Deck 8: Digital Analysis of Genomes

Question 1

Karyotypes generally remain constant within a species because

A) rearrangements occur frequently.
B) changes in chromosome number occur infrequently.
C) genetic instabilities produced by genomic changes usually are at a selective disadvantage.
D) genetic imbalances are often at a selective advantage.
E) DNA replication has evolved to handle only a specific number of chromosomes.

Answer 1

C

Question 2

Of the following segregation patterns,which one is most likely to result in a normal zygote?

A) alternate
B) adjacent-1
C) adjacent-2
D) nondisjunction
E) triploid

Answer 2

A

Question 3

Despite selection against chromosomal variations

A) related species almost always have the same karyotype.
B) total DNA content varies widely between individuals within the same species.
C) closely related species diverge by many chromosomal rearrangements.
D) distantly related species diverge by only a few chromosomal rearrangements.
E) related species almost always have a different karyotype.

Answer 3

E

Question 4

The condition of semisterility is most closely associated with

A) chromosomal duplications.
B) pericentric inversions.
C) translocation heterozygotes.
D) translocation homozygotes.
E) reciprocal crossovers.

Question 5

When a crossover occurs within the inversion loop of a pericentric inversion,each recombinant chromatid will have

A) two centromeres.
B) a duplication of one region.
C) translocation.
D) no centromeres.
E) exactly the same length as before the inversion.

Question 6

Individuals who are deletion heterozygotes have a greatly increased risk of losing both copies of certain genes and developing cancer.One such disease in humans is

A) triplolethal.
B) scarlet eyes.
C) retinoblastoma.
D) cataracts.
E) sickle cell anemia.

Question 7

Inversions may be hard to detect because they

A) never visibly change chromosome banding patterns.
B) increase recombination in heterozygotes.
C) do not usually cause an abnormal phenotype.
D) normally are removed immediately in natural populations.
E) cannot involve more than 1000bp.

Question 8

Which of the following adds material to the genome?

A) inversion
B) duplication
C) deletion
D) translocation
E) translation

Question 9

Sometimes a piece of one chromosome attaches to another chromosome.This is known as a(n)

A) inversion.
B) duplication.
C) deletion.
D) translocation.
E) replication.

Question 10

In higher organisms,it is usually difficult to distinguish with genetic analysis small deletions in one gene from

A) heterozygotes.
B) small duplications.
C) monosomies.
D) point mutations.
E) trisomies.

Question 11

Which of the following is most likely to produce a chromosomal inversion?

A) aneuploidy
B) one double-strand breakage on each of two different chromosomes
C) transposition of a retrotransposon
D) double-strand breakage at two positions on the same chromosomes
E) Robertsonian translocation

Question 12

Which of the following does not happen when an intragenic inversion occurs?

A) One part of the gene is relocated to a distant region of the chromosome.
B) One part of the gene stays at its original site.
C) One part of the gene is relocated to another chromosome.
D) The gene's function remains unaffected.
E) The length of the chromosome remains unaffected.

Question 13

Which of the following removes material from the genome?

A) inversion
B) duplication
C) deletion
D) translocation
E) replication

Question 14

During the pairing of homologues in prophase of meiosis I,the region of a normal,nondeleted chromosome that has nothing with which to recombine forms a so-called

A) inversion loop.
B) deletion heterozygote.
C) crossover suppressor.
D) D loop.
E) deletion loop.

Question 15

Which of the following is least likely to show a problem during meiosis?

A) translocation heterozygote
B) translocation homozygote
C) paracentric inversion
D) pericentric inversion
E) triploid

Question 16

Duplications arise by any of the following except

A) chromosomal breakage and faulty repair.
B) unequal crossing-over.
C) errors in replication.
D) alkylating mutagens.
E) errors in recombination.

Question 17

In general,which of the following usually has a greater chance of lethality than the others?

A) inversion
B) duplication
C) deletion
D) translocation
E) transcription

Question 18

The type of chromosomal rearrangement that reorganizes the DNA sequence within one chromosome is known as a(n)

A) inversion.
B) duplication.
C) deletion.
D) translocation.
E) replication.

Question 19

Robertsonian translocations result from which of the following?

A) Breaks occur at or near the centromeres of two acrocentric chromosomes followed by the reciprocal exchange of broken parts.
B) A part of one chromosome becomes attached to a nonhomologous chromosome.
C) Unequal crossing over occurs during meiosis.
D) There is fusion of two small chromosomes end-to-end such that a double centromere occurs.
E) Nondisjunction during meiosis.

