Are nucleosomes and chromosomes the same?

Figure 1: Chromosomes are composed of DNA tightly-wound around histones. Chromosomal DNA is packaged inside microscopic nuclei with the help of histones. These are positively-charged proteins that strongly adhere to negatively-charged DNA and form complexes called nucleosomes.

Do chromosomes contain nucleosomes?

Chromosomes are made up of a DNA-protein complex called chromatin that is organized into subunits called nucleosomes. The way in which eukaryotes compact and arrange their chromatin not only allows a large amount of DNA to fit in a small space, but it also helps regulate gene expression.

What makes up a nucleosome?

Each nucleosome consists of a protein octamer, made up of two copies each of histones H2A, H2B, H3 and H4, which, together with the fifth histone, H1, organizes about 200 base pairs (bp) of DNA. Further organization involves the assembly of nucleosomes into higher-order chromatin structures.

What is the basic unit of chromosome?

The subunit designation of the chromosome is chromatin. The fundamental unit of chromatin is the nucleosome. The nucleosome consists of about 200 bp wrapped around a histone octamer that contains two copies of histone proteins H2A, H2B, H3 and H4. These are known as the core histones.

What is the main function of nucleosome?

Whereas the core nucleosome is thought to serve as a packaging device for the coiling and contraction in length of genomic DNA, we suggest that it serves primarily in the regulation of transcription. A nucleosome on a promoter prevents the initiation of transcription.

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