pliced Tbx5 DIE3UIUN mRNA are greatly reduced. What kind of mutation is most lik
ID: 252446 • Letter: P
Question
pliced Tbx5 DIE3UIUN mRNA are greatly reduced. What kind of mutation is most likely mature, 8f properly accounts for this phenotype? (3 pts) Question 6 (total of 15 points) Congenital heart defects are present in 1-2% of newborns and cause a significant number of stillbirths. They are also a major cause of heart disease in adults. Many congenital heart defects are due to mutations in genes for transcription factors that control expression of genes that are required for normal heart development. For example, >30 different mutations have been identified in transcription factor Tbx5 in patients with congenital heart defects. Tbx5 must bind to another transcription factor called Nkx2-5 for its gene to become fully- expressed As a scientist, you can isolate developing cardiac cells with different Tbx5 mutations and study the molecular defects caused by its mutations in the laboratory. 6a. In one mutant cell line, you find that mature Tbx5 mRNA is present at its full- length, normal expression level. However, full-length Tbx5 protein cannot be detected. What kind of mutation is most likely accounts for this phenotype? (3 pt). Explain your answer in detail (eg. why A and why not B etc) (6 pts) [note: read and think carefully!] A. a mutation that blocks binding of Tbx5 to Nkx2-5 B. a mutation that causes a splicing defect C. a mutation that disrupts the normal folding of Tbx5 protein D. a mutation that introduces a premature stop codonExplanation / Answer
6a. ans is D- a mutation that introduces a premature stop codon. This is because a premature stop codon would result in a truncated protein and not a full length protein. This would explain the absence of a full length Tbx5 protein.
The answer cannot be A. a mutation that blocks binding of Tbx5 to Nkx2-5 because first of all you need a full length Tbx5 protein in order to bind Nkx2-5. Since there is no full length Tbx5 in the first place this cannot be the reason.
The answer cannot be B. a mutation that causes a splicing defect because the full length mature Tbx5 mRNA is present. A mature mRNA is formed after splicing.
The answer cannot be C. a mutation that disrupts the normal folding of Tbx5 protein because even if it didnt fold properly the protein should still be detected which is not the case here.
Related Questions
Navigate
Integrity-first tutoring: explanations and feedback only — we do not complete graded work. Learn more.