LIFESCI 7C Lecture 1: LS 7C Week 1 lect 1 part 3
Document Summary
The cell is the fundamental unit of living organisms (chapter 1). Some estimates place the number of cells in an adult human being at between 50 and 75 trillion, whereas others place the number at well above 100 trillion. Tissues are held together and function as a unit because of cell junctions. Cell junctions physically connect one cell to the next and anchor cells to the extracellular matrix. Some tissues have cell junctions that perform roles other than adhesion. Then if he swirled the cells together, they would coalesce back into a group resembling a sponge. There are many different kinds of cadherin, and a given cadherin may bind only to another cadherin of the same type. This property explains holtfreter"s observations of the cells from amphibian embryos. The extracellular domain of a cadherin molecule binds to the extracellular domain of a cadherin of the same type on an adjacent cell.
