Molecular Chapter 7 - Chromosomal Structure and Chromosomal Mutations

1. 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

ANS: B

OBJ: 7.1

2. 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.

ANS: B

OBJ: 7.1

3. A translocation is which type of mutation?

A. Gene

B. Genome

C. Chromosome

D. Nucleotide

ANS: C

OBJ: 7.2

4. 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 the effect on phenotype

D. Associations with other genetic events

ANS: A

OBJ: 7.1

5. Down syndrome is caused by an extra copy of chromosome 21, which is what kind of genetic event?

A. Gene mutation

B. Chromosome mutation

C. Genome mutation

D. Point mutation

ANS: C

OBJ: 7.2

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

A. Euploid

B. Diploid

C. Triploid

D. Tetraploid

ANS: C

OBJ: 7.2

7. 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

ANS: B

OBJ: 7.3

8. 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)

ANS: B

OBJ: 7.3

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

A. Kinetochores

B. Telomeres

C. Centromeres

D. Histones

ANS: B

OBJ: 7.3

10. A chromosome that has the centromere in the center of the chromosome is called

A. acrocentric.

B. telocentric.

C. metacentric.

D. holocentric.

ANS: C

OBJ: 7.4

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

A. o

B. p

C. q

D. r

ANS: B

OBJ: 7.4

12. 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. Genocentric

D. Acrocentric

ANS: D

OBJ: 7.4

13. 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

ANS: A

OBJ: 7.4

14. Giemsa dye stains compacted chromosomes at which location?

A. G bands

B. Centromeres

C. CpG sites

D. Euchromatin

ANS: A

OBJ: 7.3

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

A. Whole chromosome

B. Heterochromatin

C. Euchromatin

D. Centromere

ANS: D

OBJ: 7.3

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

A. Heterochromatin

B. Homochromatin

C. Euchromatin

D. Interchromatin

ANS: C

OBJ: 7.3

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

A. Prophase

B. Metaphase

C. Anaphase

D. Telophase

ANS: B

OBJ: 7.6

18. How is high-resolution karyotype 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.

ANS: D

OBJ: 7.6

19. 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

ANS: D

OBJ: 7.3

20. Colcemid is used in the procedure of preparing a chromosome spread for karyotype analysis for which purpose?

A. To spread the chromosomes out within the cell

B. To inhibit microtubule formation

C. To induce cells to enter mitosis

D. To fix cells to the slide prior to staining

ANS: B

OBJ: 7.6

21. An exchange of chromosomal material between chromosomes is called a(n)

A. deletion.

B. inversion.

C. insertion.

D. translocation.

ANS: D

OBJ: 7.5

22. 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.

ANS: C

OBJ: 7.5

23. 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

ANS: B

OBJ: 7.6

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

A. Microdeletion

B. Reciprocal translocation

C. Aneuploidy

D. Polyploidy

ANS: A

OBJ: 7.7

25. 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 syndrome.

C. abnormal; the patient lacks a copy of chromosome 21.

D. abnormal; the patient has a Philadelphia chromosome.

ANS: A

OBJ: 7.8

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

A. The examination of 20 spreads in interphase FISH has increased sensitivity.

B. Interphase FISH allows identification of mutations anywhere in the chromosome.

C. Interphase FISH allows identification of all chromosomes.

D. Results are available faster in interphase FISH procedures.

ANS: D

OBJ: 7.8

27. An interphase FISH procedure 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, and a probe for the myc gene on chromosome 8 gives two distinct signals. 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.

ANS: A

OBJ: 7.8

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

A. size.

B. degree of staining.

C. fluorescent color.

D. position.

ANS: C

OBJ: 7.8

29. 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

ANS: A

OBJ: 7.10

30. Before its conversion to a microarray technique, comparative genome hybridization (CGH) was performed by hybridizing labeled DNA to what support?

A. Immobilized PCR products

B. Normal chromosome spread

C. Nitrocellulose membrane

D. Agarose gel

ANS: B

OBJ: 7.10

Question 1

What is the normal human karyotype notation for a typical male?

• Option A

  46,XY, del(7)

• Option B

  46,XX

• Option C

  46,XY

• Option D

  47,XYY

C

Which event would be revealed by metaphase FISH but not as easily by interphase FISH?

• Option A

  Detecting gene expression levels

• Option B

  Detecting sub-telomeric deletions

• Option C

  Observing structural changes in metaphase chromosomes

• Option D

  Visualizing telomere length on interphase cells

c

Question 3

What is indicated by a translocation in chromosomes?

• Option A

  Inversion within a single chromosome

• Option B

  Duplication of a single gene

• Option C

  Exchange of material between chromosomes

• Option D

  Deletion of a gene

c

Question 4

Which structure is stained to identify banding patterns in G-banded karyotypes?

• Option A

  Lipids

• Option B

  Proteins

• Option C

  RNA transcripts

• Option D

  Chromosomes

d

Question 5

Which feature marks the end of a chromosome?

• Option A

  Telomere

• Option B

  Centromere

• Option C

  Kinetochore

• Option D

  Chromatid

a

Match the molecular biology concepts with their correct descriptions or terms (each option used once):

1. enzyme that copies DNA during PCR

2. DNA strand that separates by heat in PCR

3. DNA segment that is amplified during PCR

4. site where primers bind to begin DNA synthesis

Choices:

a. Denatureation
b. ligase
c. Taq polymerase
d. primer annealing
e. target amplicon

1. c

2. a

3. e

4. d

What is the long end of a chromosome arm called?

• Option A

  q arm

• Option B

  Centromere

• Option C

  Telomere

• Option D

  p arm

a

Which FISH probe is used to detect gene rearrangements, deletions, and amplifications?

• Option A

  Whole-chromosome painting (WCP)

• Option B

  Centromere probes (CEP)

• Option C

  Unique DNA sequence probes (LSI)

• Option D

  Telomere probes (TELs)

c

Which description best fits a polymorphism in a population?

• Option A

  A change in chromosome number

• Option B

  Two or more genetically determined phenotypes are common in the population

• Option C

  A temporary genetic change

• Option D

  A single rare mutation

b

Question 10

In a karyotype, what does the centromere define?

• Option A

  The site of DNA replication

• Option B

  The telomere end of the chromosome

• Option C

  Where genes are transcribed

• Option D

  The constriction that creates the two chromosome arms

d