Question

Genes are located in
A) Ribosomes
B) Sphaerosomes
C) Lysosomes
D) Chromosomes

Answer 1

A gene is the basic physical and functional unit of heredity. Gene is a specific segment of DNA that determines the biological character of an organism.

Complete answer:
Option A: Ribosomes are found in all cells, prokaryotes as well as eukaryotes. The ribosomes can be seen in the cytoplasm of the cell in DNA and chloroplast. They are of two types - 70S and 80S. At the time of protein synthesis, several copies of a particular polypeptide are formed, many ribosomes line up and form on the mRNA chain, such a string of ribosomes are called polysomes. Ribosomes help in protein synthesis, hence known as “protein factories” of the cell. Therefore, this is an incorrect option.

Option B: They are found in plant cells and are involved in the synthesis and storage of lipids i.e. endosperm and cotyledons of oil seeds. They contain hydrolytic enzymes like protease, ribonuclease, phosphatase, esterase, etc. They are bounded by a single unit membrane. The main function of them is to help in lipid metabolism. They are known as plant lysosomes. Therefore, this is an incorrect option.

Option C: Lysosomes are absent in prokaryotic cells but are present in eukaryotic cells and protozoans. They are absent in mammalian RBCs. They are spherical in form, but plant root cells have irregular shape lysosomes. It contains dense fluid that has a hydrolytic enzyme called acid hydrolases. They are known as “suicidal bags” and also “disposal units” of cells because they digest the incoming food materials and remove the foreign bodies, toxic molecules, and debris. Therefore, this is an incorrect option.

Option D: Chromosomes are thin thread-like chromatin fibers. They can be seen in interphase. A chromosome consists of two identical halves, the chromatids, held together at a point, the centromere. A chromosome is very long, greatly coiled to be accommodated in short chromatids. The chromosomes bear hereditary units, the genes. Chromosomes carry genetic information in the form of genes. Therefore, this is the correct option.

Thus, the correct answer is option (D) Chromosomes.

Note: It is to be noted that the centromere of the chromosome appears as a narrow region, called primary constriction. The chromosome may have additional constriction i.e. secondary constriction. The part of the chromosomes beyond the secondary constriction is termed satellite second constrictions can be used as markers.