Chapter 21

13) Which of the following seems to be the known upper and lower size limits of genomes? A) 1—2900 Mb (million base pairs) B) 1,500—40,000 Mb C) 1—580,000 Mb D) 100—120,000 Mb E) 100—200,000 Mb

C) 1—580,000 Mb

2) What is the difference between a linkage map and a physical map? A) For a linkage map, markers are spaced by recombination frequency, whereas for a physical map they are spaced by numbers of base pairs (bp). B) For a physical map, the ATCG order and sequence must be achieved, but not for the linkage map. C) For a linkage map, it is shown how each gene is linked to every other gene.

A) For a linkage map, markers are spaced by recombination frequency, whereas for a physical map they are spaced by numbers of base pairs (bp).

30) Homeotic genes contain a homeobox sequence that is highly conserved among very diverse species. The homeobox is the code for that domain of a protein that binds to DNA in a regulatory developmental process. Which of the following would you then expect? A) That homeotic genes are selectively expressed over developmental time. B) That a homeobox containing gene has to be a developmental regulator. C) That homeoboxes cannot be expressed in non-homeotic genes. D) That all organisms must have homeotic genes. E) That all organisms must have homeobox containing genes.

A) That homeotic genes are selectively expressed over developmental time.

25) In comparing the genomes of humans and those of other higher primates, it is seen that humans have a large metacentric pair we call chromosome #2 among our 46 chromosomes, while the other primates of this group have 48 chromosomes and any pair like the human #2 pair is not present; instead the primate groups each have two pairs of midsize acrocentric chromosomes. What is the most likely explanation? A) The ancestral organism had 48 chromosomes and at some point a centric fusion event occurred and provided some selective advantage. B) The ancestral organism had 46 chromosomes, but primates evolved when one of the pairs broke in half. C) At some point in evolution, human ancestors and primate ancestors were able to mate and produce fertile offspring, making a new species. D) Chromosome breakage results in additional centromeres being made in order for meiosis to proceed successfully. E) Transposable elements transferred significantly large segments of the chromosomes to new locations.

A) The ancestral organism had 48 chromosomes and at some point a centric fusion event occurred and provided some selective advantage.

20) What is it about short tandem repeat DNA that makes it useful for DNA fingerprinting? A) The number of repeats varies widely from person to person or animal to animal. B) The sequence of DNA that is repeated varies significantly from individual to individual. C) The sequence variation is acted upon differently by natural selection in different environments. D) Every racial and ethnic group has inherited different short tandem repeats.

A) The number of repeats varies widely from person to person or animal to animal

8) Bioinformatics can be used to scan sequences for probable genes looking for start and stop sites for transcription and for translation, for probable splice sites, and for sequences known to be found in other known genes. Such sequences containing these elements are called A) expressed sequence tags. B) cDNA. C) multigene families. D) proteomes. E) short tandem repeats.

A) expressed sequence tags.

11) Why is it unwise to try to relate an organism's complexity with its size or number of cells? A) A very large organism may be composed of very few cells or very few cell types. B) A single-celled organism, such as a bacterium or a protist, still has to conduct all the complex life functions of a large multicellular organism. C) A single-celled organism that is also eukaryotic, such as a yeast, still reproduces mitotically. D) A simple organism can have a much larger genome. E) A complex organism can have a very small and simple genome.

B) A single-celled organism, such as a bacterium or a protist, still has to conduct all the complex life functions of a large multicellular organism.

17) Barbara McClintock, famous for discovering that genes could move within genomes, had her meticulous work ignored for nearly 4 decades, but eventually won the Nobel Prize. Why was her work so distrusted? A) The work of women scientists was still not allowed to be published. B) Geneticists did not want to lose their cherished notions of DNA stability. C) There were too many alternative explanations for transposition. D) She allowed no one else to duplicate her work. E) She worked only with maize, which was considered "merely" a plant.

B) Geneticists did not want to lose their cherished notions of DNA stability.

26) Unequal crossing over during Prophase I can result in one sister chromosome with a deletion and another with a duplication. A mutated form of hemoglobin, known as hemoglobin Lepore, is known in the human population. Hemoglobin Lepore has a deleted set of amino acids. If it was caused by unequal crossing over, what would be an expected consequence? A) If it is still maintained in the human population, hemoglobin Lepore must be selected for in evolution. B) There should also be persons born with, if not living long lives with, an anti-Lepore mutation or duplication. C) Each of the genes in the hemoglobin gene family must show the same deletion.

