in this lesson we'll be looking at the cell cycle this is the lifespan of a eukaryotic somatic cell a somatic cell is any cell in the body of an organism except for sex cells such as sperm and egg cells the cell cycle describes the sequence of cell growth and division a cell spends most of its life in a state called interphase interphase has three phases the g1 s and g2 phases interphase is followed by cell division which has one phase the m phase together these four phases make up the entire cell cycle g1 of interphase is sometimes called growth one or gap phase one in g1 a cell is busy growing and carrying out whatever function it's supposed to do note that some cells such as muscle and nerve cells exit the cell cycle after g1 because they do not divide again a cell enters the s phase after it grows to the point where it's no longer able to function well and needs to divide the s stands for synthesis which means to make because a copy of dna is being made during this phase once dna replication is complete the cell enters the shortest and last part of interphase called g2 also known as growth 2 or gap phase 2. right now it's enough to know that further preparations for cell division take place in the g2 phase now that interphase is over the cell is ready for cell division which happens in the m phase the m phase has two events the main one is mitosis which is division of the cell's nucleus followed by cytokinesis a division of the cytoplasm so at the end of m phase you have two daughter cells identical to each other and identical to the original cell let's review the cell cycle describes the life cycle of an individual cell it has four phases three in interphase and one for cell division most cell growth and function happen during g1 the cell enters the s phase when it needs to divide in this phase the cell replicates its dna replication just means the cell makes a copy of its dna in g2 the cell undergoes further preparations for cell division finally we have cell division in the m phase the m phase consists of mitosis which is nuclear division and cytokinesis or division of the cytoplasm we'll explore the details of mitosis and cytokinesis separately [Music] you