STP Genomics & Molecular Biology

Question 1

Which enzyme is primarily responsible for synthesizing new DNA strands during replication in eukaryotes?

Accepted Answer

DNA Polymerase δ

Answer

DNA Polymerase δ is the main replicative polymerase responsible for synthesizing the lagging and leading strands during eukaryotic DNA replication.

Question 2

What is the primary purpose of the polymerase chain reaction (PCR) in a clinical laboratory setting?

Accepted Answer

To amplify a specific DNA or RNA target for detection or analysis

Answer

PCR amplifies a defined region of nucleic acid exponentially, enabling detection or downstream analysis even from minute sample quantities.

Question 3

A single nucleotide polymorphism (SNP) is best described as:

Accepted Answer

A variation in a single base pair at a specific locus occurring in ≥1% of the population

Answer

SNPs are the most common form of genetic variation, defined as a single base change at a given genomic position present in at least 1% of the population.

Question 4

In gel electrophoresis of DNA, smaller fragments migrate:

Accepted Answer

Faster and further from the wells than larger fragments

Answer

The negatively charged DNA migrates towards the positive electrode, and smaller fragments experience less resistance in the gel matrix, moving faster and further.

Question 5

Which molecular technique uses sequence-specific probes to detect target DNA within intact chromosomal preparations?

Accepted Answer

Fluorescence in situ hybridisation (FISH)

Answer

FISH uses fluorescently labelled probes that hybridise to complementary sequences on chromosomes, allowing visual detection of specific loci or structural rearrangements.

(STP) Scientist Training Programme Practice Test

(STP) Scientist Training Programme Practice Test

STP Genomics & Molecular Biology