Biology 1202B Lecture Notes - Lecture 15: Chromatin Remodeling, Lac Operon, Histone H1
Document Summary
Human egg when released from the ovary is almost completely metabolically inactive. Within seconds of the egg and sperm meeting, rapid cell division (mitosis) Mitosis (growth) produce cells of the body. Cells differentiate into specialized cells with different functions from the same template. Every nucleated cell of the body contains the same dna template and genes i. e. liver cells do not contain different dna than skin cells. Structural and functional differences in cell types result from the presence or absence of the products resulting from expressed (transcribed or transcribed and translated) genes rather than the actual presence of genes themselves on dna. In order for cells to become specialized it is not just enough to have a gene present in dna. Gene must be expressed or not expressed in the correct tissue (special) and at the correct time (temporal). Gene expression is like music played by an orchestra.