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1
Q

how are codons read?

A

amino acids have to be ‘activated’ before incorporation in a protein
the activated form of the amino acid is attached to small RNA (tRNA)

2
Q

transfer RNA

A

(tRNA) small RNA

  • adaptors between codons and amino acids
  • two ‘readings’: addition of correct amino acid to tRNA and antiparallel base pairing between codon in mRNA and anticodon in tRNa
  • each tRNA can recognize multiple codons
  • made from genes
  • a mutation in a tRNA gene can alter the anticodon
3
Q

aminoacyl-tRNA synthetastes

A
  • attach amino acids to tRNAs
  • reaction: aa + ATP + tRNA -> aminoacylated tRNA
  • each amino acid has its own tRNA synthetase
4
Q

wobble phenomenon

A
  • base pairing rules are relaxes at 5’ position of anticodon
  • contributions of relaxed rules: RNA structure and modified nucleotides in tRNA
  • 5’ base of anticodon is modified
  • I can pair with U, C or A
5
Q

is it possible to have mutant tRNAs that suppress missense mutations?

A

yes but these are very unhealthy since many proteins will have incorrect amino acids from ‘misreading’ of the code

6
Q

silent mutation

A

change in base pair that codes for the same amino acid

7
Q

missense mutation

A

change in base pair codes for a different amino acid

8
Q

nonsense mutation

A

change in base pair codes for stop codon

9
Q

frameshift mutation

A

insertion/deletion of base pair causes next amino acids to change

10
Q

genetic approach to understanding gene function

A
  • mutate gene
  • observe mutant phenptype
  • infer wildtype function
11
Q

loss of function alleles

A
  • usually recessive to wild type
    amorph: null allele
    hypomorph: weak allele
12
Q

gain of function alleles

A

*usually dominant to wild type
hyper morph: overactive
anti morph: dominant negative
neomorph: new function

13
Q

amorph

A

no gene product, or no functional gene product

14
Q

hypomorph

A

less of wild type gene product, or mutant gene product with less activity than normal gene product

15
Q

a nonsense mutant would most likely be a:

a. hypomorph
b. amorph

A

amorph

16
Q

hypermorphs

A
  • excess wildtype gene product
  • mutant gene product with increased activity
  • mutations can be in the coding region or regulatory regions
17
Q

antimorph

A
  • mutant gene product that prevents the wildtype gene product working
  • antimorphic mutations are usually in the ORF
18
Q

neomorph

A
  • mutant gene product
  • wildtype gene product in new context
  • neomorphic mutations can be in the ORF or in a regulatory region
19
Q

deletion of a gene would probably be which type of mutant?

a. hypomorph
b. amorph
c. hypermorph
d. anti morph
e. neomorph

A

amorph