When are chromosomes formed? How do you know? Chromosomes are formed during the S phase of interphase. "S phase: The period during which DNA is synthesized." Chromosomes are formed during anaphase. "At the end of anaphase, each pole contains a complete compilation of chromosomes." Chromosomes are formed during the G2 phase of interphase. "The cell synthesizes proteins and continues to increase in size." Chromosomes are formed during Read the sentence from the section "Interphase."In most cells, there is a narrow window of time during which DNA is synthesized. Which of the following words, if it replaced the word "synthesized" in the sentence above, would CHANGE the meaning of the sentence? tested