Deck 7: Genes Genomics and Chromosomes

Question 1

Which of the following organisms has the greatest amount of DNA per cell?

A)chicken
B)fruit fly
C)tulip
D)human

Answer 1

C

Question 2

What is the underlying mechanism behind why gene mutations that lead to Huntington's disease act as dominant mutations?

Answer 2

The mutations that lead to Huntington's disease are examples of expanded microsatellite repeats.In the case of the gene responsible for Huntington's disease,there is a triplet CAG repeat in the first exon.Expansion of this repeat results in synthesis of long stretches of polyglutamine.Over time,the protein products that contain long stretches of polyglutamine aggregate.Protein aggregation leads to neuronal cell death,which in turn gives rise to the symptoms of Huntington's disease.These microsatellite mutations are dominant because the presence of aggregated proteins causes symptoms,even though some normal proteins are produced from the normal allele.

Question 3

All the following statements about complex transcription units are true except:

A)They can have multiple poly(A)sites.
B)They can generate multiple mRNAs.
C)They can generate multiple polypeptides.
D)They are common in bacteria.

Answer 3

D

Question 4

What is the advantage of complex transcription units over simple transcription units?

Question 5

Give a functional definition of a gene.

Question 6

Drosophila is considered a model system because it is quite easy to create transgenic lines harboring a variety of different genes.As a Drosophila geneticist,which one of the following is a DNA transposon that you would exploit to create a transgenic line?

A)copia element
B)N element
C)P element
D)Ty element

Question 7

Blood samples were retrieved from a crime scene,and three suspects were arrested on suspicion of committing the crime.Which of the following techniques could be used to identify the suspect(s)responsible for crime?

A)DNA fingerprinting
B)polymerase chain reaction
C)in situ hybridization
D)DNA fingerprinting and polymerase chain reaction

Question 8

Which of the following is a typical feature of prokaryotic genes?

A)polycistronic messenger RNAs
B)complex transcription units
C)introns
D)a and c

Question 9

Which of the following is not a mobile DNA element?

A)transposon
B)long terminal repeats (LTR)
C)long interspersed elements (LINES)
D)insertion sequence (IS)elements

Question 10

Short micro RNAs (miRNAs)

A)code for proteins.
B)are common in bacteria but not eukaryotes.
C)are involved in regulation of gene expression.
D)have no known function.

Question 11

In eukaryotes,tandemly repeated genes encode

A)rRNAs.
B)cytoskeletal proteins.
C)β-globin.
D)all of the above

Question 12

Which of the following mobile elements is a retrotransposon?

A)yeast Ty element
B)bacterial IS sequence
C)Drosophila P element
D)maize activator (Ac)element

Question 13

The chicken lysozyme gene is considered to be a solitary gene because

A)it contains no introns.
B)it is not present on a chromosome.
C)it is represented only once in the haploid genome.
D)none of the above

Question 14

Describe the proposed mechanism discussed in this chapter for the origin of gene families.

Question 15

All the following steps are performed by the enzyme transposase during transposition of bacterial insertion sequences except

A)excision of the IS element from the donor DNA molecule.
B)introduction of staggered cuts into the target DNA molecule.
C)ligation of the IS element to the target DNA.
D)synthesis of DNA to fill in the single-stranded gaps.

Question 16

After a diagnostic sequencing analysis of an individual's DNA,you find that this person has a number of microsatellite triplet repeats within a region of their huntingtin gene.Specifically,these CAG repeats code for long stretches of:

A)glycines.
B)prolines.
C)glutamines.
D)stop codons.

Question 17

All the following statements about microsatellite DNA are true except:

A)It consists of a repeat length of 1-13 base pairs.
B)It can cause neurological diseases such as myotonic dystrophy.
C)It can occur within transcription units.
D)all of the above

Question 18

Describe the general organization of protein coding genes in the yeast and human genomes.

Question 19

Which of the following classes of repetitive DNA is most abundant in the human genome?

A)simple-sequence DNA
B)non-LTR transposons
C)LTR transposons
D)DNA transposons

Question 20

Which one of the following regarding pseudogenes is NOT true?

A)They are present in the eukaryotic genome.
B)They encode miRNAs.
C)They mark the region of gene duplications.
D)They always encode functional products.

Question 21

Describe the two major pathways for transposition of mobile elements.

Question 22

All of the following can be found in chromatin except

A)DNA.
B)histones.
C)RNA.
D)transcription factors.

Question 23

Which of the following terms describes the phenomenon of genes occurring in the same order on a chromosome in two different species?

A)heterochrony
B)neoteny
C)synteny
D)phylogeny

Question 24

Mobile DNA elements likely contributed to the evolution of higher organisms by the

A)generation of gene families by gene duplication.
B)creation of new genes by exon shuffling.
C)formation of more complex regulatory regions.
D)all of the above

Question 25

How many genes are estimated to be in the human genome?

A)21,000
B)35,000
C)75,000
D)100,000

Question 26

To examine the folding and compaction of chromatin during mitosis,you will need to isolate and stain chromosomes at a particular stage using a special spreading preparation technique.For the best analysis,the chromosomes must be at which one of the following stages?

