Molecular biology and genetics, Quizzes of Molecular biology

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1. Expansion of trinucleotide repeats is the type of

A. Gene mutation

B. Chromosomal mutation

C. None of them

2. How would a shift in the reading frame likely alter the resulting protein?

a. The protein would be greatly altered because multiple amino acids would be miscoded.

b. The protein would be only slightly altered because a single amino acid would be

miscoded.a

c. The protein would be not be altered because the reading frame does not affect the

resulting protein.

d. Any alteration to the reading frame would prevent the protein from being formed.

3. mark the correct statement regarding transition mutations

A. one pyrimidine base replace another pyrimidine

B. the ratio of transitions to transversions is approximately 2 : 1.

C. Transition mutations is the type of point mutation

D. All correct

4. Which of the following mutations results in a non-functional protein because a stop codon appeared too early in the mRNA sequence?

A. Missence

B. Nonesence

C. Silent

D. Frameshift

5. Which type of mutation results in the sickle-cell disease phenotype? A. Non-conservative missense mutation B. Conservative mutation C. Frameshift mutation D. Codon deletion

6.Consider the following normal sequence of genes: a b c d e f g h. The sequence a b f e d c g h

represents a (an)

a. deletion.

b. duplication.

c. inversion.

d. Translocation

7. A non-conservative mutation is one in which: A. The new amino acid has different biochemical properties than the original B. A frameshift has occurred, causing production of a new amino acid C. A large segment of DNA is deleted D. No effect results in the protein

8. A mutation always causes a mutant phenotype

A. True

B. False

9. Which of the following can not cause mutations?

A. Chemical mutagens found in the environment B. Transcription errors by RNA polymerase C. Radiation from the sun D. Products produced by cells involved in chronic inflammation E. None of them F. All of them

10.Changes in DNA sequences during replication can lead to the following

A. missence mutation

B. nonsense mutation

C. aneuploidy

D. all of them

E. A and B

11. A silent mutation is highly unlikely to affect protein because:

A. Multiple codons can code for the same amino acid B. The silent mutation substitutes the same type of amino acid C. The dominant allele can compensate for the silent mutation D. The silent mutation does not cause a frameshift

12. c A. Missense mutations B. Displacement of RNA polymerase C. Constitutive expression of oncogenes D. Deformation of the DNA molecule

13. Which of the following represents a transition?

A. G –A

B. T-A

C. G-C

D. A-T

14.The Mc1r gene encodes the melanocortin-1-receptor protein (MC1R). MC1R is found in pigment-producing cells and helps regulate skin and hair color in mammals. An alignment between six amino acids of the wild type MC1R protein and a mutant form of the protein is shown in the following table. The mutant form of the MC1R protein is encoded by a version of the Mc1r gene with a mutation in its coding sequence. Based on the information in the table, which of the following best describes the mutation in the MC1R gene? A. a single base-pair substitution in the 20th codon of the Mc1r gene B. a single base-pair deletion in the 20th codon of the Mc1r gene C. a three-nucleotide deletion of the 20th codon of the Mc1r gene D. a silent mutation in the 20th codon of the Mc1r gene

15. inversion result in A. The formation of many copies of a specific region of the affected chromosome B. The breakage and movement of chromosome fragments C. More than one copy of each gene on a chromosome D. A genetic change that involves the loss or gain of entire chromosomes E. Segments of DNA being released from a chromosome then re-inserted in the opposite orientation