Question 62 Linear DNA in the human genome is packaged at several levels. Which of the following represents the levels from least packaged to most packaged? (A) Nucleosomes, DNA strand, chromosomes (B) DNA strand, nucleosomes, chromosomes (C) DNA strand, chromosomes, nucleosomes (D) Chromosomes, nucleosomes, DNA strand
Answer (1)
The order of packaging of DNA in the human genome from least packaged to most packaged is as follows:
DNA Strand: This is the simplest and least packaged form of DNA. It is a long, linear molecule that consists of two strands coiled around each other, forming a double helix. The DNA carries genetic information vital for the inheritance of traits.
Nucleosomes: As DNA starts to fold into higher levels of packaging, it wraps around proteins called histones to form nucleosomes. A nucleosome consists of a segment of DNA wound around a core of histone proteins, resembling 'beads on a string'. This is the first level of DNA compaction after the raw DNA strand and helps in organizing DNA into the cell nucleus.
Chromosomes: This is the most compact form of DNA packaging. Chromosomes are highly condensed, tightly coiled structures that form when DNA is further wrapped and folded around histones and other proteins. Chromosomes are only visible during cell division when DNA is organized in this compact form to ensure its even distribution into daughter cells.
Thus, the correct sequence from least packaged to most packaged is: DNA strand, nucleosomes, chromosomes.
Therefore, the correct answer is option (B) DNA strand, nucleosomes, chromosomes.
Understanding the hierarchical organization of DNA is crucial for grasping how genetic material is organized within the cell, facilitating processes such as DNA replication and gene expression.
