Question

The circular and double stranded DNA occurs in
A. Golgi body
B. Mitochondria
C. Nucleus
D. Cytoplasm

Answer 1

Hint: DNA or Deoxyribonucleic acid is the hereditary material that contains a unique genetic code. It is made up of two long polynucleotides that wind around one another to form a shape known as a double helix.

Complete Answer:
Let us analyze each option to find out the correct answer.
Option A: Golgi body or Golgi apparatus is found in most of the cells located near the nucleus. It is flattened, membrane-bounded, parallelly arranged sacs. It helps in processing and packaging proteins and lipid molecules. It packages them in vesicles, and either stores them for later use or sends them out of the cell. Golgi apparatus consists of secretory vesicles. They lack nucleic acids like DNA and RNA but are involved in the synthesis of secretory and membrane proteins, phospholipids, enzymes, etc. Therefore, this is an incorrect option.

Option B: Mitochondria are double membrane-covered, semi-autonomous eukaryotic cell organelles whose function is cellular respiration. Prokaryotes like bacteria are characterised by the presence of a single circular molecule of DNA. Certain cell organelles, of a eukaryotic cell, like chloroplast and mitochondria, also have their own DNA. The DNA of these cell organelles is similar to prokaryotic DNA in double-stranded and circular nature. Therefore this is the correct option.

Option C: Eukaryotic cells have a distinct nucleus. The nucleus of eukaryotic cells is composed primarily of protein and deoxyribonucleic acid, or DNA. The eukaryotic cells are found in animals, plants, and fungi. The eukaryotic DNA is a linear DNA molecule. It coiled around proteins called histones, which wind the DNA into a more compact form. Therefore, this is an incorrect option.

Option D: Cytoplasm refers to the gelatinous liquid that fills the inside of a cell. It is mainly composed of water, salts, and various organic molecules. DNA is absent. Therefore, this is an incorrect option.

Thus, the correct option is B) Mitochondria.

Note: It is to be noted that DNA is made up of nucleotides. The nucleotide has two components: a backbone, made from the sugar deoxyribose and phosphate groups, and nitrogenous bases, known as cytosine, thymine, adenine, and guanine.