CELL CYCLE STAGE G1
Stage G1 (from the Eng. gap) is one of the three sequential stages of the resting stage of the cell cycle. This is the presynthetic, or, postmitotic stage. During G1 intensive processes of biosynthesis, formation of mitochondria, chloroplasts (in plants), endoplasmic reticulum, lysosomes, Golgi complex, vacuoles, and vesicles occur in a cell. Nucleolus produces rRNA, mRNA and tRNA; ribosomes are for med; the cell synthesizes structural and functional proteins. Intensive cell metabolism, controlled by enzymes, and cell growth occur. Differences in duration of the cell cycle in various cell is determined mainly by stage G1. In the late stage G1 the restriction point exists, in which the cell cycle can be safely stopped. It is related to the beginning of the rest period.