* Structural support: Proteins like collagen and keratin provide strength and shape to tissues, organs, and even the entire organism.
* Transport: Proteins like hemoglobin carry oxygen in the blood, while others transport nutrients and waste products across cell membranes.
* Movement: Proteins like actin and myosin are responsible for muscle contraction, cell movement, and other forms of cellular motion.
* Defense: Antibodies, a type of protein, are essential for the immune system's ability to recognize and fight off pathogens.
* Hormonal signaling: Some proteins act as hormones, carrying signals between different parts of the body.
* Cellular communication: Proteins on the cell surface act as receptors, allowing cells to communicate with each other and with their environment.
* Regulation of gene expression: Proteins play a key role in controlling which genes are turned on or off, influencing cellular development and function.
These are just a few examples of the diverse roles proteins play in cells. They are essential for life, and their malfunction can lead to a variety of diseases.
