Nedelcheva-Veleva MN , Krastev DB , Stoynov SS .

	Figure 1. Regulation of DNA synthesis by Mec1-checkpoint pathway. (A) Replication fork during unperturbed DNA replication. (B) Regulation of DNA synthesis and replicative unwinding when DNA synthesis is disturbed. (C) The presence of extensive single stranded loops in mrc1, csm3 and tof1 mutants impeding the passage through a cohesin ring and the establishment of sister chromatid cohesion.
	Figure 2. Unwinding of DNA containing ssDNA break according to the ‘wedge’ and ‘ploughshare’ model. (A) DNA unwinding, according to the ‘wedge’ model. (B) Unwinding of DNA, containing ssDNA break at strand where the helicase is moving, according to the ‘wedge’ model. (C) Unwinding of DNA, containing single-stranded break at the opposite DNA strand according to the ‘wedge’ model. (D) Mechanism for DNA unwinding based on the ‘ploughshare’ model.
	Figure 3. Unwinding of DNA containing ssDNA break according to the ‘torsional’ model. (A) Mechanism for DNA unwinding based on the ‘torsional’ model. (B) DNA unwinding when there is an ssDNA break, according to the ‘torsional’ model. (C and D) Origin DNA unwinding and loading of polymerase α/primase according to the ‘torsional’ model.
	Figure 4. Unwinding of DNA containing ssDNA break according to the ‘rotary pump’ model. (A). DNA unwinding, according to the ‘rotary pump’ model. (B) Unwinding of DNA, containing ssDNA break based on the ‘rotary pump’ model. (C) Mechanism for DNA unwinding based on the ‘SV40’ model. (D) Unwinding of DNA, containing single-stranded DNA break based on the ‘SV40’ model.

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