A eukaryotic chromosome is made up of:
A) DNA only
B) protein and nucleic acid
C) centromeres and centrioles
D) loops of naked DNA
E) DNA and RNA only
The correct answer and explanation is:
The correct answer is B) protein and nucleic acid.
A eukaryotic chromosome consists of both DNA and protein. The primary component of a chromosome is DNA, which carries the genetic information essential for cell functions and inheritance. This DNA is organized and compacted by proteins, primarily histones, which help in the folding and packaging of the genetic material into a dense structure. The resulting structure is known as chromatin.
In eukaryotic cells, the DNA is wrapped around histone proteins, forming nucleosomes. These nucleosomes resemble beads on a string, with the DNA wrapped around the histone core. The chromatin fibers then fold and condense further to form the visible chromosomes during cell division, ensuring that the genetic material is accurately distributed to daughter cells.
Histones are the main proteins involved in this process, but there are other proteins that also play important roles in regulating gene expression and maintaining chromosome structure. Non-histone proteins assist in functions like DNA replication, repair, and transcription. In addition to histones, other structural proteins help in maintaining the overall shape and stability of the chromosome, while also participating in the segregation of chromosomes during cell division.
Other answer choices like A) DNA only, D) loops of naked DNA, and E) DNA and RNA only are incorrect because chromosomes are not composed solely of DNA or RNA alone. C) centromeres and centrioles is not a correct option either because centromeres are part of the chromosome structure, while centrioles are involved in organizing the spindle fibers during cell division, but are not components of the chromosome itself.
Thus, chromosomes are a complex combination of DNA and proteins, working together to store genetic information and enable cell processes.