INTRODUCTION TO GENERAL BIOLOGY
What is life?
When we want to learn, we must ask ourselves so many question and try to answer these.
What will be the first question? It will be, What is Biology?
Biology studies all living organisms. Biology literally means "the study of life".
Living things have a variety of common characteristics. These are:
1. Organization
2. Energy use and metabolism
3. Maintenance of internal constancy, that it is called Homeostasis.
4. Reproduction, Growth and Development
5. Irritability and Adaptation, that it is the response to environment.
Organization: Living things exhibit a high level of organization, with multicellular organisms being subdivided into cells, and cells into organelles, and organelles into molecules, etc.
Levels of biological organization include the relationships among organisms and their environment. These levels of biological organization are:
Biosphere, Ecosystem, Community, Population, Organism, Organ, Tissue, Cell, Organelle, Molecule and Atom.
Biosphere means the sum of all living matter on Earth.
Ecosystem is the community living in an area and its physical environment.
Community is the relationships between groups of different species.
Population is a group of individuals of the same species living in the same area at the same time and sharing a common gene pool.
Organism is an individual, composed of organ systems (if it is multicellular).
Organ is a group of cells or tissues performing an overall function.
Tissue is a group of cells performing a specific function.
Cell is The fundamental unit of living things.
Organelle is A subunit of a cell, it is involved in a specific subcellular function.
Molecule is Units of two or more atoms held together by chemical bonds.
Atom is The smallest indivisible particle of matter that can have an independent existence.
Parts of the planet and its atmosphere where life is possible is the biosphere.
The living and nonliving environment is the ecosystem. It includes all organisms, plus soil, rocks, water, etc.
All organisms in a given place and time is community.
A group of the same type of organism living in the same place and time is a population.
One or more cells characterized by a unique arrangement of DNA "information" is an organism. These can be unicellular or multicellular. The multicellular individual exhibits specialization of cell types and division of labor into tissues, organs, and organ systems.
In multicellular organisms, A group of cells or tissues performing an overall function is an organ like brain.
A collection of specialized cells and the substances they secrete that function in a coordinated fashion is a tissue. For example the nervous ganglion who its function is the transmission of the nervous impulses.
Each cell has some sort of hereditary material (either DNA or more rarely RNA), energy acquiring chemicals, structures, etc.
An organelle is involved in a specific subcellular function, for example the ribosome is the site of protein synthesis, or mitochondrion is the site of ATP generation in eukaryotes.
Molecules, atoms, and subatomic particles are the fundamental functional levels of Biochemistry.
Biochemistry is the Chemical processes associated with living things.
One view of life is that it is a struggle to acquire energy (from sunlight, inorganic chemicals, or another organism), and release it in the process of forming ATP (adenosine triphosphate).
An organism must be able to acquire and use energy to build new structures, repair or break down old ones, and reproduce.
Organisms obtain energy to carry out life processes from the environment.
Producers, also called autotrophos, are organisms that extract energy from the nonliving environment, such as plant capturing light energy from the sun.
Consumers, also called heterotrophs, in contrast, obtain energy by eating nutrients that make up other organisms.
Descomposers are consumers that obtain nutrients from dead organisms. Fungi, such as mushrooms, are descomposers.
The term metabolism refers to the chemical reactions within cells that maintain life.
Homeostasis is the ability to maintain a relatively constant internal environment in terms of temperature, pH, water concentrations, etc.
For example, a cell must maintain a certain temperature and water balance. It must take in nutrients, excrete wastes and regulate its many chemical reactions to prevent deficiencies or excesses of specific substances.
Since all cells come from existing cells, they must have some way of reproducing. Reproduction occurs in two basic ways:
In asexual reproduction, cellular contents double, then the cell divides to form two new individuals that are genetically identical to the original parent cell like the bacterium Escherichia coli.
In sexual reproduction, genetic material from two individuals join to form a third individual, which has a new combination of inherited traits.
Living organisms sense and respond to certain environmental stimuli while ignoring others.
Irritability is the tendency to respond immediately to stimuli, and it can be essential for survival.
In contrast, an adaptation is a response that develops over time, and It is the tendency of an organism to suit its environment.
Charles Darwin began the recognition of the marvelous adaptations all life has that allow those organisms to exist in their environment.
Those organisms best adapted will have a greater chance of surviving and passing their genes on to the next generation. This is knowing like Natural selection.
Evolutionary theory and the cell theory provide us with a basis for the interrelation of all living things. We also utilize Linneus' hierarchical classification system to classify organisms.
There are three Domains: Archaea, Bacteria and Eukarya. Basic differences in cellular constituents and organization distinguish the domains.
The most primitive group, the Archaebacteria, are today restricted to marginal habitats such as hot springs or areas of low oxygen concentration. Some biologists want to place this group into a separate Kingdom, the Archaea. Most currently place it within the Kingdom Monera.
Monera prokaryotic kingdom that includes (in the most widely accepted classification system) archaebacteria, eubacteria and cyanobacteria. Members of this kingdom were among the first forms of life over 3.5 billion years ago.
Bacteria (Eubacteria) and Archaea differ in their chemistry.
Protista were the first of the eukaryotic kingdoms, these organisms and all others have membrane-bound organelles, which allow for compartmentalization and dedication of specific areas for specific functions. The chief importance of Protista is their role as a stem group for the remaining Kingdoms: Plants, Animals, and Fungi.
Prokaryotic cell is a type of cell that lacks a
membrane-bound nucleus and has no membrane
organelles.
Eukaryotic cell is A type of cell characterized by a membrane-bounded nucleus and other membraneous organelles.
Taxonomy is that branch of biology dealing with the identification and naming of organisms.
Linnean hierarchical classification is based on the premise that the species are the smallest unit, and that each species or taxon, nest within a higher category.
An organism is assigned to a specific domain, kingdom, division or phylum, class, order, family, genus and species.
Domain: cells with similarity in cellular constituents and organization.
Kingdoms: taxonomic categories into which organisms are grouped, based on common characteristics.
Phylum: the broadest taxonomic category within kingdoms.
Class: subcategories of phyla.
Order: subcategories of classes.
Family: subcategories within orders.
Genera: subcategories within families
(sing.: genus), composed of one or more species.
Species: Populations of individuals capable of interbreeding and producing viable, fertile offspring.
Linneus also developed the concept of binomial nomenclature, whereby scientists speaking and writing different languages could communicate clearly. For example, a human is Homo sapiens.
Moss rose belongs to Kingdom Plantae, Phylum Tracheophyta, Class Angiospermae, Order Rosales, Family Rosaceae, Genus Rosa and Specie Rosa gallica.