Deck 18: The Structural Basis of Cellular Information: DNA, chromosomes, and the Nucleus

Question 1

Which of the following statements regarding the WatsonCrick model of DNA is not accurate?

A)It is the most common biological form.
B)It is a left-handed helix.
C)It is antiparallel.
D)The bases are "stacked" in the center of the molecule.
E)The backbone consists of alternating sugars and phosphates.

Answer 1

B

Question 2

DNA isolated from cow liver cells contains 28% A; what percent will be C?

A)14%
B)22%
C)28%
D)36%
E)56%

Answer 2

B

Question 3

Restriction enzymes typically recognize

A)sequences in threefold symmetry.
B)single-stranded DNA only.
C)specific palindromic sequences.
D)several nucleotide sequences simultaneously.
E)all of the above

Answer 3

C

Question 4

Following reports that stained chromosomes "disappeared" while observing cell division,scientists in the early 1900s determined the molecule of heredity to be

A)DNA.
B)RNA.
C)protein.
D)lipids.
E)carbohydrates.

Question 5

The scientist credited with the discovery of DNA,which he called "nuclein," from salmon sperm in 1869 is

A)Johann Friedrich Meischer.
B)Eduard Zacharias.
C)Fredrick Griffiths.
D)Martha Chase.
E)Oswald Avery.

Question 6

Which of the following are components of Chargaff's rules of bases?

A)purines = pyrimidines
B)C + T = A + G
C)A + T = G + C
D)G = C
E)all of the above

Question 7

DNA isolated from Aspergillis has an adenine content of 25%.Based upon this information,what is the %G + C within the Aspergillis DNA?

A)0%
B)25%
C)50%
D)75%
E)The answer cannot be determined from this information.

Question 8

Avery,MacLeod,and McCarty (1944)demonstrated that DNA was the molecule of heredity by treating heat-killed Streptococcus pneumoniae S (smooth)strain with DNase,thereby preventing transfer of the "transforming substance" from the killed S strain to the live R (rough)strain when the two were mixed together and injected into mice.Another way that one could demonstrate transformation in bacteria would be to extract DNA from

A)an R strain and mix with cells of an S strain.
B)both S and R strains and mix to allow recombination to take place.
C)an ampicillin-sensitive strain and mix with cells of an ampicillin-resistant strain.
D)an S strain and mix with cells of an R strain.
E)none of the above

Question 9

Which of the following shows Chargaff's equivalence?

A)mRNA
B)single-stranded DNA
C)tRNA
D)synthetic DNA (one strand all A, the other all T)
E)all of the above

Question 10

DNA is different from RNA in that

A)RNA contains an additional oxygen atom on the ribose sugar.
B)RNA is made up five bases, whereas DNA is made up of four.
C)RNA cannot exist as a double helix.
D)in general, RNA molecules are longer than DNA molecules.
E)all of the above

Question 11

In 1928,Frederick Griffith's experiments with Streptococcus pneumoniae suggested that

A)bacteria do not incorporate the DNA of other bacteria.
B)attenuated R (rough)bacteria easily revert to the wild type (virulent).
C)DNA was conclusively the molecule of heredity.
D)heat-killed bacteria could somehow "transform" live bacteria.
E)all of the above

Question 12

When examining a five-carbon sugar to determine if it is ribose or deoxyribose,one looks to see if there are two H on the _____ carbon in the structure.

A)1'
B)2'
C)3'
D)4'
E)5'

Question 13

Circular DNA molecules found in nature (such as bacterial,viral,or mitochondrial DNA)are

A)positively supercoiled.
B)negatively supercoiled.
C)not supercoiled, due to their small size.
D)always oriented in a triple helix to conserve space.
E)always in the relaxed state.

