Cellular Organization: Abiotic and Biotic Levels Explained
1. Levels of Organization: The Atom in the Body
All matter in the universe is made up of atoms. Living beings are also composed of atoms, although we are a complex mix of chemicals, highly organized into complex structures. The successive structural complexity that organizes matter, from the atom to the creature, is known as organizational levels.
1.1 Levels of Organization
1.1.1 Abiotic Levels
Abiotic levels comprise different levels of organization of matter without life.
- Atomic Level: This is the lowest level and consists of atoms of chemical elements like carbon and hydrogen.
- Molecular Level: Here, atoms are joined to each other via links and create molecules.
- Macromolecular Level: Molecules form macromolecules such as proteins.
- Cellular Organelles: Macromolecules join together to form cellular organelles.
1.1.2 Biotic Levels
Biotic levels are different levels made up of living matter.
- Cellular Level: Cellular organelles come together to form the basic unit of life: the cell.
- Tissues: Cells that perform the same function are grouped to form different tissues.
- Organs: Tissues together form different organs, which are specialized structures that function together.
- Systems: Organs are grouped into systems.
- The Body: All systems together form a multicellular individual, such as a plant, an animal, or a human being.
Abiotic to Biotic Transition
It is difficult to know which was the first living organism on Earth, but it is thought that it might have been organic molecules (lipids, amino acids) that lived in ancient oceans millions of years ago. These organic molecules are thought to have formed with the help of solar radiation, radiation from rocks, and radioactive discharges from the sky, acting on the molecules in the oceans.
2. Cellular Organization
Living beings, without exception, are formed by cells, either one (unicellular organisms) or several (multicellular organisms). Depending on the structure of the cell, these cells may be prokaryotic or eukaryotic. Prokaryotes are cells that evolved earlier than eukaryotes; they are more primitive, like current bacteria. The eukaryotic cell is more evolved with a more complex structure.
2.1 The Cell
The cell is the simplest structure capable of performing all vital functions: nutrition, reproduction, etc. Therefore, it is the basic unit of living beings. The shape of the cells depends on their function within a multicellular individual and the lifestyle in unicellular organisms. Cells may have different shapes: filiform, cubic, plane, etc.
2.1.1 Common Structures
All cells have common structures with similar features:
- Plasma Membrane: Limits and separates the cell. Through the cell membrane, it exchanges materials, energy, and information with the external environment.
- Cytoplasm: It is a liquid where the organelles are located and where chemical reactions occur.
2.2.1 The Prokaryotic Cell
It is the most primitive and simple cell. It has no nucleus, and genetic material is free in the cytoplasm. Practically the only organelles in the cytoplasm are ribosomes, which are responsible for manufacturing proteins. Some prokaryotic cells have flagella, which are appendages that allow them to move.
2.2.2 The Eukaryotic Cell
It is more evolved and complex. It differs from the prokaryotic cell in that the genetic material is separated from the cytoplasm by a nuclear membrane, forming the cell nucleus. There are two types of eukaryotic cells: animal and plant cells.
- Nucleus: The control center of the cell, containing all the genetic information.
- Ribosomes: Responsible for the manufacture of proteins.
- Mitochondria: Organelles that obtain energy from organic products.
- Golgi Apparatus: Responsible for expelling substances outside the cell.
- Endoplasmic Reticulum: A set of interconnected sacs that transport proteins and lipids throughout the cell.
- Vacuole: Its function is to store various substances.
- Lysosomes: Responsible for transforming complex substances into simpler ones.
- Cytoskeleton: A set of filaments that form the skeleton of the cell.
- Membrane: The outer layer of the cell.