Why is DNA packaged into chromosomes

Because DNA alone cannot be replicated, it must be combined with proteins to complete replication, chromosomes are a combination of DNA and proteins; DNA is deoxyribonucleic acid.

Chromosomes can replicate in cells, mainly to ensure stability in cell generations, and must have the ability to replicate autonomously, ensure the integrity of replication, and distribute genetic material equally.

Packaged into chromatin contains two elements:

1.binds to histones;

supercoiled and other structures.

Histones, in general, it plays the role of modification:

There are five types: H1, H2A, H2B, H3, H4, which are rich in positively charged basic amino acids.

1. Acetylation of H3·H4 can open an open chromatin structure and increase gene expression.

2. The synergistic effect of DNA methylation and histone deacetylation is jointly involved in transcriptional repression.

3. In addition, M i22 NURD also has chromatin remodeling activity, so S in 3 and M I22 NURD may play a role in long-term and short-term transcriptional repression regulation, respectively.

In the mammalian genome, histones can be modified in many forms. A nucleosome consists of an octamer consisting of two H2A, two H2B, two H3, two H4 and 147 bp of DNA wrapped around the outside. The core parts of the histones that make up nucleosomes are roughly homogeneous, and the free N-terminus can be modified in a variety of ways, including acetylation, methylation, phosphorylation, ubiquitination, ADP ribosylation, etc. , all of which affect the transcriptional activity of genes.

Biological significance of supercoiling:

1. DNA is compressed and packaged to make it much smaller in size.

2. Increase the stability of DNA.

3. May be related to the regulation of replication and transcription.

Overall, the packaging of DNA into chromatin is very important for cells, because the stability of DNA preservation and the accuracy of replication are the priority of cells.

DNA is not all in chromosomes, but also in cells.

Germ cells are not counted as somatic cells.

A: Is DNA all on chromosomes?

The answer is, not necessarily.

1: In the case of eukaryotes, DNA is present in the nucleus, mitochondria, chloroplasts (plants).

2: For prokaryotic microorganisms, some eukaryotic microorganisms (e.g., some fungi) may also have circular plasmids, that is, circular DNA molecules.

3: For viruses that use DNA as their genetic material, it doesn't matter about chromosomes. (does not have a cellular structure).

B: Germ cells are not part of the somatic cells.

No. Reason (omitted).

It's not the same thing.

Chromosomal replication includes the synthesis of proteins in addition to DNA replication.

The specific DNA replication is as follows: The separation of the double-stranded nucleic acids is a step-by-step process in which several replication machine-functioning biocatalytic enzymes read the information of the parent DNA and establish a new nucleotide body according to the party principle of A-T and G-C, which also involves the transmission of DNA information through the mediation of RNA.

Two separate parent nucleotide single strands are linked together with two new nucleotide bodies to form two new double-stranded nucleic acids, thus enabling DNA replication.

DNA replication is accomplished by the synergistic replication of multiple proteins, including DNA polymerases, DNA helaxases, initiating enzymes, and several accessory proteins. As early as 60 years ago, it was confirmed that DNA is genetic material and the double helix structure of DNA was resolved.