Which Of The Following Terms Describes The DNA–Protein Complexes That Look Like Beads On A String?  

The first organizational level is the packaging and winding of DNA strands into histone proteins. Histones are packaged in order of DNA in so-called nucleosome complexes, which control access to protein DNA regions (Figure 1a).

Under the electron microscope, the winding of DNA in and out of the histone protein forms nucleosomes that look like small spheres on a string (Figure 1b). 

 If we look under the electron microscope at the twisting of DNA around histone proteins, it resembles small pearls on a string. These beads move around the cord without changing the structure of the cord.

Histone proteins form pearls by moving DNA around the strand without altering the entire structure of DNA.  

 Histones, the primary protein component of chromatin, bind to DNA and act as anchors like the strand winch. The DNA is wrapped in the structure of euchromatin around histone proteins in the form of nucleosomes (also called pearls on a string).

Several histones envelop a 30-nanometer-long fiber that consists of a nucleosome array in its most compact form (heterochromatin). 

Beads or strands of chromatin DNA protein complexes are called nucleosomes. Nucleosomes wrap compact chromatin fibers into long strands, and they form most of the chromosomal DNA chromatin in living cells by taking on an elongated bead or string shape.

They are stacked on top of each other to create a regular set of DNA that condenses. Nucleosomes with 20-60 base pairs of left DNA can be formed under non-physiological conditions as 10 nm beads or fibrous strands.

In the core of a lysis electron microscope lattice most chromatin can be seen in the form of a fiber with a diameter of about 30 nm, but also chromatin beads and strands can be formed (see below ).   

Chromatin is the material of a series of nucleosomes (DNA) that take various forms depending on whether the cell undergoes cell division or genetic transcription. Nucleosome structures are formed when DNA is attached to two pairs of four histone proteins.

When several nucleosomes with about 200 base pairs of DNA occur, they make chromatin appear like pearls on a string as it unfolds.   

 This process involves chemical changes to the histone proteins, which occur as octamers in chromatin. The methylation and acetylation processes are important changes in the form of chromatin that enable gene transcription and mitosis (meiosis).  

 It is possible that cells create proteins that last for months; hemoglobin in red blood cells is a good example. However, many proteins do not last very long, as they are broken down into days, hours, or even minutes.

One possibility is to modify the chromatin structure so that genes are transcribed to produce histone proteins that are charged. 

Regulatory basal transcription factors regulate transcription by binding to promoters. The human hormone testosterone enters the cell and binds to certain proteins that switch certain sites in the DNA of the cells on or off. 

The DNA of eukaryotic cells is located on membranes and is bound to organelles known as cell nuclei. DNA is bound to proteins known as histones to form chromatin material. Chromatin structure changes enable such processes in DNA during replication and transcription processes. 

 

During mitosis and meiosis, the complex DNA proteins (RNA) found in eukaryotic cells during the anaphase facilitate the correct separation of chromosomes; the characteristic shape of the chromosomes which is visible during this process is the result of the condensation of DNA coils into chromatin.

These proteins prevent strands from tangling and play an important role in strengthening DNA during cell division, preventing DNA damage, and controlling gene expression and DNA replication.

What drives the chromatin remodeling machine is a change in the nucleosome structure that biologists assumed for many years formed certain positions in the DNA nucleosomes that remained fixed in close connection with the nucleus histones of the DNA. 

 

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