Here's why:
* DNA as the blueprint: Every cell in an organism contains the same DNA, acting as a blueprint for all its proteins.
* Differential gene expression: Different cells express different subsets of genes. This means they "turn on" or "turn off" specific genes, leading to the production of unique proteins.
* Protein function: Proteins are the workhorses of the cell, carrying out diverse functions. These functions determine the cell's structure, shape, and behavior.
For example:
* Muscle cells express genes for proteins like actin and myosin, which enable them to contract and generate force.
* Nerve cells express genes for proteins involved in transmitting electrical signals.
* Red blood cells express genes for hemoglobin, the protein responsible for oxygen transport.
This differential gene expression allows cells to specialize, leading to the wide variety of cell types found in complex organisms.
Therefore, despite having the same DNA, cells look and behave differently due to the specific genes they express and the proteins they produce.