Question 14

The normal gene for hemoglobin was isolated,cloned,and subjected to restriction enzyme digestion with BamHI.Following gel electrophoresis,three bands are routinely obtained.However,following the same procedure with the hemoglobin gene from an individual with sickle-cell anemia,four bands are routinely obtained.These data suggest that

A)the mutation associated with sickle-cell anemia results in DNA that breaks easily.
B)the mutation associated with sickle-cell anemia results in the loss of a BamHI cut site.
C)the mutation associated with sickle-cell anemia results in several new enzyme cut sites for a variety of restriction enzymes.
D)the mutation associated with sickle-cell anemia results in the gain of a BamHI cut site.
E)the assay was not performed correctly.

Question 15

In experiments designed as those of Hershey and Chase (1952),³⁵S was added to a virus replicating within its bacterial host.The new virions were carefully isolated and used to infect fresh bacterial cells in the absence of any radioisotopes.Where would you expect to find the ³⁵S radioisotope?

A)in the phage ghosts
B)in the bacterial matrix proteins
C)in the bacterial DNA
D)in the nucleic acid of the new virions
E)in the protein coat of the new virions

Question 16

Base sequence variations between individuals that result from point mutations are called

A)polymorphs.
B)small nuclear polymorphisms.
C)deletions.
D)single nucleotide polymorphisms.
E)restriction fragment length polymorphisms.

Question 17

The 5' end of a DNA molecule can be chemically distinguished from the 3' end because there is a(n)__________ group at the 5' end and a(n)__________ group at the 3' end.

A) NH₃; COOH
B)PO₄; SO₄
C)OH; H
D)PO₄; OH
E)none of the aboᵥe

Question 18

A recently isolated bacterial strain has been given to you for general characterization of the genome.You begin by isolating the DNA and subjecting it to thermal denaturation.You use Escherichia coli DNA as a reference (A + T = G +C).
Figure 18.1
Based on the information in the graph, you can determine that the DNA has a high

A)G-C content with respect to E. coli.
B)pyrimidine content with respect to E. coli.
C)A-T content with respect to E. coli.
D)purine content, with respect to E. coli.
E)none of the above

Question 19

The specific field of study that examines the gene products of a genome is known as

A)genomics.
B)bioinformatics.
C)annotation.
D)proteomics.
E)none of the above

Question 20

An example of a purine is

A)thymine.
B)guanine.
C)acridine.
D)cytosine.
E)uracil.

Question 21

Interspersed repeat DNA

A)constitutes 25-40% of most mammalian genomes.
B)is clustered in the genome.
C)is approximately 10⁵-10⁷ bp in length for each repeat.
D)occurs in gene families, such as the Alu family.
E)both choices A and D

Question 22

You are using genetic engineering to design a protein that needs to be synthesized in the cytoplasm and then localized in the nucleus of the cell.To accomplish this,one could add

A)a nuclear localization signal into the DNA that will be present in the mature protein.
B)the compound during mitosis, at a time when the nuclear membrane is dispersed.
C)a nucleotide or few nucleotides to the protein.
D)a series of specific polysaccharides to the carboxyterminal end of the protein.
E)all of the above

Question 23

You and your neighbor have how much difference in your DNA sequence?

A)0.01%
B)0.1%
C)1%
D)10%
E)25%

Question 24

The nucleolus

A)is surrounded by a thin nucleolar membrane.
B)is found, one per cell, in eukaryotes.
C)contains the NOR of rRNA genes.
D)synthesizes ribosomal proteins.
E)all of the above

Question 25

You isolate a new bacterium from soil with a revolutionary new growth technique.You are interested in characterizing the genome of this organism using restriction enzymes.The first enzyme chosen should be one that will cut the genome infrequently,allowing you to do more detailed fine mapping at a later date.Of the following choices,the best enzyme to choose for your task would be (NOTE: P = a purine base; Y = a pyrimidine base)

A)HpaI (CCGG).
B)TaqI (TCGA).
C)EcoRI (GAATTC).
D)HindII (GTYPAC).
E)NotI (GCGGCCGC).

Question 26

With which organelle membrane would you expect to find the receptor protein importin?

A)mitochondrion
B)nucleolus
C)chloroplast
D)plastid
E)nucleus

Question 27

Using the Sanger method of DNA sequencing,results in the figure below are obtained following gel electrophoresis of the DNA fragments.

