Question

The association of DNA and proteins in a non-dividing eukaryotic cell is called ______.

Answer 1

The association of DNA and proteins in a non-dividing eukaryotic cell is called chromatin.

Explanation

Chromatin is the complex formed by DNA and proteins in the nucleus of eukaryotic cells. It's composed of histone proteins around which the DNA is wrapped, forming nucleosomes. These nucleosomes coil and pack together to condense the genetic material efficiently within the limited space of the nucleus during various cellular processes. In a non-dividing cell, chromatin exists in a less condensed state known as euchromatin, allowing for gene expression and regulation.

The primary proteins involved in chromatin structure are histones, which assist in DNA packaging and play a role in gene regulation by modifying chromatin accessibility. Chemical modifications to histones, such as acetylation, methylation, or phosphorylation, can alter chromatin structure and influence gene expression. This dynamic nature of chromatin allows cells to adapt to changing environmental cues and developmental needs by regulating gene activity without altering the underlying DNA sequence.

During cell division, chromatin undergoes further condensation to form distinct chromosomes, facilitating their segregation into daughter cells. Understanding chromatin structure and its modifications is crucial in various biological processes, including development, disease mechanisms, and epigenetics, as it regulates how genes are turned on or off without changing the DNA sequence itself.

Answer 2

The association of DNA and proteins in a non-dividing eukaryotic cell is known as chromatin. Chromatin is comprised of DNA wrapped around histone proteins to form units called nucleosomes. This complex organization allows efficient packaging of DNA within the nucleus, which is different from the simpler DNA packaging in prokaryotic cells.

Step-by-step explanation:

The association of DNA and proteins in a non-dividing eukaryotic cell is called chromatin.

In eukaryotic cells, when the cell is not in the process of division, the DNA does not exist in the form of visible chromosomes. Instead, it is combined with a variety of proteins to form chromatin. Chromatin structure varies in its degree of condensation; it is less condensed in regions referred to as euchromatin, which is associated with genes that are actively transcribed, and more condensed in regions known as heterochromatin, which generally contains genes that are not being expressed.

Chromatin and Nucleosomes

DNA in eukaryotic chromatin is organized into a repetitive unit called a nucleosome. Nucleosomes consist of DNA wrapped around a core of eight histone proteins, resembling beads on a string. The tight binding of DNA around these histone proteins allows the large DNA molecules to be packaged within the relatively small nuclear space. The chromatin can be further compacted through additional folding, involving more non-histone proteins, to form the dense structure of euchromatin and heterochromatin characteristic of non-dividing cells.

The structure is markedly different from the DNA packaging in prokaryotic cells, which don't have nucleosomes. Prokaryotic DNA is typically circular and localized to a specific area in the cell known as the nucleoid, where it interacts with nucleoid-associated proteins that help organize and compact the DNA. Although these proteins serve a packaging function similar to histones, they are distinct from the histone proteins that are found in eukaryotes.