Test Bank | Ch10 Chromosomes & Transposable Elements – 7e

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1) Select the two primary components of chromatin.

A) DNA
B) Proteins
C) RNA
D) Lipids
E) Carbohydrates

2) You wish to repeat the Noll experiment. However, after you run your gel for an appropriate amount of time, you are dismayed to find that all of the DNA is present at the very top of the agarose gel. What mistakes might you have made in your experiment? (Check all that apply.)

A) You forgot to add DNase I to your DNA.
B) You didn't sufficiently isolate your DNA from the attached proteins.
C) You forgot to stain the gel with ethidium bromide.
D) You added too much DNase I to your DNA.

3) How many origins of replication are there on a bacterial chromosome?

A) 0
B) 1
C) 2
D) More than two

4) Where is the bacterial chromosome located?

A) Nucleus
B) Nucleolus
C) Nucleoid
D) Nuclear envelope

5) What is a mechanism of condensation shared by both prokaryotes and eukaryotes?

A) Nucleosomes
B) Loop domains
C) 30 nm fiber
D) None of these choices are correct.

6) Loop domains in prokaryotes involve how many base pairs?

A) 10,000
B) 100,000
C) 1000
D) 50,000

7) Negative supercoiling in bacteria __________.

A) makes the chromosomal DNA more compact
B) creates tension because of the underwinding of the DNA
C) can promote DNA strand separations in small regions
D) All of these choices are correct.

8) Turning the DNA helix to the right causes __________.

A) positive supercoiling
B) overwinding
C) All of these choices are correct.

9) DNA topoisomerase I does which of the following?

A) Relaxes negative supercoils
B) Relaxes positive supercoils
C) Introduces negative supercoils
D) More than one of these choices are correct.

10) Quinolone-based drugs are used as antibiotics. How do they kill bacteria?

A) They inhibit DNA gyrase.
B) They inhibit DNA compaction.
C) They inhibit DNA replication.
D) They inhibit eukaryotic topoisomerases.

11) Why do some amphibians have so much more DNA in their haploid genome than humans?

A) Amphibians have more repetitive sequences than do humans.
B) Amphibians are more biologically complex than mammals.
C) Amphibians have more genes than do humans.
D) Amphibians are tetraploid, while humans are diploid.

12) Where do kinetochores form onchromosomes?

A) Telomeres
B) Specific genes on the chromosome
C) Centromeres
D) They don't attach to DNA

13) Which of the following is found at the end of a eukaryotic chromosome?

A) Telomeres
B) Centromeres
C) Kinetochores
D) Origins of replication

14) An Alu sequence is an example of what?

A) Retroelement
B) Transposable element
C) Highly repetitive DNA
D) All of these choices are correct.

15) The majority of the nonrepetitive genes in an organism are found in which of the following?

A) Unique sequences
B) Moderately repetitive sequences
C) Highly repetitive sequences
D) None of these choices are correct.

16) Unique sequences make up approximately what percent of the human genome?

A) 5%
B) 25%
C) 41%
D) 81%

17) How many types of histone proteins are there?

A) 4
B) 5
C) 7
D) 8

18) What types of amino acids are most responsible for the binding of histones to DNA?

A) Hydrophobic amino acids
B) Polar amino acids
C) Positively charged amino acids
D) Negatively charged amino acids

19) About how many bases of DNA wrap around a histone complex?

A) < 50
B) 150
C) 200
D) > 1,000

20) Digesting chromatin with a high concentration of DNAse I would yield fragments of what approximate size?

A) 200
B) 400
C) 600
D) 1100

21) The two processes of wrapping DNA on nucleosomes and arranging them into a 30-nm fiber shorten the DNA by how much?

A) 30-fold
B) 50 fold
C) 1 million-fold
D) 3 million-fold

22) Areas of the chromosome that remain highly condensed are called __________.

A) euchromatin
B) facultative heterochromatin
C) constitutive heterochromatin
D) chromosome territories

23) Which of the following is critical in thealignment of sister chromatids during metaphase?

A) Radial loop domains
B) Cohesin
C) Centromeres
D) Nucleosomes
E) Condensin

24) Which of the following represents the lowest level of chromosome condensation?

A) Radial loop domain
B) 30 nm fibers
C) Heterochromatin
D) Nucleosome
E) Euchromatin

25) The function of condensin is to __________.

