Mutations are pondered.

A student in a molecular genetics lab is using the SSCP technique to analyze DNA from breast cancer tumours, and has identified five different shifts in fragments of the BARD1 gene. (BARD1 [genbank accession number NM_000465] is a tumour suppressor gene, mutations in which are associated with breast cancer.) Partial sequences from those shifted bands are given below; for each, describe what type of mutation has occurred (e.g.. transition, etc.), the molecular consequences of the mutations (i.e. what happens to the protein), and whether they are likely to be benign polymorphisms or deleterious mutations. (N.B. Sequences are 5’ -> 3’ for the coding strand, given in triplets, numbers correspon... click for more

It's regarding genotypes and linkages.

A hairy-winged (h) Drosophila female is mated with a yellow-bodied (y), white-eyed (w) male. The F1 are all normal. The F1 progeny are then crossed and the F2 that emerge are Females: Wild-type 757 Hairy 243 Males: Wild-type 390 Hairy 130 Yellow 4 White 3 Hairy, yellow 1 Hairy, white 2 Yellow, white 360 Hairy, yellow, white110 Give genotypes of the parents and F1 and note any linkage relations and map distances. Ans: I have got h++/h++ for the female parent mating with +yw/+yw male. The F1 genotype that I have got is h++/+yw, which would all be normal. I dont know i... click for more

Likages are explored.

In Aspergillus, the genes y (yellow), os (osmotic), c (colonial), leu (leucine-requiring), and a (aconidial) are located on the long arm of chromosome 3. A diploid was made between a haploid wild type and a haploid of genotype y os c leu a. From the green diploid, yellow diploid sectors appeared. When these were sampled and tested, the following was found: 56%were yellow, osmotic, aconidial, and leucine-requiring 40%were yellow, osmotic, colonial, aconidial, and leucine-requiring 4%were yellow, aconidial, and leucine-requiring (a) What is the origin of the three types of yellow sectors? (Diagram it on chromosomes) (b) What is the order and relative map distances of the five loci? Help... click for more

It's regarding mutations

a student in a molecular genetics lab is using the SSCP technique to analyze DNA from breast cancer tumours and has identified five different shifts in fragments of the BARD1 gene. (BARD1 [genbank accession number NM_000465] is a tumour suppressor gene, mutations in which are associated with breast cancer.) Partial sequences from those shifted bands are given below; for each, describe what type of mutation has occurred (e.g.. transition, etc.), the molecular consequences of the mutations (i.e. what happens to the protein), and whether they are likely to be benign polymorphisms or deleterious mutations. (N.B. Sequences are 5’ -> 3’ for the coding strand, given in triplets, numbe... click for more

Drosophilla crosses are calculated.

In a lab strain of Drosophila, cinnabar (cn) and brown (bw) are recessive eye colour mutations known to be 41 m.u. apart on chromosome 2. When similar mutant alleles were induced in a strain from nature, the same linkage of cn and bw was observed. However, when a wild-type strain from nature was crossed with a cn bw/cn bw lab strain to create the genotype + +/cn bw, and females of this type were test-crossed to cn bw/cn bw males from the lab strain, the following phenotypic proportions were observed in the progeny: + + 25,200 cn bw 21,009 cn + 11 + bw 36 (a) What is unexpected about these results? (b) What is the most likely explanation? (Draw a diagram) (c) On th... click for more