Question 20

Which of the following is not considered a chromosomal rearrangement?

A) inversion
B) duplication
C) deletion
D) translocation
E) replication

Question 21

The most common human aneuploidy is trisomy 21,Down syndrome.All of the effects listed below may be seen in this syndrome except

A) death always by age 25.
B) mental retardation.
C) skeletal abnormalities.
D) heart defects.
E) increased susceptibility to infection.

Question 22

Which of the following would be most helpful in mapping the genes that cause Down syndrome?

A) linkage mapping
B) Ac elements
C) fluorescently labeled probes
D) LINEs
E) SINEs

Question 23

Which of the following sex chromosome aneuploidies is not usually seen in live births?

A) XO
B) XXY
C) YO
D) XXX
E) None of the choices are correct.

Question 24

Which of the following do translocations and inversions not have in common?

A) don't alter the amount of DNA in the genome
B) able to alter gene function
C) use of inversion loops during crossing over
D) catalysts of speciation
E) able to change gene order

Question 25

In Drosophila,a gynandromorph,which is composed of equal parts of male and female tissue,results from

A) an XX female losing one X chromosome during the first mitotic division after fertilization.
B) an egg carrying an X chromosome fertilized by a Y-carrying sperm.
C) a normal egg fertilized by both an X-carrying sperm and a Y-carrying sperm.
D) the fusion of a female embryo with a male embryo.
E) the fusion of a female egg by an XX sperm.

Question 26

The genus Triticale is a new genus of the various allopolyploid hybrids between wheat and rye.Some of the members of this genus show agricultural promise because

A) wheat has a high yield.
B) rye adapts well to unfavorable environments.
C) wheat has a high level of protein.
D) rye has a high level of lysine.
E) All of the choices are correct.

Question 27

Triploid organisms usually result from

A) the union of haploid and diploid gametes.
B) unequal disjunction during embryogenesis.
C) propagation of fused cell lines.
D) fusion of three gametes simultaneously.
E) duplication of a haploid genome.

Question 28

In terms of evolution,what is the most significant outcome of translocation in a species' genome?

A) production of gene families
B) development of two species due to reproductive isolation
C) eventual extinction due to semisterility
D) Down syndrome
E) Klinefelter syndrome

Question 29

Down syndrome can result from

A) three copies of chromosome 21.
B) a translocation of a part of chromosome 21.
C) a reciprocal translocation between any two autosomes.
D) both A and B

Question 30

In terms of evolution,what is the most frequent outcome of repeated duplications of different segments of a species' genome?

A) aneuploidy
B) semisterility
C) gene families
D) cancer
E) speciation

Question 31

Which of the following rarely,if ever,results in a positive force for evolution?

A) polyploidy
B) allopolyploidy
C) trisomy
D) amphidiploidy
E) euploidy

Question 32

Which of the following would be most difficult to identify by comparative genomic hybridization (CGH)?

A) duplication
B) deletion
C) monosomy
D) base substitution
E) trisomy

Question 33

During mitosis,if all the chromosomes in a diploid tissue fail to separate after replication,the resulting daughter cells will be

A) monoploid.
B) tetrasomic.
C) triploid.
D) tetraploid.
E) trisomic.

Question 34

Turner syndrome,XO,is a sex chromosome aneuploidy.Of the effects listed below,which one is not usually seen in this syndrome?

A) unusually short stature
B) infertility
C) skeletal abnormalities
D) unusually long limbs
E) abnormal karyotype

Question 35

Hybrids in which the chromosome sets come from two distinct,though related,species are known as

A) autopolyploids.
B) allopolyploids.
C) amphiploids.
D) bivalents.
E) amphivalents.

Question 36

Retrotransposons and retroviruses have structural parallels.Which of the following also shares structural parallels with them?

A) tRNA
B) dsDNA
C) rRNA
D) mRNA
E) plasmid DNA

Question 37

Which of the following is not an example of a euploid condition?

A) triploidy
B) diploidy
C) trisomy 21
D) tetraploidy
E) haploidy

Question 38

The various types of transposable elements have many things in common.Which of the following is not a usual characteristic of them?

A) larger than 50 kb
B) may be present in a genome from one to thousands of times
C) found only in a select group of organisms
D) need not be sequences that do something for the organism
E) can alter gene expression

Question 39

Which of the following is an aneuploidy?

A) triploid
B) tetraploid
C) trisomy
D) haploid
E) monoploid

Question 40

Barbara McClintock is most closely associated with which of the following?

