Question:

Beads on string like structures of A are seen in B, which further condense to form chromosomes in C stage of cell division. $\quad$$\quad$ $\quad$A$\quad$ $\quad$$\quad$$\quad$ B$\quad$$\quad$$\quad$ C

Updated On: Jul 28, 2022
  • Chromonema Chromatin $\quad$Metaphase
  • Chromatin $\quad$ Chromatid $\quad$Metaphase
  • Chromonema Chromosome Anaphase
  • Chromonema Chromatid$\quad$ Anaphase
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The Correct Option is A

Solution and Explanation

The "beads-on-a-string" structure is seen in electron microscope of isolated metaphase chromosomes. The chromonema form the gene bearing portions of the chromosome. Basically chromonema is made up of nucleosome chains. Nucleosome chain gives a beads on string appearance under electron microscope. Nucleosome is the fundamental packaging unit in eukaryotic chromosomes.
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Concepts Used:

The Molecular Basis of Inheritance

DNA Replication:

DNA synthesis is commenced at particular points within the DNA strand referred to as ‘origins’, which are certain coding regions. There are numerous origin sites, and when replication of DNA starts, these sites are mentioned as replication forks. Within the replication, the complex is the enzyme DNA Helicase, so that they can be utilized as a template for replication. DNA Primase is another enzyme that's essential in DNA replication.

RNA:

Ribonucleic acid (RNA) is an essential biological macromolecule that exists all together in biological cells. It is principally involved in the synthesis of proteins, that carry the messenger instructions from DNA, which itself contains the genetic instructions needed for the event and maintenance of life. In some viruses, RNA, in spite of DNA, carries genetic information.

Genetic Code:

Genetic code is the term we use in the manner that the four bases of DNA--the A, C, G, and Ts--are strung together in a way that the ribosome, the cellular machinery, can read them and switch them into a protein. In the ordering, every three nucleotides during a row count as a triplet and code for one amino alkanoic acid.

Read More: Molecular Basis of Inheritance