I have tried to make this overview as precise, brief and simple as possible, but at the same time interesting to everybody, no matter your scientific and general knowledge background. It definitely wasn't an easy balance. Since we're passing over practically every science out there, making no mistakes was completely unrealistic, so I had to fight the austere perfectionist inside me to give this a shot. You might find some things difficult or some things not quite correct. If you belong to the former, don't get disappointed, the point is not to understand everything, but rather to get an idea about the structure of the Cosmos and get stimulated to learn more about it. Lots of links will redirect you to Wikipedia articles where you can read more about the various concepts discussed and at the end of the article you can find pictures for every level. If you belong to the latter, forgive my mistakes and send me some feedback about how I can make this even better, keeping in mind that the purpose of this article is not to be published in a scientific magazine. Enjoy!
Matter has self-assembling properties. Here we’ll discuss the levels of its organization from the subatomic particles to the universe, even though more will probably be discovered as science progresses. Life, expressed by the levels between the macromolecules and the biosphere, is a branch of the organization of matter, since it is not necessary for the formation of the following levels. Also, this is only how life the way we know it on Earth is organized. We don't know that this is the only way "life" can be formed, as we haven't encountered any other type of life either on or off our planet. In any case, for the greater part of the universe, where there is no life, we pass from molecules directly to cosmic dust.
Elementary subatomic particles are unknown to have substructure, thus unknown to be composed of other particles. All elementary particles are, depending on their spin, either fermions or bosons. Fermions are the matter (quarks and leptons) and antimatter (antiquarks and antileptons) particles. The electron is a lepton. Bosons are “force particles”, i.e. they mediate interactions among fermions. So, fermions could be considered the structural unit of matter, while bosons are the mediators of the fundamental forces of nature (gravitational, electromagnetic, strong nuclear, and weak nuclear) that affect matter.
Combinations of elementary particles form the composite particles. Protons and neutrons are composite particles, each of them formed by three quarks, and together they form the nuclei of atoms.
The atom is consisted of the nucleus and the electrons that are distributed around it. Depending upon the number of neutrons and protons of the nucleus, the atom belongs to a different chemical element. Every element has its own chemical properties, which dictate the way it interacts with the other elements.
The interactions of atoms lead to the formation of chemical bonds among them and the creation of a molecule. Every molecule has its own chemical properties, that result from the atoms that form it and the type of bond that connects them. This combination leads to “emergent” properties that the atoms themselves, when unbound, do not necessarily exhibit.
Molecules made of two or more different elements are called chemical compounds. Compounds that consist of any elements but carbon are called inorganic, while those that contain carbon are called organic.
3.1 MacromoleculesOn certain occasions, many similar or identical compounds, the monomers, form long chains, the polymers. Organic polymers are very big molecules that exhibit, in turn, new (bio)chemical properties, like storing of information and complex and highly selective catalytic function (enzymes). Being very big, they are vulnerable and quickly split to their components when they are free in the environment. However, when they are protected, say, by a double layer of lipids, such as a cell membrane, they can persist, interact and form life, they way we know it on our planet. The macromolecules on which life depends are carbohydrates, proteins, nucleic acids and lipids (lipids are not true macromolecules, but are basic to life and are often mentioned along with the others).
3.2 OrganelleThe organelle is an organized collection of macromolecules and inorganic molecules within the cell that performs certain specific functions. For example, the mitochondrion is an organelle that contains macromolecules of all types, with the basic function of producing energy.
3.3 CellThe cell is a collection of organelles and inorganic molecules (water, sodium, potassium etc) and it is the structural unit of life. It's the smallest possible entity that presents the characteristics of life and, therefore, that can be considered “alive”. Some cells constitute an organism themselves (unicellular organisms), while others live in groups (multicellular organisms).
3.4 TissueIn multicellular organisms, cells can differ from each other. A group of similar cells that execute the same functions constitutes a tissue. For example, muscle tissue comprises many similar cells, the muscle cells (or muscle fibres), which have the same characteristics, including the ability to contract. The other three basic tissue types are the nerve, the epithelial and the connective tissue.
3.5 OrganThe organ is consisted of cells of different tissues organized so that they can perform a complex, higher biological function. The heart, for example, contains a connective tissue “skeleton” in the shape of four rings that the heart muscle fibers attach to. The latter form four cavities that are covered internally by epithelial tissue, the endocardium. Externally, the entire heart muscle is covered by a double-walled epithelial sac, the pericardium. Within the walls of the heart there is its electrical conduction system, consisted of specialized cells that behave as both muscle and nervous tissue, which regulates the contraction of the muscle fibers. Thus, the heart functions as a pump, propelling forward the blood that enters it.
3.6 Organ system
3.7 OrganismThe organism is an individual, contiguous living system. It can be either uni- or multicellular. On the occasion of complex life forms, the organism is a set of organ systems that cooperate for the formation of an autonomous life form.