B) There should also be persons born with, if not living long lives with, an anti-Lepore mutation or duplication.

6) What is bioinformatics? A) a technique using 3D images of genes in order to predict how and when they will be expressed B) a method that uses very large national and international databases to access and work with sequence information C) a software program available from NIH to design genes D) a series of search programs that allow a student to identify who in the world is trying to sequence a given species E) a procedure that uses software to order DNA sequences in a variety of comparable ways

B) a method that uses very large national and international databases to access and work with sequence information

29) What does the field often called "evo-devo" study? A) whether or not development is an evolutionary process B) how developmental processes have evolved C) whether or not all animals have developmental regulation D) whether the pattern of human development evolved early or late E) whether or not there are specific genes controlling development

B) how developmental processes have evolved

1) For mapping studies of genomes, most of which were far along before 2000, the 3-stage method was often used. Which is the usual order in which the stages were performed, assuming some overlap of the three? A) genetic map, sequencing of fragments, physical map B) linkage map, physical map, sequencing of fragments C) sequencing of entire genome, physical map, genetic map D) cytogenetic linkage, sequencing, physical map E) physical map, linkage map, sequencing

B) linkage map, physical map, sequencing of fragments

7) What is proteomics? A) the linkage of each gene to a particular protein B) the study of the full protein set encoded by a genome C) the totality of the functional possibilities of a single protein D) the study of how amino acids are ordered in a protein

B) the study of the full protein set encoded by a genome

21) Alu elements account for about 10% of the human genome. What does this mean? A) Alu elements cannot be transcribed into RNA. B) Alu elements evolved in very ancient times, before mammalian radiation. C) Alu elements represent the result of transposition. D) No Alu elements are found within individual genes. E) Alu elements are cDNA and therefore related to retrotransposons.

C) Alu elements represent the result of transposition.

15) Which of the following is a representation of gene density? A) Humans have 2,900 Mb per genome. B) C. elegans has ~20,000 genes. C) Humans have ~25,000 genes in 2,900 Mb. D) Humans have 27,000 bp in introns. E) Fritillaria has a genome 40 times the size of a human.

C) Humans have ~25,000 genes in 2,900 Mb.

28) In order to determine the probable function of a particular sequence of DNA in humans, what might be the most reasonable approach? A) Prepare a knockout mouse without a copy of this sequence and examine the mouse phenotype. B) Genetically engineer a mouse with a copy of this sequence and examine its phenotype. C) Look for a reasonably identical sequence in another species, prepare a knockout of this sequence in that species and look for the consequences. D) Prepare a genetically engineered bacterial culture with the sequence inserted and assess which new protein is synthesized. E) Mate two individuals heterozygous for the normal and mutated sequences.

C) Look for a reasonably identical sequence in another species, prepare a knockout of this sequence in that species and look for the consequences.

14) If humans have 2,900 Mb, a specific member of the lily family has 120,000 Mb, and a yeast has ~13 Mb, why can't this data allow us to order their evolutionary significance? A) Size matters less than gene density. B) Size does not compare to gene density. C) Size does not vary with gene complexity. D) Size is mostly due to "junk" DNA. E) Size is comparable only within phyla.

C) Size does not vary with gene complexity.

9) Why is it preferable to use large computers and databases in searching for individual genes, rather than testing each sequence for possible function? A) Testing for function would require too many cells. B) Testing for function would require knowing the species, its life stage, and its phylogeny. C) Testing for function would require knowing where a particular gene starts and ends and how it is regulated. D) Use of computer databases is intellectually less rigorous. E) The computer data can be sent to more labs.

C) Testing for function would require knowing where a particular gene starts and ends and how it is regulated.

27) When does exon shuffling occur? A) during splicing of DNA B) during mitotic recombination C) as an alternative splicing pattern in post-transcriptional processing D) as an alternative cleavage or modification post-translationally E) as the result of faulty DNA repair

C) as an alternative splicing pattern in post-transcriptional processing

10) A microarray known as a GeneChip, with most now known human protein coding sequences, has recently been developed to aid in the study of human cancer by first comparing two_three subsets of cancer subtypes. What kind of information might be gleaned from this GeneChip to aid in cancer prevention? A) information about whether or not a patient has this type of cancer prior to treatment. B) evidence that might suggest how best to treat a person's cancer with chemotherapy. C) data that could alert patients to what kind of cancer they were likely to acquire. D) information about which parent might have provided a patient with cancer-causing genes. E) information on cancer epidemiology in the U.S. or elsewhere.

