Question

Cells taken from different tissues in the human body, such as muscle cells and liver cells, are structurally and functionally different from each other because

• A. They have different numbers of chromosomes.
• B. They are expressing different genes.
• C. The contain different ribosomal subunits.
• D. They contain different genes.

Answer 1

The correct option is B They are expressing different genes.

Multicellular organisms need specialisation in order to survive. Every cell nucleus contains the complete genome established in the fertilised egg. DNAs of all differentiated cells are identical. The unused genes in differentiated cells are not destroyed or mutated, and they retain the potential for being expressed. Only a small percentage of the genome is expressed in each cell, and a portion of the RNA synthesized in the cell is specific for that cell type. Thus, the correct answer is option B.