3.8 PopulationA group of organisms that belong to the same species.
3.9 CommunityA group of interacting organisms of different species that share the same environment.
3.10 EcosystemA community along with the inorganic matter (soil, water, air etc) of its environment.
3.11 BiosphereIt’s the set of all the ecosystems of the Earth (or another populated planet). Therefore, it also represents the zone of life on Earth.
4. Cosmic dust
It is a small collection of molecules that floats into space.
Dust particles, under the influence of gravity, attract each other and accumulate forming accretions.
An accretion can be organized in a well formed celestial body. Stars are big spherical luminous celestial bodies, which produce their own light and heat. Planets are bodies that orbit a star and have enough mass so that they can obtain a spherical shape. They do not transmit their own light and heat but receive these from their star. The planet we inhabit is the Earth and the star it orbits is the Sun. There are other celestial bodies, as well, such as asteroids and satellites.
It is consisted of a star along with the planets and the rest of the celestial bodies that are under the influence of its gravitational field. The star system of our Sun is called Solar system.
8. Star cluster
It is a group of stars, from tens to several millions, that are held together by the mutual gravitational forces. All the stars of a star cluster were born around the same period of time from the same cosmic dust, and each one has its own star system, with its planets, asteroids etc.
A system of millions or billions of star systems and clusters that are held together by gravitational forces forms a galaxy. The galaxy in which our solar system is found is the Milky way.
10. Galaxy cluster
A group of galaxies (from a few to a few thousands) that are held together by gravity comprise a galaxy cluster.
All of the existent spacetime, along with all of the matter and energy that it contains, constitute the Universe.
Explore the various levels in this wonderful interactive animation: The Scale of the Universe
Explore the various levels in this wonderful interactive animation: The Scale of the Universe
|1a. Elementary subatomic particles included in the Standard Model.|
Source: Wikipedia, Elementary particle
|1b. A proton is a composite particle|
consisting of two up and one down quarks.
Source: Wikipedia, Proton
|2. An illustration of the Helium atom, depicting the nucleus (pink)|
and the electron cloud distribution (black).
Source: Wikipedia, Atom
3. A water molecule is made of two hydrogen and one oxygen atoms.
|3.1. DNA (deoxyribonucleic acid) is a type a nucleic acid that encodes the genetic information for the development and functioning of all known living organisms and many viruses. Here is depicted the structure of the double helix of the DNA. On the right, you can see the four monomers of the DNA, T, A, C, G.|
Source: Wikipedia, DNA
|3.2 Electron microscopy of two mitochondria from mammalian lung tissue.|
Source: Wikipedia, Mitochondrion
|3.3. The basic components of an animal cell.|
Source: Wikipedia, Cell (biology)
|3.4. The different types of the muscle tissue.|
Source: Wikipedia, Muscle tissue
|3.5. The human heart.|
Source: Wikipedia, Heart
|3.6. The human circulatory system.|
Source: Wikipedia, Circulatory system
|3.7. All organisms are classified in groups (from domains to species) based on their evolutionary relationships. Here is a speculative phylogenetic tree of life of all existent organisms based on genetic analysis. Bacteria and archea are all unicellular, while the eukaryotes range from unicellular (such as the protozoan amoebas) to multicellular (such as all the plants and animals, including humans).|
Source: Wikipedia, Organism
|3.8. Map of population trends of jellyfish. Red: increase (high certainty),|
yellow: increase (low certainty), green: stable/variable, blue: decrease, gray: no data.
Source: Wikipedia, Population dynamics
|3.9. Predation is an interspecific interaction basic to community ecology.|
Source: Wikipedia, Community (ecology)
|3.10. Nitrogen cycling in an ecosystem, containing bacteria, fungi, plants,|
plant eating animals, along with inorganic materials, such as air and soil.
Source: Wikipedia, Ecosystem
|3.11. This composite image gives an indication of the magnitude and distribution|
of global primary production (the production of organic matter
from inorganic carbon sources) both oceanic and terrestrial.
Source: Wikipedia, Biosphere
|4. An interplanetary dust particle.|
Source: Wikipedia, Cosmic dust
|5. Artist's conception of a black hole drawing matter|
from a nearby star , forming an accretion disc.
Source: Wikipedia, Accretion disk
|6. Celestial bodies of our Solar System, including the Sun, the planets, asteroids etc.|
Source: Wikipedia, Solar System model
|7. The orbits of the bodies in the Solar System to scale|
(clockwise from top left)
Source: Wikipedia, Solarsystem
|10. The Abell S740 galaxy cluster.|
Source: Wikipedia, Abell_S740
|11. Illustration of the Big bang theory, the prevailing cosmological model. In this diagram time increases from left to right, and one dimension of space is suppressed, so at any given time the Universe is represented by a disk-shaped "slice" of the diagram.|
Source: Wikipedia, Universe