C) data that could alert patients to what kind of cancer they were likely to acquire.

3) How is a physical map of the genome of an organism achieved? A) using recombination frequency B) using very high-powered microscopy C) using restriction enzyme cutting sites D) using sequencing of nucleotides E) using DNA fingerprinting via electrophoresis

C) using restriction enzyme cutting sites

18) Which of the following is a major distinction between a transposon and a retrotransposon? A) A transposon always leaves a copy of itself at its original position and a retrotransposon does not. B) A retrotransposon always uses the copy-paste mechanism, while a transposon uses cut and paste mechanism. C) A transposon is related to a virus and a retrotransposon is not. D) A transposon moves via a DNA intermediate and a retrotransposon via an RNA intermediate. E) The positioning of a transposon copy is transient while that of a retrotransposon is permanent.

D) A transposon moves via a DNA intermediate and a retrotransposon via an RNA intermediate.

16) Why might the cricket genome have 11 times as many base pairs than that of Drosophila melanogaster? A) The two insect species evolved at very different geologic eras. B) Crickets have higher gene density. C) Drosophila are more complex organisms. D) Crickets must have more non-coding DNA. E) Crickets must make many more proteins.

D) Crickets must have more non-coding DNA.

Multigene families include two or more nearly identical genes or genes sharing nearly identical sequences. A classical example is the set of genes for globin molecules, including genes on human chromosomes 11 and 16. 22) How might identical and obviously duplicated gene sequences have gotten from one chromosome to another? A) by normal meiotic recombination B) by normal mitotic recombination between sister chromatids C) by transcription followed by recombination D) by chromosomal translocation E) by deletion followed by insertion

D) by chromosomal translocation

4) Which of the following most correctly describes a shotgun technique for sequencing a genome? A) genetic mapping followed immediately by sequencing B) physical mapping followed immediately by sequencing C) cloning large genome fragments into very large vectors such as YACs, followed by sequencing D) cloning several sizes of fragments into various size vectors, ordering the clones, and then sequencing them E) cloning the whole genome directly, from one end to the other

D) cloning several sizes of fragments into various size vectors, ordering the clones, and then sequencing them

12) Fragments of DNA have been extracted from the remnants of extinct wooly mammoths, amplified, and sequenced. These can now be used to A) introduce into relatives, such as elephants, certain mammoth traits. B) clone live wooly mammoths. C) study the relationships among wooly mammoths and other wool-producers. D) understand the evolutionary relationships among members of related taxa. E) appreciate the reasons why mammoths went extinct

D) understand the evolutionary relationships among members of related taxa.

19) What is the most probable explanation for the continued presence of pseudogenes in a genome such as our own? A) They are genes that had a function at one time, but that have lost their function because they have been translocated to a new location. B) They are genes that have accumulated mutations to such a degree that they would code for different functional products if activated. C) They are duplicates or near duplicates of functional genes but cannot function because they would provide inappropriate dosage of protein products. D) They are genes with significant inverted sequences. E) They are genes that are not expressed, even though they have nearly identical sequences to expressed genes.

E) They are genes that are not expressed, even though they have nearly identical sequences to expressed genes.

23) Several of the different globin genes are expressed in humans, but at different times in development. What mechanism could allow for this? A) exon shuffling B) intron activation C) pseudogene activation D) differential translation of mRNAs E) differential gene regulation over time

E) differential gene regulation over time

5) The biggest problem with the shotgun technique is its tendency to underestimate the size of the genome. Which of the following might best account for this? A) skipping some of the clones to be sequenced B) missing some of the overlapping regions of the clones C) counting some of the overlapping regions of the clones twice D) having some of the clones die during the experiment and therefore not be represented E) missing some duplicated sequences

E) missing some duplicated sequences

24) What is it that can be duplicated in a genome? A) DNA sequences above a minimum size only B) DNA sequences below a minimal size only C) entire chromosomes only D) entire sets of chromosomes only E) sequences, chromosomes, or sets of chromosomes

E) sequences, chromosomes, or sets of chromosomes