MikeJ

Hey all! I've been struggling with this question for almost a week now, and I seem to misunderstand some principles leading to a solution. I hope anyone could help out! Here it goes: Consider the following pedigree, showing a disease in humans. The DNA sequence causing the disease is known. A group of researchers has prepared a probe for the entire mutant DNA sequence, used to yield the following southern blot. Assume that the probe can identify all possible alleles for the mutant gene (A/B/C). Note that the thickness of the band is meaningless. A) Predict the hereditary mechanism for the following disease. B) Both parents have had two more children; a boy and a girl. Southern Blot procedure for both has shown that the male showed a band for B, and the female showed a band for B as well as for C. Determine the phenotype of the two children. C) Can you find any evidence for crossovers in this pedigree? If so, where? A) The hereditary mechanism is probably X-linked recessive. Now, what I don't get here: Male I-2 has allele A, coding for the disease. Male II-1 has allele B, not coding for the disease, while Male II-3 has also allele B, coding for the disease. If so - what is the allele coding for the disease? Is it A? Is it B? If this was the crossover, why aren't we observing a band also for the recombinant allele? It looks as if something is missing here, or I'm just not getting it. Does this make any sense to anyone here? It'd be highly appreciated! Thanks!

I'd say what I'm struggling with the most is figuring out what X could stand for. The mutations in Sequence #2 are simple substitution mutations coding for tyr and met. In sequence #3 there must be 3 insertion mutations that will cause an addition of an extra codon, coding for an additional amino acid. But there could be so many possibilities and I can't find a simple way to answer this question, not stating around 100 options. The Sense DNA strand is the DNA Strand who's nucleotide sequence corresponds directly to the sequence of an RNA transcript which is translated. The sense DNA for sequence 3 would be: So i'm assuming there were 3 insertion mutations, roundabout phe-lys. But again, it could be anything and there are many possibilities. Is there any smart way to get around this? – Lys – – Phe – – Ile – – Leu – – Cys – Amino Acid Sequence AAA AAG UUU UUC AUU AUC AUA UUA UUG CUU CUC CUA CUG UGU UGC RNA Sequence – AAA – – TTT– – ATT – – TTA – – TGT – Sense DNA Sequence

Hello all, I've been trying to figure this question out for a week now, but can't seem to be reaching a logical answer. I'd very much appreciate if anyone could help me see how this prolem should be solved. Here it goes: Consider the following wild-type amino acid sequence in bacteria: N-Ser-Leu-Ile-Leu-Ser-C A researcher has induced various mutations in the bacteria, and has isolated two species containing a mutant amino acid sequence. Sequence #2: N-Tyr-Leu-Met-Leu-Ser-C Sequence #3: N-Cys-Leu-Ile-Phe-Lys-X-C 1. State the Sense-DNA sequence for each of the above amino-acid sequences. 2. What Amino Acid could be "X" in sequence #3? State all possible answers. Thanks A lot!!!