A) cause the chromosomes to decondense following mitosis
B) coat the chromosomes and condense them into heterochromatin through the compaction of radial loops
C) hold the DNA to the histone proteins in the nucleosome core particle
D) trigger DNA to be compacted in a nucleosome core particle
E) None of these choices are correct.

26) Which of the following is not part of the structure of the nucleosome core particle?

A) It is composed ofan octamer of proteins.
B) There is a linker region between two nucleosomes of between 20 and 100 bp.
C) There are twocopies each of H2A, H2B, H3 and H4.
D) The DNA is wrappedaround the core slightly over two complete turns.
E) The DNA wrappedaround the core contains 146-147 base pairs.

27) Which of the following is correctly matched with its description?

A) Highly repetitive DNA contains transposable elements and genes that are expressed in abundance and thus have many copies.
B) Moderately repetitive DNA contains unique sequences, such as genes found inone or a few copies.
C) Nonrepetitive DNA is composed of thousands of copies of many short repeats.
D) Moderately repetitive DNA contains retro elements, such as the Alusequence.
E) Moderately repetitive DNA contains transposable elements and genes that are expressed in abundance and thus have many copies.

28) Which of the following is not a mechanism used bybacteria to condense their DNA?

A) Supercoiling
B) Packaging the DNA with histone proteins
C) Looping of the DNA
D) Increasing or decreasing the number of turns in the DNA
E) Forming micro and macrodomains using nucleoid-associated proteins

29) The DNA of a bacterial cell must be compacted about _______ fold to fit within the confines of the cell.

A) 10-
B) 100-
C) 150-
D) 1000-
E) 1,000,000-

30) The zig-zag model is associated with the __________ level of DNA organization.

A) histone
B) 11-nm fiber
C) beads-on-a-string
D) 30-nm fiber
E) scaffoldprotein

31) The origins of replication in eukaryotic chromosomes are spaced about every _______ base pairs.

A) 100,000
B) 1000
C) 100
D) 10
E) 500

32) A nucleosome is a combination of __________ and __________.

A) histone proteins; scaffold proteins
B) RNA; transcription proteins
C) DNA; histone proteins
D) RNA; histone proteins
E) DNA; scaffold proteins

33) Why do positively charged amino acids appear more often than usual in histone proteins?

A) Histones have a higher molecular mass, which improves DNA compaction.
B) Histones are strongly attracted to the positively charged phosphate backbone of DNA.
C) Histones and DNA have opposite charges, which improves the compaction of DNA into nucleosomes.
D) Histones and DNA have the same charge, which improves the compaction of DNA into nucleosomes.

34) The individual who first proposed the existence of transposable elements was __________.

A) Sturtevant
B) Morgan
C) McClintock
D) Franklin
E) Watson

35) Which of the following genes was mobile in McClintock's experiments with mutable sites in corn?

A) Ds
B) C
C) Sh
D) Wx
E) All of these choices are correct.

36) Transposons that utilize an RNA intermediate for transposition are called __________.

A) IS elements
B) retroviruses
C) retrotransposons
D) non-transposable elements

37) Which enyme catalyzes the transposition event when a transposon moves?

A) Integrase
B) Jumpase
C) Splicase
D) Transposase

38) Insertion sequences can be identified by which of the following?

A) Presence of an integrase enzyme
B) High level of mutation
C) Presence of inverted repeats at the end of the sequence
D) Presence of a reverse transcriptase enzyme

39) Long-terminal repeats are unique to which group of transposons?

A) Composite transposon
B) Non-viral retro element
C) Viral-like retro element
D) Replicative transposon
E) Insertion sequence

40) Direct repeats __________.

A) are also called target-site duplications
B) are oriented in the same direction
C) are adjacent to both ends of any TE
D) All of these choices are correct.

41) Which enzyme is unique to the retro elements?

A) Reverse transcriptase
B) Reverse resolvase
C) Transposase
D) Integrase
E) Reverse integrase

42) Which of the following is an example of a transposable element in humans?

A) Alu
B) P elements
C) Mu
D) Ty

43) What is the selfish DNA theory?

A) A theory that explains how DNA point mutations are repaired within thegenome.
B) A theory that explains how transposable elements are repaired within thegenome.
C) A theory thatattempts to explain the proliferation of transposable elements in a genome bycomparing it to the action of a parasite.
D) A theory that attempts to explain how the proliferation of transposons improves the evolutionary advantage of the host organism.

44) A chromosome territory is defined as __________.

