Structural Support and Movement:
* Collagen and elastin: Provide strength and flexibility to connective tissues, such as skin, tendons, ligaments, and bones.
* Keratin: Forms hair, nails, and feathers, giving them their structure and protection.
* Actin and myosin: Responsible for muscle contraction, allowing movement and locomotion.
Enzymes:
* Catalyze chemical reactions: Enzymes are biological catalysts that speed up reactions without being consumed themselves. They are highly specific, often acting on only one type of molecule.
* Essential for metabolism: Enzymes drive all metabolic processes, from breaking down food to building complex molecules.
Transport and Storage:
* Hemoglobin: Carries oxygen in the blood.
* Albumin: Transports fatty acids and steroids in the blood.
* Ferritin: Stores iron in cells.
Hormones and Signaling:
* Insulin: Regulates blood sugar levels.
* Growth hormone: Stimulates growth and development.
* Antibodies: Part of the immune system, recognizing and binding to foreign invaders.
Defense:
* Antibodies: Bind to and neutralize pathogens, such as bacteria and viruses.
* Complement proteins: Help activate the immune response.
* Coagulation factors: Contribute to blood clotting and wound healing.
Other Roles:
* Cell receptors: Proteins on cell surfaces that receive signals from other cells.
* Transcription factors: Regulate gene expression, determining which genes are turned on or off.
* Motor proteins: Move organelles and molecules within cells.
Overall, proteins are essential for life and carry out a diverse range of functions that are crucial for maintaining the structure, function, and survival of organisms.
