Restriction Point
There is a "restriction point" present at the end of G1 phase. This point is a series of safeguards to ensure the DNA is intact and that the cell is functioning normally. Functionally, the safeguards exist as proteins known as cyclin-dependent kinases (CDK). The G1 CDK proteins activate the transcription factors for a variety of genes.These include genes which are responsible for DNA synthesis proteins and S phase CDK proteins.
Read more about this topic: G1 Phase
Famous quotes containing the words restriction and/or point:
“If we can find a principle to guide us in the handling of the child between nine and eighteen months, we can see that we need to allow enough opportunity for handling and investigation of objects to further intellectual development and just enough restriction required for family harmony and for the safety of the child.”
—Selma H. Fraiberg (20th century)
“Consider a man riding a bicycle. Whoever he is, we can say three things about him. We know he got on the bicycle and started to move. We know that at some point he will stop and get off. Most important of all, we know that if at any point between the beginning and the end of his journey he stops moving and does not get off the bicycle he will fall off it. That is a metaphor for the journey through life of any living thing, and I think of any society of living things.”
—William Golding (b. 1911)