Deck 8: Chromosomal Structure and Chromosomal Mutations

Question 1

Which of the following types of chromatin are open and actively involved in gene expression (transcription)?

A) Heterochromatin
B) Homochromatin
C) Euchromatin
D) Interchromatin

Answer 1

Euchromatin

Question 2

Colcemid is used in the procedure of preparing a chromosome spread for karyotype analysis to do which of the following?

A) Spread the chromosomes out within the cell
B) Inhibit microtubule formation
C) Induce cells to enter mitosis
D) Fix cells to the slide prior to staining

Answer 2

Inhibit microtubule formation

Question 3

When chromosomes are stained with Giemsa, the resulting bands are called:

A) G bands
B) Q bands
C) R bands
D) C bands

Answer 3

G bands

Question 4

Which of the following is involved in connecting the centromere to the spindles during chromosome segregation in mitosis?

A) Kinetochore
B) Euchromatin
C) Histone protein H1
D) Heterochromatin

Question 5

A chromosome that has the centromere in the center of the chromosome is called:

A) Acrocentric
B) Telocentric
C) Metacentric
D) Holocentric

Question 6

What is a phenotype?

A) The structure of a gene
B) A trait resulting from gene transcription and translation
C) The nucleotide sequence responsible for a genotype
D) A change in the gene structure

Question 7

The short arm of the chromosome is designated as which of the following?

A) o
B) p
C) q
D) r

Question 8

A change in DNA sequence that is present in at least 1% to 2% of the population is called a(n):

A) Phenotype
B) Polymorphism
C) Aneuploid
D) Mutation

Question 9

Chromosomes are divided into different parts, and locations are denoted by numbers corresponding to the different parts in which of the following orders?

A) Sub-band, band, chromosome, region
B) Region, band, sub-band, chromosome
C) Band, chromosome, region, sub-band
D) Chromosome, region, band, sub-band

Question 10

How is high-resolution banding achieved?

A) Increase the concentration of Giemsa.
B) Stain the chromosomes longer.
C) Stain the chromosomes at low temperatures.
D) Stain the chromosomes before maximal condensation.

Question 11

Down's syndrome is caused when an extra copy of chromosome 21 is created, which is what kind of genetic event?

A) Gene mutation
B) Chromosome mutation
C) Genome mutation
D) Euploidy

Question 12

A reciprocal translocation is which type of mutation?

A) Gene
B) Genome
C) Chromosome
D) Nucleotide

Question 13

What are the structures found only at the ends of human chromosomes?

A) Kinetochores
B) Telomeres
C) Centromeres
D) Histones

Question 14

Examination of chromosomes in karyotypes is performed on chromosomes in what stage of mitosis?

A) Prophase
B) Metaphase
C) Interphase
D) Telophase

Question 15

In a C banding pattern, what part of the chromosome stains?

A) Whole chromosome
B) Heterochromatin
C) Euchromatin
D) Centromere

Question 16

Which is the proper order for the four phases of the cell cycle?

A) G1, S, M, G2
B) G1, S, G2, M
C) G2, S, M, G1
D) M, S, G1, G2

Question 17

A nucleosome consists of DNA and which of the following combinations of histone proteins?

A) 2(H1), 2(H2A), 2(H3), 2(H4)
B) 2(H2A), 2(H2B), 2(H3), 2(H4)
C) 2(H1), 2(H2A), 2(H2B), 2(H4)
D) 2(H2), 2(H3), 2(H4), 2(H5)

Question 18

What is the designation of a cell with three copies of every chromosome?

A) Euploid
B) Diploid
C) Triploid
D) Tetraploid

Question 19

A polymorphism is distinguished from a mutation in what way?

A) Its frequency in a given population
B) The size of the genetic region involved
C) The severity of effect on phenotype
D) Associations with other genetic events

Question 20

Human chromosomes 21 and 22 are described as which of the following with regard to the location of the centromere?

A) Telocentric
B) Holocentric
C) Metacentric
D) Acrocentric

Question 21

Comparative genome hybridization detects which type of genetic abnormalities?

A) Amplifications relative to reference DNA
B) Absolute gene numbers
C) Inversions
D) Amino acid substitutions

Question 22

Before its conversion to a microarray technique, CGH was performed by hybridizing labeled DNA to what support?

A) Immobilized PCR products
B) Normal chromosome spread
C) Nitrocellulose membrane
D) Agarose gel

Question 23

An exchange of genetic material between chromosomes is called a(n):

A) Deletion
B) Inversion
C) Insertion
D) Translocation

Question 24

In spectral karyotyping, each of the 23 chromosomes is distinguished by:

A) Size
B) Degree of staining
C) Fluorescent color
D) Position

Question 25

Interphase FISH has been performed on a patient sample. With a chromosome 8 centromeric (CEP 8) probe, two signals are observed in each spread examined. A probe for the immunoglobulin heavy chain region on chromosome 14 gives two distinct signals per nucleus, and a probe for the myc gene on chromosome 8 gives two distinct signals per nucleus. Which of following interpretations is correct?

A) The patient is normal.
B) The patient has a t(14;8) translocation.
C) The patient has a chromosome 8 deletion.
D) The patient has a chromosome 8 insertion.

Question 26

Which of the following would be most difficult to identify by karyotype?

A) Microdeletion
B) Reciprocal translocation
C) Aneuploidy
D) Polyploidy

Question 27

Which of the following is an advantage of interphase FISH as compared with metaphase FISH?

A) Examination of 20 spreads in interphase FISH has increased sensitivity.
B) One can identify mutations anywhere in the chromosome in interphase FISH.
C) Interphase FISH allows identification of all chromosomes.
D) Results are available faster in interphase FISH procedures than metaphase FISH procedures.

Question 28

A medical laboratory scientist performs fluorescence in situ hybridization (FISH) on interphase chromosomes using a probe to chromosome 21. In all cells examined, two signals were seen. These results are interpreted as:

A) Normal
B) Abnormal; the patient has Down's syndrome
C) Abnormal; the patient is lacking a copy of chromosome 21
D) Abnormal; the patient has a Philadelphia chromosome

Question 29

A chromosome formed when parts of two or more chromosomes are joined to a third normal chromosome is called a(n):

A) Ring chromosome
B) Isochromosome
C) Derivative chromosome
D) Balanced translocation

Question 30

The karyotype of a normal male is designated by which of the following?

A) 46, XX
B) 46, XY
C) 47, XX
D) 47, XY