AMT Molecular Diagnostics Technologist (MDT)
Certification Exam – Newest Practice Questions &
Answers Complete Study Guide for the MDT Exam
|Instant PDF Download
About the AMT MDT Exam
The Molecular Diagnostics Technologist (MDT) certification from American
Medical Technologists (AMT) validates entry-level competency in molecular
diagnostic testing. The exam is designed for laboratory professionals specializing
in high-complexity molecular pathology.
Content Domains & Weighting:
Domain Questions Weight
I. General Laboratory 36 18%
II. General Molecular Diagnostics Theory 40 20%
III. Molecular Laboratory Procedures 20 10%
IV. Diagnostic Methods 104 52%
Section 1: Molecular Biology Foundations (Questions 1-30)
1. Which of the following nitrogenous bases is a purine found in both DNA and
RNA?
A) Cytosine
B) Thymine
C) Guanine
D) Uracil
Answer: C
, Guanine and adenine are purines (double-ring structures) present in both DNA
and RNA. Cytosine is a pyrimidine found in both; thymine is unique to DNA; uracil
is unique to RNA.
2. In a DNA molecule, the phosphodiester bond links which two components?
A) Two nitrogenous bases across the double helix
B) The 5' phosphate group of one nucleotide to the 3' hydroxyl group of another
C) The sugar molecule to the nitrogenous base
D) The amino acid sequence to the mRNA codon
Answer: B
Phosphodiester bonds form the DNA backbone by linking the 5' phosphate group
of one nucleotide to the 3' hydroxyl group of the adjacent nucleotide.
3. During DNA replication, which enzyme is responsible for unwinding the
double helix at the replication fork?
A) Helicase
B) Primase
C) Ligase
D) Topoisomerase
Answer: A
Helicase unwinds the double-stranded DNA at the replication fork, separating the
two strands for replication to proceed.
4. DNA synthesis always proceeds in which direction?
A) 3' to 5'
B) 5' to 3'
C) 2' to 5'
D) 3' to 3'
Answer: B
DNA polymerases can only add nucleotides to the 3' hydroxyl group of a growing
DNA strand, meaning synthesis always proceeds in the 5' to 3' direction.
,5. Which RNA species is responsible for carrying amino acids to the ribosome
during translation?
A) mRNA
B) snRNA
C) tRNA
D) rRNA
Answer: C
Transfer RNA (tRNA) molecules act as adapters, carrying specific amino acids to
the ribosome and matching them to the mRNA sequence via anticodons.
6. Which enzyme is responsible for synthesizing cDNA from an RNA template in
RT-PCR?
A) DNA Ligase
B) RNA Polymerase II
C) Reverse Transcriptase
D) Taq Polymerase
Answer: C
Reverse transcriptase is an RNA-dependent DNA polymerase that creates
complementary DNA (cDNA) from an RNA template.
7. A "nonsense" mutation results in which of the following?
A) Replacement of one amino acid with another
B) Premature termination of the polypeptide chain
C) A shift in the reading frame of the gene
D) No change in the amino acid sequence
Answer: B
A nonsense mutation changes an amino acid codon into a stop codon (UAG, UAA,
or UGA), leading to a truncated, nonfunctional protein.
8. Which type of mutation results in a premature stop codon in the mRNA
sequence?
, A) Missense mutation
B) Silent mutation
C) Nonsense mutation
D) Frameshift mutation
Answer: C
A nonsense mutation is a point mutation that changes an amino acid-coding
codon into a stop codon, leading to a truncated protein.
9. Which of the following represents a "Stop Codon" in the genetic code?
A) AUG
B) UGG
C) UAA
D) GGG
Answer: C
UAA is one of three stop codons (UAA, UAG, UGA) that signal termination of
protein synthesis.
10. Which of the following nitrogenous bases are classified as Purines?
A) Cytosine and Thymine
B) Adenine and Guanine
C) Uracil and Cytosine
D) Thymine and Uracil
Answer: B
Adenine and guanine are purines characterized by a double-ring structure.
Cytosine, thymine, and uracil are pyrimidines (single-ring structures).
