Predict what will happen when a cell growing in the presence of lactose contains a deletion of one nucleotide early in the Z gene and early in the A gene.

In eukaryotes there is not a consistent relationship between the length of the coding sequence of a gene and the length of the mature mRNA it encodes, even though one nucleotide in DNA = one nucleotide in pre-mRNA or primary transcript.  Explain why this is so.

some eukaryotic mRNAs have internal ribosome binding sites, where ribosomes can bind without first attaching to the 5′ cap. Yet all eukaryotic mRNAs are capped, and cap-dependent translation is highly efficient. What might be the advantage of having internal ribosome binding sites if the cap permits the initiation of translation and all eukaryotic mRNAs are capped?

Let's say there is an eukaryotic gene that has five exons and 4 introns. If the GU sequence at the 5' splice site of the third intron is deleted, describe how this is going to affect the expression of this gene. draw the mature mRNA too.

Briefly discuss (referring to the images provided) why mutant 2 fails to produce functional protein. Note that none of the mRNA transcribed from this gene is of the expected size; some of the mRNA molecules produced are 223 nucleotides shorter than expected, whilst others are 47 nucleotides longer than expected.

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.

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’