1) Living organisms use DNA as their genetic material. Outline how DNA is replicated within the cells of living organisms. [8] ..... (Answer)

Replication is the process where DNA is copied, creating two identical DNA strands.  This occurs in the nucleus and is done prior to nuclear and cell division (creating 2 identical cells).

Replication is semiconservative, wherein each new DNA strand made is half new, half old.

Helicase is the enzyme that untwists and unzips DNA, creating the Y-shaped replication fork, the two opened strands of DNA behind it.

RNA primase lays down a short section of RNA primer at the 3’ end of the old DNA strand.

This allows DNA polymerase III to fit to the old DNA strand where it reads the old code in the 5’ to 3’ direction. New DNA is laid down in the 5’ to 3’ direction.

DNA polymerase I is the enzyme that removes the RNA primer from the new strand and replaces it with DNA nucleotides.

DNA ligase joins adjacent Okazaki fragments on the lagging strand and any sections of new DNA on the leading strand that need to be joined.

The leading strand of DNA is the new strand laid down in the direction of the replication fork.

The lagging strand of DNA is the new strand laid down in the opposite direction of the replication fork. This strand must be laid down in short sections known as Okazaki fragments as new sections of the lagging strand are opened up at the replication fork.

DNA replicates at multiple sites to speed up replication.