Indicate the answer choice that best completes the statement or answers the ques
ID: 100864 • Letter: I
Question
Indicate the answer choice that best completes the statement or answers the question. It was recently discovered that AUG is not always the start codon in which of the following systems? a. viruses b. mammalian immune system proteins c. mitochondria d. all of these The final form of mRNA in eukaryotes has all these features, except: a. There will be a special nucleotide cap on the 5' end of the mRNA. b. There is usually a poly A tail on the 3' end of the mRNA. c. The mature, active mRNA contains introns. d. Only a single protein is made from any mature mRNA molecule. e. All of these are true. Inosine or hypoxanthine can wobble with all the following bases, except: a. A b. C c. T d. U e. Inosine can wobble with all of these bases. In the wobble phenomenon, the base that wobbles is found in a. the tRNA. b. the mRNA c. either the tRNA or the mRNA. What type of assay using tRNAs and ribosomes enabled complete determination of the genetic code? a. filter binding assays b. high performance chromatography c. electrophoresis d. density gradient centrifugation Ribosomal frameshifting in Influenza Virus A is caused by the fact that a. the virus has a modified genetic code b. the virus attacks the mRNA c. the ribosome reaches a rare arginine codon and stalls out d. none of theseExplanation / Answer
Q.1. It was recently discovered that AUG is not always the start codon in which of the following systems
Ans: All of these .
AUG is not always a start codon mammalian immune system uses CUG as start codon.
cellular and viral mRNAs are known to use non-AUG codons, such as AUU, CUG, and GUG,
Mitochondrial genomes (and prokaryotes) also uses alternative start codon such as (AUA and AUU in humans and mainly GUG and UUG in prokaryotes).
Q.2. The final form of mRNA in eucaryotes has all these features excepts
Ans: The mature , active mRNA contains introns.
Introns are nucleotide sequence present within a gene and needs to be removed before translation. These introns are removed by RNA splicing during process of maturation in order to make final form of mRNA to ready for translation process.
Q.3. Inosine or hypoxanthine can wobble with all the following bases, except
Ans.Thymine (T)
Wobble is a base pairing happens in RNA molecules not in DNA. So thymine does not undergoes wobbling.
Q.4. In the wobble phenomenon, the base that wobbles is found in
Ans. tRNA
As our system has less or limited amount of tRNA so evolutionally allows wobbling for broad specificity.
Q.5.What type of assay using tRNA and ribosomes enabled complete determination of the gentic code
Ans. Filter binding assays
The simplest and very accurate method for detecting RNA- protein interaction is the filter based assay. It measures affinity between two molecules and also determines the binding constant and clearly shows how much interaction happens between RNA and ribosome.
Q.6. Ribosomal frameshifting in Influenza Virus A is caused by the fact that
Ans. The has Modified genetic code
Novel gene PA-X in influenza virus modifies the reading frame shift.