A) the initial discovery of genetic transposition
B) the discovery of transposable elements in corn
C) the mutation rate in translocation heterozygotes
D) the demonstration of the presence of transposable elements in polytene chromosomes
E) the discovery of polyploidy

Question 41

Changes in chromosome number include aneuploidy,monoploidy,polyploidy,and duplications.

Question 42

Euploid cells contain only incomplete sets of chromosomes.

Question 43

Genetic imbalance results from polyploidy.

Question 44

One of the evolutionary effects of repeated duplications in a species genome could be development of gene families.

Question 45

Reciprocal translocations are usually phenotypically normal because they have neither lost nor gained genetic material.

Question 46

The mouse genome has high synteny with the human genome since about 342 DNA blocks are simply rearranged between the two genomes.

Question 47

Crossing-over within an inversion loop always produces unbalanced recombinant chromatids.

Question 48

When comparing mouse and human Giemsa-stained karyotypes,we see no conservation of banding patterns.

Question 49

A hallmark of transposons is that their ends are inverted repeats of each other.

Question 50

What is the difference between the Ac and Ds elements identified by McClintock?

A) Ac can move on its own or in the presence of Ds.
B) Ds can move on its own or in the presence of Ac.
C) Only the Ds element can disrupt genes.
D) Ac can move only in the presence of Ds.
E) Only the Ac element can disrupt genes.

Question 51

Karyotypes generally remain constant within a species because rearrangements and changes in chromosome number occur infrequently.

Question 52

Reciprocal translocations in a species' genome may be one way that new species arise.

Question 53

Which of the following causes yellow corn kernels to gain red spots?

A) insertion of a transposable element in a gene for yellow pigment production
B) excision of a transposable element from a gene for yellow pigment production
C) transposable element induced transactivation of a pigment producing gene
D) insertion of a transposable element in a gene for red pigment production
E) excision of a transposable element from a gene for red pigment production

Question 54

Down syndrome is an example of triploidy.

Question 55

Recessive mutations can often be uncovered by deletions in heterozygotes.

Question 56

Most duplications have no obvious phenotypic consequences and can be detected only by cytological or molecular means.

Question 57

Duplication of chromosomal segments rarely has an effect on the evolution of genomes.

Question 58

An acentric fragment is an inversion crossover product lacking a centromere.

Question 59

Deletion may arise from errors in replication,from faulty meiotic or mitotic recombination,and from exposure to X-rays.

Question 60

Homozygosity for a deletion is often,but not always,lethal.

Question 61

Explain the possible effects that a transposable element may have on a gene.

Question 62

You have discovered an altered phenotype and cloned the gene responsible.However,the gene you cloned appears to have an unusual sequence in it.In order to determine the chromosomal location of your new gene,you perform FISH,using only the unusual sequence,on several animals.To your surprise,the FISH results suggest that each animal contains the gene on a different chromosome.How would you interpret your results?

Question 63

What is the difference between alternate and an adjacent-1 segregation or an adjacent-2 segregation pattern?

Question 64

You are a master gardener and your favorite tomato plant is very sensitive to a pesticide called DEADBUG.You wish to make your special tomato plants resistant to the pesticide that you spray on other bushes in your garden.Using microbial techniques,give sufficient and complete details of how you would do this (include ploidy status).

Question 65

Describe how an inversion heterozygote can reduce the number of recombinant progeny.

Question 66

What are the possible effects of transposable elements on gene function,and how do these relate to evolution?

Question 67

Why do inversions act as crossover suppressors?

Question 68

Discuss how deletions and duplications may contribute to evolution.

Question 69

Discuss why triploid organisms are almost always sterile.

Question 70

What is a balancer chromosome?

Question 71

Explain the differences between chromosomal rearrangements and changes in chromosome number.Cite at least one example of each.

Question 72

You are mapping traits in your favorite organism but unbeknownst to you,your laboratory model organism contains a rare deletion.How will your mapping results be affected?

Question 73

What is pseudolinkage?

Question 74

What is the difference between tandem and nontandem duplications?

Question 75

Explain the mechanism by which aneuploidy occurs.

Question 76

Why do rearrangements and changes in chromosome number sometimes affect gene activity or gene transmission?

Question 77

Explain how data from the linkage groups of the mouse can be used as a resource for assessing human linkage groups.

Question 78

Discuss the several effects that translocations and inversions have in common.

Question 79

What are LINEs and SINEs?

Question 80

We now know that several organisms have a high degree of synteny at the genomic level.You wish to test the hypothesis that the laboratory mouse and humans share genomic similarities.What tests would you complete and given that we now know that the mouse and human genomes are highly syntenic,what results would you expect?