Question

A man has a condition that causes his gametes undergo meiosis I normally, but there is nondisjunction of the sex chromosomes in meiosis II. His wife has normal gametes They have a child with Klinefelter syndrome (47, XXY). He thinks his partner has been unfaithful. If he right to think so?

Which statement correctly describes transcription: 1) complementary bases on both strands of a DNA molecule 2)Nucleotides bind to complementary bases on one strand of a DNA molecule

3) A pre-formed RNA molecule binds to one strand of DNA 4)  A pre-formed RNA molecule binds to both strands of DNA

d. A pre-formed RNA molecule binds to both strands of a DNA molecule

Answer 1

2) Nucleotides bind to complementary bases on one strand of a DNA molecule, is the correct answer for this question.

Transcription is the process by which a DNA molecule encodes for a RNA molecule (also called as a transcript) . During this event, only one of the strands of the DNA molecule i.e., the coding strand or the sense strand of the DNA is used as a template for transcription. Therefore, nucleotides bind to complementary bases on one strand of a DNA molecule to bring about transcription.

During this process of transcription the single coding DNA strand is bound by a RNA polymerase enzyme and complementary nucleotides (essentially Ribonucleotides) are added opposite to the DNA bases by a mechanism of nucleophilic attack leading to the formation of a complete RNA molecule.