Are the 5′ untranslated regions (5′ UTR) of eukaryotic mRNAs encoded by sequences in the promoter, exon, or intron of the gene? Explain your answer.

Introns are often very large and the cell has devoted mechanisms of eliminating them once they are excised from the pre-mRNA. Following intron excision, what specific ribonucleolytic enzymes or complexes contribute to eliminating the intron RNA immediately after it is excised from the pre-mRNA? Briefly describe the role of each step/enzyme and how it affects its RNA substrate

A common feature of many eukaryotic mRNAs is the presence of a rather long 3′ UTR, which often contains consensus sequences. Creatine kinase B (CK-B) is an important enzyme in cellular metabolism. Certain cells—termed U937D cells—have lots of CK-B mRNA, but no CK-B enzyme is present. In these cells, the 5′ end of the CK-B mRNA is bound to ribosomes, but the mRNA is apparently not translated. Something inhibits the translation of the CK-B mRNA in these cells. Researchers introduced numerous short segments of RNA containing only 3′ UTR sequences into U937D cells. As a result, the U937D cells began to synthesize the CK-B enzyme, but the total amount of CK-B mRNA did not increase. The introduction of short segments of other RNA sequences did not stimulate the synthesis of CK-B; only the 3′ UTR sequences turned on the translation of the enzyme. On the basis of these results, propose a mechanism for the inhibition of CK-B translation in the U937D cells. Explain how the introduction of short…

Which of the following mutations in the protein-coding region of a gene is more likely to lead to complete loss of function of the encoded protein: an insertion of six nucleotides or a deletion of two nucleotides? Briefly explain your answer.

Before the Genetic Code was solved, scientists predicted that mRNA codons would need to be a minimum of three bases long (ex. AAA, not AA or A) to code for a single amino acid. What was the reason they predicted this?

Define both transcription and translation. In addition, describe the role(s) of each of the following in the processes of gene expression and protein synthesis:  DNA, mRNA, tRNA, rRNA, ribosome(s), RNA polymerase, codon, anticodon, amino acid(s) and polypeptide(s). Be detailed in your answer.

Indicate the amino acid sequence of the protein encoded by the following mRNA molecule.  Use the genetic code table and assume that the very first “AUG” the ribosome encounters will serve as the start codon and specify methionine. 5’-AAUUCAUGCCCAAAUUUGGGGCACGAAGCUUCUUAGGCUAGUCCUAAAAAA-3’

For each of the following, identify whether that sequence or feature of a typical protein-coding gene would be recognizable in the specified molecule in a typical prokaryotic cell. 5' UTR in DNA? 5' UTR in mRNA? Shine-Dalgarno in DNA? Shine-Dalgarno in polypeptide? Promoter in RNA? Promoter in polypeptide sequence? Stop codon in mRNA? Stop codon in the polypeptide sequence? [Choose ] [Choose ] [Choose ] [Choose ] [Choose ] [Choose ] [Choose ] [Choose ] > <