A codon is an mRNA sequence consisting of 3 nucleotides that codes for an amino acid. Each position can be made up of any 4 nucleotides (A, U, G, C); therefore, there are a total of 64 (4 x 4 x 4) different codons that can be created but they only code for 20 amino acids. This is explained by the wobble phenomenon. One codon for leucine is CUU, which of the following can be another codon coding for leucine?
ACUA
BCCC
CUAA
DCCA
EAUG
An 8-year-old girl is brought to the emergency room for a 6-hour history of fever, sore throat, and difficulty swallowing. Physical examination shows pooling of oral secretions and inspiratory stridor. Lateral x-ray of the neck shows thickening of the epiglottis and aryepiglottic folds. Throat culture with chocolate agar shows small, gram-negative coccobacilli. The patient's brother is started on the recommended antibiotic for chemoprophylaxis. Which of the following is the primary mechanism of action of this drug?
AInhibition of the 50S ribosomal subunit
BInhibition of prokaryotic topoisomerase II
CInhibition of DNA-dependent RNA-polymerase
DInhibition of the 30S ribosomal subunit
EInhibition of peptidoglycan crosslinking
In translation, the wobble phenomenon is best illustrated by the fact that:
ACharged tRNA contains energy needed for peptide bonds to form
BThe last nucleotide provides specificity for the given amino acid
CA tRNA with the UUU anticodon can bind to either AAA or AAG codons
DThere are more amino acids than possible codons
EThe genetic code is preserved without mutations
+ 7 more in the PDF
Browse all chapters