The use of nucleotide sequence data to measure genetic variabilityis complicated by the fact that the genes of many eukaryotesare complex in organization and contain 5' and 3' flankingregions as well as introns. Researchers have compared thenucleotide sequence of two cloned alleles of the y-globin gene from asingle individual and found a variation of 1 percent. Those differencesinclude 13 substitutions of one nucleotide for anotherand three short DNA segments that have been inserted in oneallele or deleted in the other. None of the changes takes placein the gene’s exons (coding regions). Why do you think this isso, and should it change our concept of genetic variation?

In Meselson and Radding modified Holliday model, following branch migration, what are the possible number of heteroduplex regions that can occur? 3 4

A woman has had five children with two different men. This groupof seven individuals is analyzed with regard to three differentSTSs: STS-1 is 146 bp and 122 bp; STS-2 is 102 bp and 88 bp;and STS-3 is 188 bp and 204 bp. The mother is homozygous forall three STSs: STS-1 = 122, STS-2 = 88, and STS-3 = 188. Father1 is homozygous for STS-1 = 122 and STS-2 = 102, and heterozygousfor STS-3 = 188 and 204. Father 2 is heterozygous forSTS-1 = 122 and 146, STS-2 = 88 and 102, and homozygous forSTS-3 = 204. The five children show the following results:

If the bandicoot genome is 3.62 x 109 base pairs, and the "highly repetitive DNA" fraction is composed entirely of copies of sequence 5'TGCGTGTGTGC3' and its complement, how many copies of this sequence are present in the bandicoot genome?

Using the conventions of Figure 4-15, draw parents andprogeny classes from a crossP M′′′/p M′ × p M′/p M′′′′

The HbβS(sickle-cell) allele of the human β-globingene changes the sixth amino acid in the β-globinchain from glutamic acid to valine. In HbβC, the sixthamino acid in β-globin is changed from glutamic acidto lysine. What would be the order of these two mutations within the map of the β-globin gene?

By conducting conjugation experiments between Hfr and recipientstrains, Wollman and Jacob mapped the order of many bacterialgenes. Throughout the course of their studies, they identified severaldifferent Hfr strains in which the F-factor DNA had been integratedat different places along the bacterial chromosome. A sample of theirexperimental results is shown in the table:Draw a map that shows the order of genes and the locations ofthe origins of transfer among these different Hfr strains?

The completely synthetic yeast chromosome Syn IIIcontains a loxP site in the 3′ UTR of every gene thatis potentially nonessential to yeast survival. As youwill recall from Chapter 6, loxP sites are targets ofsite-specific recombination. The researchers who constructed Syn III included these loxP sites as a way to“scramble” the chromosome, meaning that parts ofthe chromosome could easily be deleted or rearranged.The goal of these investigations is to drive the evolution of Syn III so as to define a minimal genome thatcan support the life of this organism. Outline the experiment the researchers would do to scramble Syn IIIin order to define a minimal genome.

A double mutant produced by uneven crossing-over contains two single nucleotide mutations that result in frame shifts and are separated by about 20 base pairs.  The first is an insertion, while the second is a deletion.  The amino acid sequences of the wildtype and mutant polypeptide in this region of the protein are as follows: Wildtype: Lys – Lys – Tyr – His – Gln – Trp – Thr – Cys – AsnDouble Mutant: Lys – Gln – Ile – Pro – Pro – Val – Asp – Met – Asn a) What are the original and double mutant mRNA sequences.  You may find it useful to use the conventional symbols Y for pyrimidine, R for purine, N for any nucleotide, and H for A,C, or T.   2. b) Which nucleotide was inserted?   3. c) Which nucleotide was deleted?

What is a contig?