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dna replication - Coggle Diagram

- - - - single stranding binding proteins prevent strands from re annealing with each other
        
        dna primase produces rna primers to provide free 3 OH groups for dna polymerase
- - - - dna synthesis occurs in the same direction as the opening of the dna strands
  - - - new regions of dna become exposed, so new primers are produced to synthesise dna complementary to these regions-okazaki fragments
        
        okazaki fragments are linked by dna ligase
- - - - 3' overhang of the single strand-susceptible to corrosion
        
        dna ends shorten after each cell division, soon enough critical genes for survival will be lost
        
        telomeres-non coding repeated short nucleotide sequences, can be sacrificed to maintain integrity of critical genes-dna repeat sequences at 3' end of chromosome
        
        telomeres depleted can cause corrosion of critical genes. but can be extended by telomerases when cells actively divide
        
        telomerases have a piece of rna and a dna repeat sequence
        
        telomerase binds to a dna repeat sequence, synthesises a 6-nucleotide repeat sequence, moves 6 nucleotides to the right and begins synthesising another 6 nucleotides
        
        1 more item...
        
        found in germ lines and actively dividing somatic cells, reduces with age and psychological stress
        
        found in 90% of tumour cells, prevents telomere from shortening and plays a role in continued growth of cancer cells
- - - - dna polymerase i removes rna primers and fills in with new dna