Exam 11: Chromosome Structure and Organelle Dna

How many base pairs per turn of the helix would MOST likely correspond to a negatively supercoiled DNA molecule?

The presence of more than one variation of DNA in the organelles of a single cell is called:

At the end of the nineteenth century, American bison were bred with domestic cattle in an attempt to rescue their declining populations. The resulting hybrids were bred with true bison. After many generations, animals that look like bison may still contain some ancestral cattle DNA. Ward et al. (Animal Conservation 2: 51-57, 1999) tested current bison herds for a mitochondrial DNA marker specific to cattle. Of the North American bison they tested, 5.2% had the cattle-specific mitochondrial DNA marker. Does this under- or overestimate the number of bison-cattle hybrids? Explain your answer.

If a bacterial chromosome were inserted into a eukaryotic cell, would it be stable and segregate like eukaryotic chromosomes do during mitosis and meiosis? (Select all that apply.)

Which of the following statements is NOT true?

DNA can be isolated from cells, and the different types of DNA from the cell can be separated by density gradient centrifugation. The following figures show the density gradient centrifugation profiles for DNA isolated from four different cell types: plant, animal, wild-type yeast with a plasmid, and petite yeast. - Which figure has the DNA profile that would most closely match DNA from a human cell?

How does the organization of the eukaryotic chromosome differ from the organization of a bacterial chromosome? Include in your answer (a) classes of DNA sequences, (b) special features of the chromosome, (c) organization of the genes within the chromosome, and (d) proteins that interact with chromosomal DNA.

How many complete rotations would MOST likely correspond to a negatively supercoiled DNA molecule that is 100 bp in length?

What is "satellite" DNA? Explain why satellite DNA anneals rapidly after it is denatured.

Which of the following amino acids has a positive charge that helps to hold the DNA in contact with the histones?

There are some genomes that have been reported to be positively coiled instead of negatively supercoiled, which is the status of most genomes that we have studied. The genomes that are positively supercoiled seem to belong to viruses and cells that exist at very high temperatures. Why might positive supercoiling be an advantage at high temperatures? (Select all that apply.)

Telomeres exist to help with the _____ of the ends of eukaryotic chromosomes.

A new Drosophila phenotype is investigated with a series of crosses. P (parental) organisms are true-breeding. The following is the first cross: Predict the F₂ results if the allele that causes the mutant phenotype is X-linked recessive. Then predict the results if the allele causing the mutant phenotype is mitochondrial.

Which of the following descriptions is NOT true of heterochromatin?

Describe the structure and packing of a bacterial chromosome.

How many different types of histones are found in the nucleosome that packages mitochondrial DNA?

Two haploid strains of petite yeast mutants are obtained independently. Each is crossed to a wild-type strain, and the resulting diploid is sporulated (goes through meiosis to produce haploid spores). Use the following results to explain the difference between the two strains and why the crosses give different results.

Assuming there are no heteroplasmic individuals but that people from different families have different DNA, how many different mitochondrial DNAs are there in the pedigree below?

Based on the pedigree below, which of the following statements correctly interpreted the pedigree with respect to X-linked dominant, X-linked recessive, Y-linked, mitochondrial, autosomal recessive, and autosomal dominant inheritance? (Select all that apply.)

The petite mutations in S. cerevisiae, was discovered by Boris Ephrussi and his colleagues in the late 1940s, result in much smaller colony size, reflecting the defect in the cellular growth rate (Figure 11.15). Most petite mutations are known to occur on mitochondrial DNA. Which of the following statements offer a logical explanation of the petite phenotype? Select all that apply. (Photo credit: [From Xin Jie Chen and G. Desmond Clark-Walker, Genetics 144: 1445-1454, Fig 1, 1996. © Genetics Society of America. Courtesy of Xin Jie Chen, Department of Biochemistry and Molecular Biology, SUNY Upstate Medical University.])