QCM : Fundamentals of Genetic Structure and Function — 9 questions

Explication

The anti-parallel orientation of DNA strands is crucial because it allows the specific base pairing (A with T, C with G) to occur in a way that enables accurate copying during DNA replication. This structural feature directly influences DNA's ability to replicate reliably, which is fundamental for genetic stability and inheritance.

Explication

DNA Polymerase is the enzyme that synthesizes new DNA strands by adding nucleotides complementary to the template strand in the 5’ to 3’ direction. Helicase unwinds the DNA helix, Ligase joins Okazaki fragments on the lagging strand, and Primase synthesizes RNA primers. Therefore, DNA Polymerase's role is specific to DNA synthesis.

Explication

Kary Mullis is credited with proposing the Polymerase Chain Reaction (PCR) technique in 1983, which revolutionized molecular biology by allowing the exponential amplification of specific DNA sequences. The other scientists listed made significant contributions to biology or medicine but are not associated with PCR.

Explication

Primers are short DNA sequences designed to be complementary to specific regions on the target gene. During PCR, they anneal to these sites, allowing DNA polymerase to extend from the primers and amplify the gene of interest. This targeted approach is fundamental for specific gene amplification. The other options involve unrelated methods: enzymes that cut DNA are not used for amplification, fluorescent dyes bind non-specifically and do not enable specific amplification, and antibodies recognize proteins, not DNA sequences.

Explication

Stem cells are characterized by their ability to divide and differentiate into multiple cell types, making them versatile. Differentiated cells, on the other hand, have specialized functions and are generally limited to their specific cell type. Therefore, the main difference is in their potential to develop into various cell types, with stem cells being pluripotent or multipotent, and differentiated cells being specialized and limited.

Explication

Non-coding DNA mainly plays a regulatory role in the genome by controlling gene expression and transcription. It can include sequences that regulate how genes are transcribed or be transcribed into RNA molecules that do not code for proteins, such as tRNA and rRNA. The other options are incorrect: non-coding DNA does not directly code for proteins, is not solely a template for replication, and does not produce enzymes for unwinding DNA.

Explication

A chromosome deletion involves the removal or loss of a segment of the chromosome, leading to missing genetic information. This is different from inversion (reversal of a segment), translocation (movement of a segment to another chromosome), or duplication (adding an extra copy of a segment).

Explication

Natural selection is defined as the process where beneficial genetic traits become more common in a population over time because they enhance survival and reproductive success, leading to evolution. It is non-random because it favors advantageous traits, unlike random mutation or genetic drift.

Explication

The complete sequencing of the human genome was officially established in 2003, when the Human Genome Project announced the completion of its draft sequence. This milestone marked a major achievement in genomics and phylogenetics, providing a reference genome for further research.