the RNA after RNA processing -- coding regions

    a specific nucleotide sequence in DNA that binds RNA polymerase, positioning it to start transcribing RNA at the appropriate place

    an enzyme that links ribonucleotides into a griowing RNA chain during transcription

    a complex of rRNA and protein molecules that function as a site of protein syntheses in the cytoplasm, consists of large and small subunit, assembled in the nucleolus.
  8. Describe hypotheses:
    one gene - one enzyme
    one gene - one protein
    one gene - many phenotypes
    function of one gene is to produce one enzyme

    one gene produces a polypeptide chain

    last one is correct! controlled by proteins or other types of molecules as well as interactions
  9. What is alternative splicing? Why is it important?
    A type of eukaryotic gene regulation at the RNA-processing level in which different mRNA molecules are produced from the same primary transcript, depending on which RNA segnemts are treated as exons and which as introns.

    It allows more than one protein to be produced by a single gene.
  10. transcription vs. translation
    the synthesis of RNA using a DNA template

    the synthese of a polypeptide using the genetic information encoded in the mRNA molecule ... change of "language" from nucleotides to amino acids
  11. What is the genetic code?

    What is a codon?
    the language that translates nucleotide bases to proteins

    a three nucleotide sequence of DNA or mRNA that signifies a particular amino acid or termination signal; the basic unit of the genetic code
  12. Transcription:
    major players?

    • promoter
    • RNA polymerase
    • mRNA
  13. promoter
    a specific nucleotide sequence in DNA that binds RNA polymerase, positioning it to start transcribing RNA at the appropriate place
  14. RNA polymerase
    an enzyme that links ribonucleotides into a growing RNA chain during transcription
  15. messenger RNA (mRNA)
    type of RNA, synthesized using a DNA template, that attahces to ribosomes in the cytoplasm and specifies the promary structure of a protein
  16. transcription factor
    a regulatory protein that binds to DNA and affects transcription of specific genes
  17. What are the stages of transcription?
    initiation: RNA polymerase binds to promoter > DNA strands unwind > RNA polymerase builds RNA

    elongation: RNA P moves downstream adding ribonucleotides from 5' to 3' > DNA strand rewinds after RNA P passes

    termination: RNA transcript (mRA) is released and RNA Polymerase detaches from DNA
  18. What are introns?
    non-coding, intervening sequences within primary transcript that is removed from the transcript during RNA processing; the region of DNA from which this sequence was transcribed
  19. coding strand

    template strand
    mirrors the mRNA sequence

    strand that provides the pattern for the ordering of sequence of nucleotides in a RNA transcript
  20. RNA processing
    modification of RNA transcripts, including splicing out of introns, joining together of exons, and alteration of 5' and 3' ends
  21. 5' cap
    a modified form of guanine nucleotide added onto the nucleotide at the 5' end of a pre-mRNA molecule
  22. poly-A tail
    a sequence of 50 to 250 adenine nucleotides added onto the 3' end of a pre-mRNA molecule
  23. translation:
    major players?
    • occurs in cytoplasm for use within the cell
    • occurs in rough ER for outside or plasma memberbrane

    • ribosome
    • tRNA
    • codons
    • polypeptide
  24. ribosome
    • rRNA-protein complex
    • made up a large and small subunits that assemble at the mRNA
  25. tRNA
    an RNA molecule that functions as an interpreter between nucleic acid and protein language by picking up specfic amino acids and recognizing the appropriate codons in the mRNA

    loops form due to base pairing within the molecule

    anticodon binds with complementary codon on mRNA
  26. polypeptide
    amino acid sequence that will eventually becone the final protein product
  27. stages of translation?
    initiation: initiator tRNA binds methionine and the corresponding codon on the mRNA ( AUG) > large subunit of ribosome binds to small unit

    elongation: aminio acids are added one by one to the chain

    termination: ribosome eventually reaches a stop codon (UAG, UAA, UGA) in the mRNA > translation apparatus breaks apart
  28. sites of the transcription unit
    P site: processing: peptide bond forms adding amino acid to the chain

    A site : accepts tRNA with the next amino acid

    E site: exiting: empty tRNA moves to this site and then is released
  29. What is a point mutation?
    a change in a gene at a single nucleotide pair
  30. 3 types of point mutations
    base pair substitution: the replacement of one nucleotide and its partner in the complementary DNA strand by another pair of nucleotides

    insertion: a mutation involving the addition of one or more nucleotide pairs to a gene

    deletion: a mutation involving the deletion of one or more nucluotide pairs in a gene
  31. non synonmyous vs synonmyous mutations
    synonmyous is silent, no change in protein produced
  32. three types of non synonmyous mutations
    missense: a base pair substitution that results on a codon that codes for a different amino acid

    nonsense: a mutuation that changes an amino acid codon to one of the stop codons, resulting in a shorter and usually nonfunctinal protein

    frameshift: mutation occurring when the number of nucleotides inserted or deleted is not a multiple of three, resulting in the improper groupin os the subsequent nucleotides into codons
  33. Definitions of a GENE
    a DNA sequence that codes for a phenotype

    a region of DNA that can produce a functional product
Card Set
Biology Chapter 17
chap 17