Fundamental Biology: Vital Functions and Biomolecules
Vital Functions of Living Things
Living things eat, breathe, and release waste products. We perceive and respond to changes in the environment, grow, and reproduce. These are known as vital functions.
Nutrition and Respiration
- Food and nutrition: We incorporate substances from the environment through feeding. Upon reaching the cells, substances are transformed by chemical reactions into energy and matter; this process is called nutrition.
- Breathing: We obtain the energy contained in ingested food through respiration.
- Release of waste products: As a result of respiration and food processing, toxic substances occur if they accumulate. Excretion is the process by which these waste substances are expelled to the exterior. The main products are carbon dioxide, water, and ammonia.
Interaction and Growth
- Response to environmental changes: We relate to our environment; that is, we detect changes (stimuli) in the surroundings and develop appropriate responses.
- Growth: An increase in size throughout our life. Growth manifests as an increase in cell size, cell number, or both.
- Reproduction: We produce offspring that are identical or similar to us.
The Composition of Living Things
All living things are composed of cells and consist of the same type of chemicals called biomolecules. These are composed of a series of chemical elements called bioelements.
Inorganic Biomolecules
These are present in both living and non-living things.
- Water: The most abundant substance in all living things. As a main component of cells, it carries out all chemical reactions in the body and is the medium for transporting substances.
- Mineral salts: They play different roles and participate in functions such as nerve impulse transmission and muscle contraction.
Organic Biomolecules
These are unique to living beings.
- Carbohydrates: Molecules composed of monosaccharides, such as glucose. The union of several monosaccharides forms polysaccharides, such as starch or cellulose.
- Lipids: These include fats (energy reserves) and cholesterol.
- Proteins: Macromolecules formed by the union of several molecules called amino acids. They perform many functions: structural (collagen), transport (hemoglobin), defense (antibodies), and regulating chemical reactions (enzymes).
- Nucleic Acids: There are two types: deoxyribonucleic acid (DNA), responsible for storing and transmitting information for the development and functioning of living organisms, and ribonucleic acid (RNA), which assists in protein synthesis.
Principles of Cell Theory
- The cell is the structural unit of living things.
- The cell is the functional unit of living things.
- Every cell arises, by division, from another pre-existing cell.