When a eukaryotic gene is cut out of genomic DNA, geneticists have discovered that enabling the strands to hydrogen bond allows them to hybridize one of the gene's strands to the mRNA for that gene. How can you tell whether this gene undergoes alternative splicing by comparing the mRNAs that result?

Match the term with its definition comparing genomic DNA, mRNA, and proteins. You may only use each option ONCE. where transcription starts. where translation ends a chemical group that indicates the first nucleotide that was added to the mRNA a chemical group that indicates the first amino acid that was added to the polypeptide a DNA sequence that is neither transcribed nor translated a non-protein coding region upstream of the start codon in the mRNA promoter complimentary base-pairs with the codon amino-terminus a DNA sequence that is transcribed, but not intron translated [Choose ] stop codon +1 site tRNA 5-prime UTR start codon exon 5-prime triphosphate promoter amino-terminus 5-prime triphosphate stop codon

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…