A)metaphase
B)interphase
C)telophase
D)anaphase

Question 27

Which of the following pairs of proteins are considered to be paralogous?

A)yeast α-tubulin and yeast β-tubulin
B)yeast α-tubulin and worm α-tubulin
C)fly β-tubulin and human β-tubulin
D)worm β-tubulin and human α-tubulin

Question 28

There are five major types of histone proteins,but only four of them are considered as core histones.Which one of the following is NOT considered a core histone protein?

A)H1
B)H2B
C)H3
D)H4

Question 29

Which of the following is an algorithm designed to compare the sequence of a newly identified protein with sequences already stored in the GenBank database?

A)LINES
B)BLAST
C)HATs
D)3C

Question 30

Open reading frame (ORF)analysis is not effective in identifying genes in higher eukaryotes because of the presence of

A)promoters.
B)enhancers.
C)introns.
D)repetitious DNA.

Question 31

"3C" or chromosome conformation capture methods,used to determine the three-dimensional spatial organization of chromatin within nuclei of interphase cells,rely on a series of steps where the end result is the sequence analysis of purified DNA fragments.Which one of the following presents the correct order of steps you as an investigator need to follow in a 3C method strategy?

A)shear DNA to 200-600 bp;cross-link proteins and DNA with formaldehyde
B)ligate linkers marked with biotin onto DNA fragments;dilute and ligate the fragments
C)cross-link streptavidin to DNA;purify and shear biotin-labeled fragments
D)none of the above

Question 32

You are studying the regulation of a group of genes and have determined that the full activation of transcription of these genes occurs when histone acetyl transferases have made post-translational modifications specifically to which one of the following amino acids?

A)glycine
B)glutamine
C)lysine
D)proline

Question 33

Which of the following terms describes when a chromosome is replicated everywhere except the telomeres and centromere,but the daughter chromosomes do not separate?

A)hybridization
B)polytenization
C)polymerization
D)heterochromatization

Question 34

All the following statements are true about a nucleosome except:

A)It contains an octamer core of histones.
B It is about 10 nm in diameter.
C)It is the "string" of the "beads-on-a-string" appearance.
D)It contains approximately 150 base pairs of DNA.

Question 35

Which of the following is NOT a functional element required for any eukaryotic chromosome to replicate and segregate correctly?

A)replication origin
B)centromere
C)kinetochore
D)telomeres

Question 36

Histone modifications play integral roles in chromatin condensation and function.Which of the following is NOT considered to be a histone modification?

A)acetylation
B)methylation
C)phosphorylation
D)prenylation

Question 37

DNA that is transcriptionally active

A)is more susceptible to DNase I digestion.
B)is tightly packed into a solenoid arrangement.
C)contains nonacetylated histones.
D)is more condensed than nontranscribed DNA.

Question 38

Which of the following lines of evidence is indicative of the presence of a gene in an unknown DNA sequence?

A)alignment to a partial cDNA sequence
B)sequence similarity to genes of other organisms
C)ORF consistent with the rules for exon and intron sequences
D)all of the above

Question 39

The DNA and protein sequences of the α-tubulin genes in humans and in fish are similar,and because each arose due to speciation,these genes would be considered:

A)homologous.
B)orthologous.
C)paralogous.
D)autologous.

Question 40

SINES (short interspersed elements)

A)are approximately 300 base pairs long.
B)are LTRs containing retrotransposons.
C)are present in over 1 million copies in the human genome.
D)a and c

Question 41

Telomeres

A)consist of repetitive sequences with high G content.
B)are a few hundred base-pairs long in vertebrates.
C)have specific proteins bound at the DNA ends.
D)a and c

Question 42

Which of the following statement(s)is (are)true of a eukaryotic chromosome?

A)It is a linear structure.
B)It consists of a single DNA molecule.
C)It can contain greater than a billion base pairs of DNA.
D)all of the above

Question 43

The karyotype for any particular species is characterized by

A)the number of metaphase chromosomes.
B)the size and shape of the metaphase chromosomes.
C)the banding pattern of the metaphase chromosomes.
D)all of the above

Question 44

Why is there a need for a specialized structure at the ends of eukaryotic chromosomes and for the enzyme telomerase?

Question 45

Describe how modification of histone tails can control chromatin condensation.

Question 46

In mammals,X-chromosome inactivation
a.occurs in half the diploid cells of the adult female.
b.results from the ionization of the X-chromosome.
c.is considered an epigenetic event.
d.b and c
Ans.c

Question 47

Chromosome painting involves

A)staining chromosomes with Giemsa reagent.
B)hybridizing fluorescent probes to chromosomes.
C)hybridizing radioactive probes to chromosomes.
D)a and b

Question 48

All the following statements about heterochromatin except:

A)It is a dark-staining area of a chromosome.
B)It is usually transcriptionally active.
C)It is often simple sequences of DNA.
D)It is a region of condensed chromatin.