The next phase after break-1 is called Synthesis phase or S phase or Synthesis phase. It is also called DNA replication. The characteristics of synthesis state are-
(i) Histone proteins and DNA are synthesized in subphase A.
(ii) The amount of DNA increases and doubles.
(iii) Physical elongation of chromosomes occurs and each chromosome divides to form two chromatids.
(iv) Subunits of kinetochore are formed at this stage.
(v) Division of centrosome occurs in animal cells.
(vi) At this stage inactive proteins are synthesized.
(vii) This sub-phase takes 30-50% time. Mammals take 7 hours in this state.