11. A "frameshift" mutation is caused by:
A) Substitution of one base for another
B) Insertion or deletion of nucleotides not in multiples of three
C) Change of one amino acid to another
D) Replacement of a codon with a stop codon
Answer: B
Certification Exam – Newest Practice Questions &
Answers Complete Study Guide for the MDT Exam
|Instant PDF Download
About the AMT MDT Exam
The Molecular Diagnostics Technologist (MDT) certification from American
Medical Technologists (AMT) validates entry-level competency in molecular
diagnostic testing. The exam is designed for laboratory professionals specializing
in high-complexity molecular pathology.
Content Domains & Weighting:
Domain Questions Weight
I. General Laboratory 36 18%
II. General Molecular Diagnostics Theory 40 20%
III. Molecular Laboratory Procedures 20 10%
IV. Diagnostic Methods 104 52%
Section 1: Molecular Biology Foundations (Questions 1-30)
1. Which of the following nitrogenous bases is a purine found in both DNA and
RNA?
A) Cytosine
B) Thymine
C) Guanine
D) Uracil
Answer: C
, Guanine and adenine are purines (double-ring structures) present in both DNA
and RNA. Cytosine is a pyrimidine found in both; thymine is unique to DNA; uracil
is unique to RNA.
2. In a DNA molecule, the phosphodiester bond links which two components?
A) Two nitrogenous bases across the double helix
B) The 5' phosphate group of one nucleotide to the 3' hydroxyl group of another
C) The sugar molecule to the nitrogenous base
D) The amino acid sequence to the mRNA codon
Answer: B
Phosphodiester bonds form the DNA backbone by linking the 5' phosphate group
of one nucleotide to the 3' hydroxyl group of the adjacent nucleotide.
3. During DNA replication, which enzyme is responsible for unwinding the
double helix at the replication fork?
A) Helicase
B) Primase
C) Ligase
D) Topoisomerase
Answer: A
Helicase unwinds the double-stranded DNA at the replication fork, separating the
two strands for replication to proceed.
4. DNA synthesis always proceeds in which direction?
A) 3' to 5'
B) 5' to 3'
C) 2' to 5'
D) 3' to 3'
Answer: B
DNA polymerases can only add nucleotides to the 3' hydroxyl group of a growing
DNA strand, meaning synthesis always proceeds in the 5' to 3' direction.
,5. Which RNA species is responsible for carrying amino acids to the ribosome
during translation?
A) mRNA
B) snRNA
C) tRNA
D) rRNA
Answer: C
Transfer RNA (tRNA) molecules act as adapters, carrying specific amino acids to
the ribosome and matching them to the mRNA sequence via anticodons.
6. Which enzyme is responsible for synthesizing cDNA from an RNA template in
RT-PCR?
A) DNA Ligase
B) RNA Polymerase II
C) Reverse Transcriptase
D) Taq Polymerase
Answer: C
Reverse transcriptase is an RNA-dependent DNA polymerase that creates
complementary DNA (cDNA) from an RNA template.
7. A "nonsense" mutation results in which of the following?
A) Replacement of one amino acid with another
B) Premature termination of the polypeptide chain
C) A shift in the reading frame of the gene
D) No change in the amino acid sequence
Answer: B
A nonsense mutation changes an amino acid codon into a stop codon (UAG, UAA,
or UGA), leading to a truncated, nonfunctional protein.
8. Which type of mutation results in a premature stop codon in the mRNA
sequence?
, A) Missense mutation
B) Silent mutation
C) Nonsense mutation
D) Frameshift mutation
Answer: C
A nonsense mutation is a point mutation that changes an amino acid-coding
codon into a stop codon, leading to a truncated protein.
9. Which of the following represents a "Stop Codon" in the genetic code?
A) AUG
B) UGG
C) UAA
D) GGG
Answer: C
UAA is one of three stop codons (UAA, UAG, UGA) that signal termination of
protein synthesis.
10. Which of the following nitrogenous bases are classified as Purines?
A) Cytosine and Thymine
B) Adenine and Guanine
C) Uracil and Cytosine
D) Thymine and Uracil
Answer: B
Adenine and guanine are purines characterized by a double-ring structure.
Cytosine, thymine, and uracil are pyrimidines (single-ring structures).
11. A "frameshift" mutation is caused by:
A) Substitution of one base for another
B) Insertion or deletion of nucleotides not in multiples of three
C) Change of one amino acid to another
D) Replacement of a codon with a stop codon
Answer: B