Figure 18.2
A total of 21 nucleotides has been sequenced. What is the sequence of these nucleotides?

A)5'-ACCGTTTGCAGAACGTTCCCA-3'
B)5'-ACCCACGTTAAAGACCCGTTT-3'
C)5'-AAAAACCCCCCCGGGGTTTTT-3'
D)5'-ACCCTTGCAAGACGTTTGCCA-3'
E)none of the above
Answer: D

Question 28

Which of the following is the correct order of the levels of DNA packaging in eukaryotic chromosomes?

A)nucleosome → chromatin fiber → looped domains → heterochromatin
B)nucleosome → looped domains → chromatin fiber → heterochromatin
C)heterochromatin → nucleosome → chromatin fiber → looped domains
D)chromatin fiber → heterochromatin → nucleosome → looped domains
E)chromatin fiber → nucleosome → looped domains → heterochromatin

Question 29

Which of the following terms is used to indicate the entire set of RNA molecules that can be made by a cell?

A)transcriptomes
B)genomes
C)proteomes
D)desmosomes
E)total RNA

Question 30

A husband and wife are in the process of getting a divorce.During child-support hearings,the husband states that he should not pay child support as he feels that the child was actually fathered by one of the woman's various lovers.DNA restriction analysis was performed,with the results illustrated in the diagram below.

Figure 18.3
The DNA of the husband in this case can be found in lane 3, whereas that of the suspected father is in lane 4. Based on this information,

A)the husband is definitely the child's father.
B)the husband is definitely not the child's father.
C)either man could be the father, and more tests are needed to discern paternity.
D)neither man in question is the child's biological father.
Answer: B

Question 31

Eukaryotic-like (possessing a defined nucleus)cells were obtained from a Martian soil sample.The nucleus was carefully isolated and the chromatin obtained.The fibers had a "beads on a string" appearance,suggesting some type of "histones." Following digestion with micrococcal nuclease,protein removal,and gel electrophoresis,DNA fragments were obtained that are multiples of 280 base pairs in length.Longer incubation with micrococcal nuclease prior to protein removal results in fragments 200 base pairs in length.The amount of DNA that is wrapped around the "core histones" is therefore

A)80 base pairs in length.
B)200 base pairs in length.
C)360 base pairs in length.
D)480 base pairs in length.
E)Not enough information is given to determine the answer.

Question 32

You wish to use mRNA profiles to examine the genes of a cell that are ultimately translated into proteins during times of stress.As a result,you are investigating a portion of the cell's

A)spliceosome.
B)genome.
C)proteome.
D)transcriptome.
E)microarray.

Question 33

Numerous Xenopus cells were exposed to various amounts of ultraviolet light.Some of the resulting cells were observed to lack nucleoli.As a result,one would expect that the cell could not

A)perform cellular respiration.
B)replicate its DNA.
C)perform photosynthesis.
D)synthesize rRNA.
E)none of the above

Question 34

The nuclear membrane functions as a

A)means of separating nuclear and cytoplasmic constituents.
B)means of localization of the chromosomes within the cell.
C)selective barrier, allowing certain substances in or out.
D)means of sequestering many of the mRNA processing activities from the cytosol.
E)all of the above

Question 35

All of the following structures are found within the nucleus of a eukaryotic cell except

A)speckles.
B)Cajal bodies.
C)promyeloctic leukemia (PML)bodies.
D)nucleolus.
E)All of the above are found in the nucleus.

Question 36

A variety of E.coli clones have been isolated,and the DNA has been extracted,digested with restriction enzymes,denatured,separated by gel electrophoresis,and transferred to nylon membrane by the Southern blot procedure.A radioactive probe is used that hybridizes with a gene of interest.The DNA corresponding to a single clone yields a single DNA band after probing the blot.Based on this information only,

A)all of the clones tested, except the one described, have the gene of interest.
B)only the one clone described has the gene of interest.
C)the gene of interest is located entirely on the DNA band visualized.
D)the part of the gene recognized by the probe is located on the DNA band visualized.
E)both choices B and D

Question 37

The mitochondrial DNA can be used to identify a species based upon

A)NADH dehydrogenase sequences.
B)variation in the mitochondrial ribosomes.
C)648 bp DNA bar code region.
D)leucine codon usage.
E)none of the above

Question 38

With regard to DNA packaging,prokaryotic chromosomes

A)are devoid of histone or histone-like proteins.
B)are, in general, positively supercoiled.
C)have no higher-level structure, such as looped domains.
D)use RNA to contribute to chromosomal packaging.
E)none of the above

Question 39

Which one of the following is not characteristic of prokaryotic genomes?

