how do polymerase construct a new complementary chain of nucleotides?

Answer 1

Polymerases are enzymes that use an existing template to synthesize a new strand of nucleic acid. The enzyme can read single strands of DNA, and synthesize a complementary strand of DNA (DNA replication), or RNA (mRNA synthesis, known as transcription).

The DNA strand that is read is referred to as the SENSE strand, and the POLYMERASE enzymes use this template, and free deoxyribonucleotides (or just ribonucleotides) to synthesize a new strand of DNA (or RNA). Note that REVERSE TRANSCRIPTASE is an enzyme found in cells (especially RNA viruses) that synthesizes DNA based on a RNA template.