A) a region in the nucleus that is occupied by a single chromosome
B) a region on a chromosome that is devoid of nucleosomes
C) a region on a chromosome that has no protein encoding genes
D) a region in the nucleus that may have several chromosomes

45) The correct order of compaction from least compacted to most compacted would be __________.

A) naked DNA, 30-nm fiber, nucleosome, loop domain, metaphase chromosome
B) naked DNA,loop domain, 30-nm fiber, nucleosome, metaphase chromosome
C) naked DNA, nucleosome, 30-nm fiber, loop domain, metaphase chromosome
D) naked DNA, metaphase chromosome, loop domain, 30-nm fiber, nucleosome

46) A transposon is inserted into the sequence 5' GACTC 3'. Following simple transposition into this site, what sequences flank the transposon?

A) 5' GACTC 3'; 5' GACTC 3'
B) 5' GACTC 3'; 5' CTCAG 3'
C) 5' CTCAG 3'; 5' GACTC 3'
D) 5' CTCAG 3'; 5' CTCAG 3'

47) You have discovered a new gene in corn. The wild type allele of this gene ( S) is dominant and makes corn kernels have a smooth surface, whereas the recessive allele ( s) makes the corn kernel appear to be wrinkled. You breed a corn strain that has genotype SSS (recall that the endosperm of corn kernels is triploid). If the Ds transposon is present in one of the S alleles in the cells of the kernel, what will be the phenotype of the corn kernel?Assume the transposon can continue to move during kernel growth.

A) All wrinkled
B) All smooth
C) Smooth with a few wrinkled spots from cells where the transposon was inserted
D) Wrinkled with a few smooth spots from cells where the transposon excised

48) You have discovered a new gene in corn. The wild type allele of this gene ( S) is dominant and makes corn kernels have a smooth surface, whereas the recessive allele ( s) makes the corn kernel appear to be wrinkled. You breed a corn strain that has genotype Sss(recall that the endosperm of corn kernels is triploid). If the Dstransposon is present in the S allele in the cells of the kernel, what will be the phenotype of the corn kernel? Assume the transposon can continue to move during kernel growth.

A) All wrinkled
B) All smooth
C) Smooth with a few wrinkled spots from cells where the transposon was inserted
D) Wrinkled with a few smooth spots from cells where the transposon excised

49) You are studying a protein in the frog Xenopus laevis. This organism has a high percentage of transposable elements (TEs) in its genome. After several months of experiments, you start experiencing strange results. It appears that your protein is no longer being made! You look at the chromosomes from the cells where the protein is not being produced, and they all appear normal. You also sequence the coding region of your gene and it has a normal sequence. What is the most likely explanation for your missing protein?

A) A chromosomal breakage has occurred due to excision of a TE.
B) A mutation has occurred due to incorrect excision of a TE from your gene.
C) A TE has inserted in the regulatory sequences for your gene, altering gene regulation.
D) Exon shuffling has occurred, and there is a new exon in your gene.

50) You are working in a lab and isolate a mammalian cohesin mutant that is unable to be cleaved by separase. What will be the result of this mutation?

A) The cells will be stuck in anaphase, unable to separate sister chromatids.
B) The cells will be stuck in metaphase, unable to properly align chromosomes.
C) The cells will be stuck in S phase, unable to form sister chromatids.
D) The cells will proceed through the cell cycle normally.

51) One would expect heterochromatic regions of DNA to be more compacted than euchromatic regions.

⊚ true
⊚ false

52) Overwinding of the DNA decreases the number of turns in the double helix, and thus results in supercoils in the DNA.

⊚ true
⊚ false

53) The term genome refers to the complete complement of genetic material that an organism possesses.

⊚ true
⊚ false

54) The majority of bacterial DNA is negatively supercoiled.

⊚ true
⊚ false

55) The 30-nm fiber is formed from arrays of nucleosomes.

⊚ true
⊚ false

56) The different DNA configurations that are generated by supercoiling are called topoisomers of one another.

⊚ true
⊚ false

57) The DNA-protein complex in eukaryotic chromosomes is called the genome.

⊚ true
⊚ false

58) The is a strong relationship between organism complexity and genome size in eukaryotes.

⊚ true
⊚ false

59) High numbers of LINEs and SINEs may be due to transposable element activity.

⊚ true
⊚ false

60) Transposase is involved with removing the transposable element from its current location.

⊚ true
⊚ false