Question
Download Solution PDFThe segments of the linear double helix of DNA are colled twice around a solid cylinder of eight histone protein molecules, forming a
Answer (Detailed Solution Below)
Detailed Solution
Download Solution PDFThe correct answer is nucleosome
Concept:
- DNA packaging is an essential process in the cell nucleus to fit the extremely long DNA molecules into the small nuclear space.
- The fundamental unit of DNA packaging in eukaryotes is the nucleosome.
- Nucleosomes are formed by the wrapping of DNA around histone proteins, which helps in the efficient organization and regulation of DNA.
Explanation:
- Nucleosome: The nucleosome is the basic unit of DNA packaging in eukaryotic cells. It consists of a segment of DNA wound around a core of eight histone proteins. This structure compacts the DNA and helps in organizing it within the nucleus. Each nucleosome is composed of approximately 147 base pairs of DNA wrapped around a histone octamer, which includes two copies each of histones H2A, H2B, H3, and H4.
- Nuclear envelope: The nuclear envelope is a double membrane that surrounds the nucleus in eukaryotic cells. It separates the contents of the nucleus from the cytoplasm and contains nuclear pores that regulate the passage of molecules between the nucleus and cytoplasm. It is not involved in the packaging of DNA.
- Ribosome: Ribosomes are molecular machines responsible for synthesizing proteins by translating messenger RNA (mRNA) into polypeptides. They are found in the cytoplasm and on the rough endoplasmic reticulum. They do not play a role in DNA packaging.
- Nucleolus: The nucleolus is a region within the nucleus where ribosomal RNA (rRNA) is synthesized and ribosome assembly begins. It is not involved in the packaging of DNA.
- Nuclear pore: Nuclear pores are large protein complexes that span the nuclear envelope. They allow the transport of molecules between the nucleus and the cytoplasm. They are not involved in DNA packaging.
Last updated on May 30, 2025
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