Exam 16: Forward Genetics and Recombinant DNA Technology

Suppose a scientist wants to identify a gene in a particular plant species by transposon tagging,but he is initially stumped because he finds no active transposons.He hypothesizes,however,that he can introduce a transposon from another plant species.Why might this be possible?

Which of the following vectors would be most efficient to use to amplify fragments ~300 kb in length?

Among the attributes of model organisms,which of the following characteristics of C.elegans makes it useful for mutagenesis?

Before Muller's discovery that radiation induces mutation,scientists had to work on mutations that were found solely by phenotype differences in natural populations.Which of the features of Drosophila made it a fortuitous choice for Morgan and his colleagues?

Some restriction enzymes cut at specific and unambiguous sequences (e.g.,NotI at GCGGCCGC).As such,the distance between two such sites in a large random DNA sequence is 4⁸.However,the sequence recognized by XhoII is said to be ambiguous (Pu-GATC-Py,where Pu = any purine and Py any pyrimidine).What,therefore,is the expected distance between two XhoII sites in a large random sequence?

Current sequencing technologies have major advantages over the dideoxy method because they produce more sequence in less time and at less cost.Which of the following would provide further advantage?

Which approach for sequencing large DNA molecules uses fragmentation that produces random but overlapping pieces?

In 1978,Arber,Smith,and Nathans won the Nobel Prize in Physiology and Medicine for work with restriction enzymes.Which of the following can still be performed without using these enzymes?

In the construction of a YAC library,each chromosome has the advantage of being able to hold very long DNA sequences.However,besides selectable marker(s)the YAC vector must minimally include which of the following?

In a simple restriction mapping study,a sequence was cut by BamHI into one large and one small fragment.Cutting the same sequence with XhoI also results in two fragments.What can be done next to begin to map these sites?

How can blunt-ended DNA fragments be altered to allow them to be incorporated into a plasmid with sticky ends?

In positional cloning,the researcher begins with a phenotype.To move toward identification of its DNA sequence,she must begin with what step?

What kind of analysis is needed to determine whether two mutations are in the same gene or in different genes?

Why do we so frequently use mutant alleles to determine structure and/or function of the wild type?

In forensics,the laws in the United States and elsewhere allow the establishment of databases of PCR amplification of short tandem repeats (STRs)of the Y chromosome.Which of these statements would provide an appropriate basis for making such databases divided by ethnicity?

How can you use the known human cDNA gene sequence for cytC that you already have in an experiment(s)to identify and compare the sequences from other vertebrates?

If a mutagenesis screen provides some number (e.g.,24)of alleles shown by complementation analysis to be in the same gene,which of the following is true?

Why is only a fraction of an organism's genes represented in any cDNA library?

Specific sequences in the lambda genome that interact with coat proteins to package genomes into phage particles are known as ________ sites.

In selecting recombinant bacteria,cells are chosen that are resistant to a specific antibiotic.How are the bacteria made resistant?