based on your knowledge of transcription and translation, what could be the unde

Question

based on your knowledge of transcription and translation, what could be the underlying molecular defect if both mRNA and protein levels for a particular gene are higher than normal? think of several alternative explanations (possible moelcular defects if mRNA levels and protein levels are higher than normal).

based on your knowledge of transcription and translation, what could be the underlying molecular defect if mRNA levels are normal but protein levesl for a particular gene are high? think of several alternative explanations (possible molecular defects if mRNA levels are normal but protein levels are higher than normal)

Explanation / Answer

At molecular level there are two main types of point mutational changes: base substitutions and base additions ordeletions. single-base additions or deletions have consequences on polypeptide sequence that extend far beyond the site of the mutation itself. Because the sequence of mRNA is “read” by the translational apparatus in groups of three base pairs (codons), the addition or deletion of a single base pair of DNA will change the reading frame starting from the location of the addition or deletion and extending through to the carboxy terminal of the protein. Hence, these lesions are called frameshift mutations. These mutations cause the entire amino acid sequence translationally downstream of the mutant site to bear no relation to the original amino acid sequence. Thus, frameshift mutations typically exhibit complete loss of normal protein structure and function.

A some situtations that occur in regulatory and other noncoding sequences. Those parts of a gene that are not protein coding contain a variety of crucial functional sites. At the DNA level, there are sites to which specifictranscription-regulating proteins must bind. At the RNA level, there are also important functional sequences such as the ribosome-binding sites of bacterial mRNAs and the self-ligating sites for intron excision in eukaryote mRNAs.

The ramifications of mutations in parts of a gene other that the polypeptide-coding segments are much harder to predict. In general, the functional consequences of any point mutation (substitution or addition or deletion) in such a region depend on its location and on whether it disrupts a functional site. Mutations that disrupt these sites have the potential to change the expression pattern of a gene in terms of the amount of product expressed at a certain time or in response to certain environmental cues or in certain tissues.

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