Molecular Biology; 3

DNA REPLICATION PROKARIOTIC, EUKARIOTIC CELLS

Prokaryotes

Nucleoid:

- Single, circular chromosomal DNA (prokaryotic chromosome).

- Structural and functional genes to generate a copy of the prokariot organism.

- Transmission by binary fission (cell division)

Plasmid:

- Separate smaller circular DNA structures

- Genes that may benefit survival of the organism (e.g. antibiotic resistance)

- Transmission by horizontal gene transfer (conjugation).

DNA is circular and has a single replicon (in bacteria)

DNA replication steps;

1) DNA unwinds- repeating 9 neuclotides (9mers) is where initial binding occurs. Helicase steps in too. Unwinding leads to supercoiling which is relieved by DNA gyrase.

2) DNA priming

3) DNA synthesis-

Roles of DNA polymerases:

- DNA polymerisation (polymerase activity)

- DNA proof reading (exonuclease activity)

- DNA…