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

Question 1

Interspersed repeat DNA

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

Answer 1

E

Question 2

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

Answer 2

E

Question 3

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

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

Answer 3

D

Question 4

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

Question 5

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

Question 6

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

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

Question 7

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

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

Question 8

DNA is different from RNA in that

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

Question 9

Restriction enzymes typically recognize

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

Question 10

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

Question 11

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

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

Question 12

The nucleolus

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

Question 13

In experiments designed as those of Hershey and Chase (1952), 35S was added to 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 nucleic acid of the new virions
B)in the bacterial DNA
C)in the protein coat of the new virions
D)in the phage ghosts
E)in the bacterial matrix proteins

Question 14

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

Question 15

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

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

Question 16

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

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

Question 17

Which of the following statements regarding the Watson- Crick model of DNA is NOT accurate?

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

Question 18

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

Question 19

The nuclear membrane functions as a

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

Question 20

With regard to DNA packaging, prokaryotic chromosomes

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

Question 21

Using the Sanger method of DNA sequencing, results in the figure below are obtained following gel electrophoresis of the DNA fragments. A total of 21 nucleotides has been sequenced. What is the sequence of these nucleotides?

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

Question 22

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

Question 23

An example of a purine is

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

Question 24

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

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

Question 25

Which of the following shows Chargaff's equivalence?

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

Question 26

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

Question 27

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

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

Question 28

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

Question 29

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

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

Question 30

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

Question 31

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

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

Question 32

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

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

Question 33

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

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

Question 34

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