A)gene arranged in operons
B)distinct replication site
C)presence of introns
D)may have histone-like proteins associated with the chromatin
E)found in the nucleoid

Question 40

In the Sanger method of DNA sequencing,incorporation of the nucleotides stops because

A)the dideoxynucleotide analogs have no 3'-OH group to continue DNA synthesis.
B)the dideoxynucleotide analogs have no 5'-OH group to continue DNA synthesis.
C)the dideoxynucleotide analogs have no 2'-OH group to continue DNA synthesis.
D)the mixture is heated to 92°C to stop DNA synthesis at specific time intervals.
E)the dideoxynucleotide analogs are in greater concentration than the actual nucleotides.

Question 41

________ ,also known as "jumping genes," are examples of mobile DNA elements.

Question 42

SNPs located near each other on chromosomes are inherited as blocks known as ________.

Question 43

The protein ________ is very important for the investigation of protein products produced by an organism.

Question 44

Because of its antiparallel nature,DNA is often referred to as a ________.

Question 45

The name given to double-stranded DNA that is twisted upon itself is ________.

Question 46

________ is the name given to DNA characterization based upon digestion of DNA with specific restriction enzymes.

Question 47

You are given the task of restriction-mapping a portion of a chromosome.Given is a 7.0 kb fragment.You digest the fragment with BamHI and,upon gel electrophoresis,observe a band at 5.0 kb and 1.0 kb.When you digest the fragment with the enzyme HindII,you observe fragment bands at 4 kb and 3 kb.When you digest the 7.0 kb fragment with both enzymes,you observe bands at 3 kb,2 kb,and 1 kb.Based on this information,draw the restriction map of the 7 kb fragment.

Question 48

Describe constitutive heterochromatin and facultative heterochromatin. Based upon this information,what would you predict would happen during the embryonic development of an organism if some regions of facultative heterochromatin were changed to constitutive regions?

Question 49

A novel protozoan was discovered on a rock sample brought back to Earth from Mars.Your task is to determine the lengths of DNA associated with its nucleosomes so that a colleague can then determine the nature of the proteins that comprise the nucleosome.How would you go about determining the lengths of these DNA fragments?

Question 50

The data below were obtained as the result of the Sanger method of DNA sequencing.Determine the DNA sequence,making sure to indicate 5' and 3' ends,and add the sequence for the complementary strand.

Question 51

________ are the entire set of RNAs that can be produced by a genome.

Question 52

Common SNPs may be important in causing ________ in humans or in ________ of disorders.

Question 53

________ demonstrated that there were equivalent amounts of adenine and thymine and equivalent amounts of guanine and cytosine.

Question 54

The name given to the area of study that is involved with the determination of the entire DNA sequence of an organism is known as ________.

Question 55

The ________ is the entire set of proteins expressed by a genome.

Question 56

Recognition sites of restriction enzymes are ________.

Question 57

You are given two samples of DNA,one from Clostridium perfringens and the other from Mycobacterium tuberculosis.Unfortunately,the labels on the tubes of DNA were accidently removed,and you do not know which DNA sample belongs to which organism.As you were doing some work with Escherichia coli in the lab,you also have some of its DNA available as well.The %G+C values for each of the organisms is known (C.perfringens,27%; M.tuberculosis,67%; E.coli,50%).Based upon this information,how could you quickly determine the source of the DNA for your two samples?

Question 58

Two common transposable elements associated with interspersed repeated DNA are ________ and ________.