Frequent question: What is meant by beads on a string model of chromatin?

What is meant by the “beads on a string” model of chromatin? The beads are the nucleosomes, and the string is the linker DNA. … A cell can form 10-nm chromatin fibers, but not 30-nm fibers.

What is beads on a string model?

Nucleosomes can be defined as structures with a basic unit of DNA packaging which consists of a segment of DNA wrapped in sequence around eight histone protein core. This is also known as beads on a string structure. So, the correct answer is ‘Nucleosomes’.

Why nucleosome is called beads on a string structure?

A nucleosome is a section of DNA that is wrapped around a core of proteins. Inside the nucleus, DNA forms a complex with proteins called chromatin, which allows the DNA to be condensed into a smaller volume. When the chromatin is extended and viewed under a microscope, the structure resembles beads on a string.

Has beads on a string structure?

Chromatin is a complex of DNA, protein and RNA found in eukaryotic cells. … DNA wraps around histone proteins, forming nucleosomes and the so-called beads on a string structure (euchromatin).

How is a protein like a string of beads?

Proteins are strings of around 300 “beads” called amino acids (though they can be much longer or shorter). There are 20 different amino acids which leads to a pretty much infinite number of proteins that can be made. Proteins form the basic machinery of the cell.

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Which state of DNA is considered a string of beads?

Consequently, during interphase, DNA is combined with proteins and organized into a precise, compact structure, a dense string-like fiber called chromatin, which condenses even further into chromosomes during cell division.

Where is nucleus located in a cell?

The nucleus is one of the most obvious parts of the cell when you look at a picture of the cell. It’s in the middle of the cell, and the nucleus contains all of the cell’s chromosomes, which encode the genetic material.

What does kinetochore mean?

Definition. The kinetochore is a protein complex assembled on the centromeric region of DNA. It provides the major attachement point for the spindle microtubules during mitotic or meiotic division to pull the chromosomes apart.

What is the difference between chromatin and chromatid?

As mentioned above, chromatin is composed of DNA and histones that are packaged into thin, stringy fibers. The chromatin undergoes further condensation to form the chromosome. … A chromatid is either of the two strands of a replicated chromosome. Chromatids connected by a centromere are called sister chromatids.

What is the structure of nucleosomes?

A nucleosome is the basic structural unit of DNA packaging in eukaryotes. The structure of a nucleosome consists of a segment of DNA wound around eight histone proteins and resembles thread wrapped around a spool. The nucleosome is the fundamental subunit of chromatin.

Who proposed bead on string concept?

75 years of science and technology

ORNL’s Don and Ada Olins were the first to discover the critical structure—the nucleosome—that winds DNA around proteins like thread around a spool.

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Is nucleosome bigger than DNA?


A nucleosome is the basic repeating unit of eukaryotic chromatin. In a human cell, about six feet of DNA must be packaged into a nucleus with a diameter less than a human hair. A single nucleosome consists of about 150 base pairs of DNA sequence wrapped around a core of histone proteins.

Which of the following has beads on a string structure?

Which of the following has beads on a string structure? Explanation: DNA winds around histone proteins forming nucleosomes: the beads on a string structure.

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