Question

Which one is incorrect?

• A. DNA replication occurs before mitosis and meiosis
• B. The polarity of the DNA template on which the continuous strand forms is 5' → 3'
• C. The transcribed products of genes can be rRNA, tRNA and mRNA
• D. both (a) and (c)

Answer 1

The correct option is B The polarity of the DNA template on which the continuous strand forms is 5' → 3'

When a cell has to divide into two daughter cells by mitosis or four daughter cells by meiosis, it needs to double the content of genetic material. Doubling of DNA content (DNA synthesis) takes place during the S phase (synthesis) of the cell cycle. The cell enters into division phase (meiosis or mitosis) only after completion of interphase ($G_1$, S and $G_2$) of the cell cycle. Therefore, DNA replication occurs before mitosis and meiosis.

Template DNA getting transcribed to RNA, can form rRNA, tRNA and mRNA as per the requirements of the cell.

The polarity of the DNA template on which the continuous strand forms is 3'→5' because the synthesis of the new DNA strand (continuous strand) takes place in the 5' → 3' direction.

Therefore, the incorrect statement is: the polarity of the DNA template on which the continuous strand forms is 5'→ 3'.