Question

Linker DNA is present in between which of the following options?
A) Two nucleosome
B) Two chromatid
C) Two solenoid
D) Chromomere

Answer 1

DNA is the chemical name for the molecule in all living things that carries genetic instructions. The DNA molecule is made up of two strands that loop around each other to form a double helix shape. The backbone of each strand is made up of sugar (deoxyribose) and phosphate groups that alternate.

Complete answer:
Linker DNA connects to histone H1 and histone H1 sits on the nucleosome core. Nucleosome is technically the consolidation of a nucleosome core and one adjacent linker DNA; however, the term nucleosome is used freely for solely the core. Linker DNA may be degraded by endonucleases.

Option A) Two nucleosomes – is the correct answer because Between two nucleosome cores, linker DNA is double-stranded DNA that, in conjunction with histone H1, binds the cores together. Histone H1 sits on the nucleosome core, and linker DNA binds to it. Technically, a nucleosome is the combination of a nucleosome core and one adjacent linker DNA; however, the term nucleosome is often used to refer to only the core. Endonucleases can break down linker DNA.
Option B) Two chromatids – is an incorrect answer because a chromatid is one half of a chromosome that has been duplicated. One chromosome is made up of one DNA molecule before replication. The DNA molecule is copied during replication, and the two molecules are referred to as chromatids.
Option C) Two solenoid - is an incorrect answer because the solenoid structure of chromatin serves as a model for the thirty-nanometer fibre's structure. It's a secondary chromatin structure that lets eukaryotic DNA get packed into the nucleus.
Option D) Chromomere - is an incorrect answer because during prophase of meiosis and mitosis, chromomeres are tiny bead like structures visible on chromosomes.

Hence, the correct answer is Two nucleosomes i.e, option ‘A’.

Note: The linkers are oligonucleotides, which are short double-stranded DNA segments. These contain restriction enzyme target sites for one or more restriction enzymes. EcoRI and sal-I linkers are the most commonly used linkers.