* Genetic Information: DNA holds the instructions for building and maintaining an organism. It's like a codebook containing the recipes for all the proteins and other molecules a cell needs to function.
* Heredity: DNA is passed down from parent cells to daughter cells during cell division. This ensures that offspring inherit the genetic information necessary to develop and function.
* Cellular Processes: DNA directs all the activities within a cell, including:
* Protein synthesis: DNA provides the instructions for creating proteins, which are essential for everything from structural support to enzymatic reactions.
* Cell growth and division: DNA controls the timing and regulation of these processes.
* Repair and maintenance: DNA helps cells repair damaged components and maintain their integrity.
Why different cells have *different* DNA:
While all cells in an organism have the same genome (complete set of DNA), they don't necessarily have the same genes expressed. This is what leads to the specialization of cells.
* Gene Expression: Different cells in an organism activate (express) different genes. For example, a muscle cell expresses genes for muscle proteins, while a brain cell expresses genes for neurotransmitters.
* Cellular Differentiation: The process of gene expression is what leads to the development of specialized cells with unique functions.
In summary: All cells need DNA for their basic functioning and to inherit genetic information. Differences in gene expression within a multicellular organism lead to the specialization of cells and the creation of diverse tissues and organs.
