MICROANATOMY

Detailed explanation-1: -Cell differentiation is caused by changes in gene expression. This occurs when different signaling molecules in the environment activate or repress different transcription factors that are necessary to express certain genes in the DNA.

Detailed explanation-2: -Gene regulation is an important part of normal development. Genes are turned on and off in different patterns during development to make a brain cell look and act different from a liver cell or a muscle cell, for example. Gene regulation also allows cells to react quickly to changes in their environments.

Detailed explanation-3: -The gene regulatory proteins allow the individual genes of an organism to be turned on or off specifically. Different selections of gene regulatory proteins are present in different cell types and thereby direct the patterns of gene expression that give each cell type its unique characteristics.

Detailed explanation-4: -Cells differentiate because specific enzymes turn genes on and off in various cell types. Most living things are composed of different kinds of cells specialized to perform different functions.