Question

An Okazaki fragment includes

• A. Only short fragments of deoxyribonucleotides
• B. Only short RNA fragments
• C. RNA primer + short fragments of deoxyribonucleotides
• D. Only RNA primer

Answer 1

The correct option is C

RNA primer + short fragments of deoxyribonucleotides

The lagging strand is synthesised discontinuously by the formation of Okazaki fragments. RNA primers are laid by the primase enzyme, and DNA polymerase adds nucleotides to the free 3’ end of each primer. Each Okazaki fragment is about 100-200 nucleotides in length, and includes the RNA primer and the deoxyribonucleotide bases added to it by DNA polymerase. Eventually, the RNA primer is replaced with deoxyribonucleotide bases by another type of DNA polymerase enzyme.