5. The most common mutation in ACC cancer patients (occurring in 72% of all cases) involves the substitution of one amino acid for another in the protein. This type of change to the protein coding sequence is called a mutation 6. There are two other types of common point mutations that affect the coding sequence of various proteins. Briefly describe all three types of mutations in Table 3 and predict how the level of mRNA and protein might be affected (increased or decreased) by the mutation. Table 3 – The expression of genes implicated in ACC in six cancer patients and one healthy individual. Name of Mutation In what way does this mutation alter mRNA sequence? Could this mutation affect the level of functional protein in a cell? Would it increase or decrease the level protein in the cell? Why? Substitution of one amino acid for another in the protein Conclusion Sometimes mutations involve the deletion of large regions of genetic information. Other mutations affect gene expression by altering the DNA sequence of regulatory elements like promoter regions. Further analysis reveals that Lee has a mutation that affects mRNA splicing (removal of introns and splicing together of various exons), which occurs approximately 8% of the time in this condition. This mutation reduces the level of mature mRNA in his cells. This is why the level of the affected gene shows a lower expression level in Lee than it does in the healthy control patient.
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The most common type of mutation in cancer patients involves the substitution of one amino acid for another in the protein coding sequence. This type of mutation is called a missense mutation. Show more…
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Consider the RNA for eukaryotic protein genes. These RNA molecules are smaller (contain fewer bases) than they have in the cytoplasm. True False The genetic code defines how sequences of nucleotide triplets, called codons, specify which amino acid will be added next during protein synthesis; most importantly, the same code is used by all known taxa and highly conserved in viruses, bacteria, archaea, eukaryotes, and plants. The large molecular complex that associates with each intron and splices it is called a(n) spliceosome. Which phenomena is responsible for the ability of one gene to code for more than one form of a polypeptide? point mutations translocations alternate splicing patterns by the spliceosome cross-overs hybridization In most cases, which is NOT part of the sliceosome: Intron snRNA U6 5' splice site, A/C-AGGU-A/G-AGU Poly-A site; AAUAAA Exonic Splicing Enhancers (ESE) What is always the first amino acid incorporated at the N-terminus of a eukaryotic nascent (new) polypeptide chain? cysteine formyl-methionine (fMet) methionine polyA ATP Which eukaryotic translation factor is equivalent to prokaryotic EF-TU? elF4E TFIIH eEF-1A TATA IF2-GTP A nonsense mutation creates a stop codon. What is the result of a nonsense mutation? a frameshift a completely garbled sequence of amino acids a deficiency in one to the cells tRNA premature termination of mRNA (transcription) premature termination of protein synthesis
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5) Which of the following are true of the structure of proteins? a) Polypeptides consist of a series of amino acids, always arranged in a single, unbranched chain. b) The secondary structure of proteins is always in the form of two helices wound around each other. c) Only regulatory proteins have tertiary structure. d) Quaternary structure describes how multiple polypeptides combine to form a single unit. e) a and d f) b and c g) a, b, and c h) a, b, and d 6) The following mRNA codons encode the amino acid arginine: 5'-CGU 5'-CGC 5'-CGA 5'-CGG 5'-AGA 5'-AGG In light of this, which of the following are true? a) Due to "wobble", these codons could all bind to a single tRNA. b) Because only the first base of the codon can "wobble", there must be at least four tRNAs for arginine. c) Because only the third base of the codon can "wobble", there must be at least two tRNAs for arginine. d) The following are both possible anti-codons for an arginine tRNA: 5'-UCU, 5'-CCU e) both a and d f) both b and d g) both c and d 7) You are studying a mutant fruit fly that has a two-base-pair deletion in the third exon of its GADPH gene. Which of the following could be true of your mutant? a) Although one or two codons will be affected by this mutation, it will not cause a shift in the reading frame because more than one base pair was deleted. b) Since the mutation only occurs in an exon, it will be a neutral mutation. c) This mutation could be a spontaneous mutation caused by strand slippage during DNA replication d) Since the mutation is a deletion, it will not be passed on to any offspring the fly has. e) none of the above f) both a and b g) both b and c h) both c and d
20) Which of the following mutations is most likely to cause a phenotypic change? 21) Which small-scale mutation would most likely have a catastrophic effect on the functioning of a protein? 22) What is the effect of a nonsense mutation in a gene? 23) When translating secretory or membrane proteins, ribosomes are directed to the ER membrane by 24) Which of the following is a useful feature of introns in eukaryotic cells? 25) Which of the following does not occur in prokaryotic gene expression, but does in eukaryotic gene expression? 26) What is the source of the extra chromosome 21 in an individual with Down syndrome?
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