The Building Blocks of Life: Cells, Biomolecules, and Essential Functions
The Vital Functions
Nutrition Function
This is the process in which living beings obtain the matter and energy necessary for life.
Interaction Function
This is the process in which living things relate to their surrounding environment.
Reproduction Function
This is the process by which new individual living beings are reproduced.
- Sexual Reproduction: Requires a male and a female parent.
- Asexual Reproduction: Requires only one parent.
Biomolecules
Biomolecules are the building blocks of life, primarily composed of carbon, hydrogen, oxygen, nitrogen, sulfur, and phosphorus. Organic biomolecules are exclusive to living beings. There are four main types:
Carbohydrates
These are the most abundant biomolecules, also called saccharides. They are made up of monosaccharides and are responsible for storing and transporting energy. They also serve as structural components. Examples include glucose, fructose, and cellulose.
Lipids
These are organic compounds that occur naturally and are insoluble in water. Fats and oils are used for storing energy. Phospholipids are fundamental in the structure of cell membranes. Steroids act as sexual hormones, and waxes provide protection.
Proteins
These are macromolecules with complex structures, made up of chains of smaller amino acids. Their most important functions are to give structure to cells, transport substances around the body, regulate chemical reactions, and protect the body from bacteria and microorganisms.
Nucleic Acids
These are macromolecules formed by the union of smaller molecules known as nucleotides. Nucleic acids are found in the genetic material of cells.
- Deoxyribonucleic Acid (DNA): Stores all the information necessary for the functioning and development of living things. It is found in the cell nucleus and makes up the genetic code.
- Ribonucleic Acid (RNA): Participates in the synthesis of proteins and is found in the cytoplasm.
Inorganic Biomolecules
Inorganic biomolecules are compounds that aren’t exclusive to living beings.
Water
The most abundant inorganic biomolecule, water is present in tissues, organs, blood, and even teeth. It is used to carry out all chemical reactions, transport substances, and regulate body temperature.
Mineral Salts
These form the solid structure of living beings, such as skeletons. They are involved in chemical reactions and are necessary for the transmission of nervous impulses.
Cells
Cells are the structural and functional units of living beings. They have three basic structures:
Cell Membrane
This thin layer separates the inside of the cell from its surrounding environment.
Cytoplasm
This gel-like, semi-transparent fluid contains structures called organelles, which are responsible for cell functions.
Nucleus
This carries the genetic information of living things, which is passed from one generation to the next.
Animal Cell
Contains a cell membrane, nucleus, rough endoplasmic reticulum, vacuoles, vesicles, cytoplasm, mitochondria, and Golgi body.
Plant Cell
Contains all the components of an animal cell, plus a cell wall and chloroplasts.
Eukaryotic Cells
The genetic material is enclosed in a structure called the nucleus. Animals and plants are multicellular, eukaryotic organisms.
Prokaryotic Cells
The genetic material is enclosed in the cytoplasm. Bacteria are unicellular, prokaryotic organisms.
Cellular Nutrition
Cellular nutrition consists of all the processes in which cells obtain matter and energy to perform vital functions. Nutrients are obtained from food. Once inside the cell, the nutrients are subjected to chemical processes called cellular metabolism.
Catabolism
This is the degradation of complex organic substances into simple substances, which produces energy.
Anabolism
This is the production of more complex organic substances from simple substances, which requires energy from catabolism.
Autotrophic and Heterotrophic Nutrition
Autotrophic Nutrition
Characteristic of cells that use an energy source to make their own organic matter from inorganic matter. There are two processes depending on the energy source:
- Photosynthesis: Energy comes from the sun.
- Chemosynthesis: Energy comes from chemical reactions.
Heterotrophic Nutrition
Characteristic of cells that feed on organic matter produced by other living beings. They transform this organic matter to obtain nutrients and energy.
Cellular Respiration
Respiration is the release of energy from organic substances into living cells. All cells need energy to carry out vital functions.
Cellular respiration describes the metabolic reactions and processes that take place in a cell to obtain chemical energy from specific organic molecules. First, the cell takes in organic substances and oxygen. Then, it breaks down those substances into simpler substances, such as carbon dioxide and water. At the same time, energy is released.
Fermentation
This is the process by which cells release energy in the absence of oxygen.
Cellular Division
Cellular division is a process by which a cell, called the parent cell, divides into two or more cells, called daughter cells.
Unicellular Organisms
In unicellular organisms, cellular division replicates an entire organism, and new individuals are formed. As a result, there is an increase in the population.
- Binary Fission: First, the nucleus of the parent cell divides into two identical nuclei. Then, the parent cell divides into two identical daughter cells of the same size.
- Multiple Fission: The nucleus of the parent cell divides into several nuclei. After the nuclear divisions are complete, the cytoplasm separates. Then, each nucleus becomes encased in its own membrane to form an individual cell.
Multicellular Organisms
In multicellular organisms, cellular division results in an increase in the number of cells of an organism. This increase is reflected in the growth or repair of damaged parts of the organism.
The Five Kingdoms
Kingdom Monera
Monerans have only one cell and no nucleus. They can make their own food. Example: Bacteria.
Kingdom Protista
Some protists have one cell. Their cells always have nuclei. If a living thing has a cell with a nucleus but isn’t a plant, animal, or fungus, it is a protist. Example: Amoeba.
Kingdom Fungi
Fungi have more than one cell, and their cells have nuclei. Their cells also have a cell wall made from chitin. Fungi can’t make their own food. Examples: Mushrooms and mold.
Kingdom Plantae
Plants have more than one cell, and their cells have nuclei. Their cells also have a cell wall made from cellulose. Examples: Flowers and trees.
Kingdom Animalia
Animals have more than one cell, and their cells have nuclei. Animals can’t make their own food. Examples: Sponges, insects, fish, birds, and humans.