1. Why cant 1 base make up an amino acid?
    one base per amino acid would only specify 4 amino acids

    4<20: not enough
  2. Why cant 2 bases make up an amino aicd?
    2 bases per amino acid woud only specify 16 amino acids

  3. Why is having 3 bases code for an amino acid good? (2)
    it allows for 64 potential amino acids, more than enough than we need

    *there will be a redundancy because of the possible 64 combinations
  4. Image Upload 1 (1)
    when removing 3 mutation, the sentence made sense again
  5. Image Upload 2 (2)
    • -a 1 base pair or 2 base pair throws the reading frame off
    • *does not produce a functional protein

    -when 3 base pair deletion occurs, the correct reading frame and slightly altered but functional protein can be produced
  6. If we add an insertion of one nucleotide, will we have a crap or functional message?
  7. What is a reading frame?
    sequence of codons
  8. What is the 3 base code known as?
    triplet code
  9. How did Francis Crick and colleagues establish that the code is based on 3 nucleotides for each amino acid?
    by making deletion and insertion mutations in viral DNA
  10. How can the reading frame be destroyed? how can it be restored? (2)
    by adding a mutation; can be restored if the total number of deletions or additions were multiples of 3
  11. Image Upload 3(2)
    -they added bacterial extract with all necessary components with synthetic mRNA strand

    -it produces a polypetide synthesized

    *** UUU-UUU-UUU > Phe-Phe-Phe
  12. Koranas experiments
    Image Upload 4 (2)
    -she repeated 2 letters in groups of 3

    -she saw a pattern

    • *** ACA-CAC-ACA
    •       Thr-His-Thr
  13. Image Upload 5What do stop codons do?
    • they stop the string of mRNA
    • *there a 3 of them
  14. Which 3 amino acids code for stop codon?
  15. Image Upload 6 HWat is the beginning of every strand of DNA in a cell? and what does it define?
    -AUG, Methionine

    - defines the beginning of where to start reading the message
  16. Image Upload 7 Redundancy (2)
    -the first 2 nucleotides tend to be the same, the last nucleotide is the one that differs

    • -UUC and UUC both specify for the same amino acid
    • *changes genotype but not phenotype
    • **most amino acids have multiple codons that code for them
  17. Can amino acids be specify for multiple triplet codons?
    • yes
    • **redundancy
    • *** proline
  18. Image Upload 8Are all amino acids specified in this code?
  19. 4 Characteristics of genetic code
    -it is redundant

    -it is unambiguous

    -it is nearly universal

    -it is conservative
  20. (characteristics of GC) Redundant
    all amino acids except methionine and tryptophan are coded by more than one codon
  21. (characteristics of GC) Unambiguous
    a single codon never codes for more than one amino acid

    ***CCG will always code for proline and only proline
  22. (characteristics of GC) Universal
    • with few minor exceptions, all codons specify the same amino acids in all organisms
    • *code works for us, animals, plants, etc
  23. (characteristics of GC) Conservative
    when several codons specify the same amino acid, first 2 bases are almost always identical

    ***Proline: CC*, CC*, CC*, CC*
  24. Image Upload 9
  25. What is a point mutations?
    • when you take one single nucleotide and do something with it
    • *change it, insert it, take one out
  26. 4 types of point mutations



  27. (types of point mutations) what is a Silent mutation?
    change in nucleotide that does not change amino acid specified by codon Image Upload 10
  28. (types of point mutations) What are consequences for silent mutation?
    -change in genotype but no change in phenotype
  29. What is a mutation?
    change in the genotype
  30. (types of point mutations) what is Missense (replacement)?
    • change in nucleotide that changes amino acid specified by codon
    • Image Upload 11
  31. (types of point mutations) What is the consequence of missense?
    change in primary structure of protein
  32. Is the genotype or phenotype affected by Missense?
    Genotype: yes

    Phenotype : yes, amino acid was replaced
  33. (types of point mutations) What is nonsense?
    • change in nucleotide that results in early stop codon
    • *protein is usually crap
  34. (types of point mutations) What are consequences of nonsense?
    premature termination-polypeptide truncated

    Image Upload 12
  35. (types of point mutations) What is frameshift?
    addition or deletion of a nucleotide

    Image Upload 13
  36. What is consequence of frameshift?
    • reading frame is shifted
    • *massive missense
    • **protein comes out like crap
  37. Does nonsense affect genotype or phenotype?
    Genotype: Yes

    Phenotype: Yes, polypeptide is truncated
  38. Does frameshift affect genotype or phenotype?
    genotype: yes

    phenotype: yes, makes it look like crap
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how genes work