Biology (from Greek: βίος, bio, "life"; and λόγος, logos, "speech" lit. "to talk about life") , also referred to as the biological sciences, is the scientific study of life. Biology examines the structure, function, growth, origin, evolution, and distribution of living things. It classifies and describes organisms, their functions, how species come into existence, and the interactions they have with each other and with the natural environment. Four unifying principles form the foundation of modern biology: cell theory, evolution, genetics and homeostasis.

Biology as a separate science was developed in the nineteenth century, as scientists discovered that organisms shared fundamental characteristics. Biology is now a standard subject of instruction at schools and universities around the world, and over a million papers are published annually in a wide array of biology and medicine journals.

Most biological sciences are specialized disciplines. Traditionally, they are grouped by the type of organism being studied: botany, the study of plants; zoology, the study of animals; and microbiology, the study of microorganisms. The fields within biology are further divided based on the scale at which organisms are studied and the methods used to study them: biochemistry examines the fundamental chemistry of life; molecular biology studies the complex interactions of systems of biological molecules; cellular biology examines the basic building block of all life, the cell; physiology examines the physical and chemical functions of the tissues and organ systems of an organism; and ecology examines how various organisms and their environment interrelate.

Zoology is the biological discipline which involves the study of animals. It is the study of animals. Zoology is not concerned only with the study of the animals that are living on earth at present time but also those which lived in the past and has disappeared or has become extinct.

Morphology:  This term is used for the study of the from and structure of animals.

Anatomy:  It deals with the structure of animals more especially as revealed by dissection.

Histology:  It is the study of minute details of structure with the aid of the microscope.

Physiology:  Physiology describes the bodily functions.

Embryology:  It describes the development of an animal from the egg to the adult.

Taxonomy:  It deals with the classification of animal into group.

Ecology:  It is the study of the relation of an animal on of surface pf the animals.

Paleo-fossile:  It is the study of the relation of an animal on of extinct animals.

Heredity:  It is concerned with the transmission of character from parents to offspring.

Evolution:  It deals with the origin and differentiation of a animals from pre-exiting ones.

Botany is the scientific study of plant life. As a branch of biology, it is also called plant science(s), phytology, or plant biology. Botany covers a wide range of scientific disciplines that study plants, algae, and fungi including: structure, growth, reproduction, metabolism, development, diseases, and chemical properties and evolutionary relationships between the different groups. The study of plants and botany began with tribal lore, used to identify edible, medicinal and poisonous plants, making botany one of the oldest sciences. From this ancient interest in plants, the scope of botany has increased to include the study of over 550,000 kinds or species of living organisms.

In biology, evolution is the changes seen in the inherited traits of a population from one generation to the next. These changes cause populations of organisms to change over time. Inherited traits come from the genes that are passed on to offspring during reproduction. Mutations in genes can produce new or altered traits, resulting in the appearance of heritable differences between organisms. Such new traits also come from the transfer of genes between populations, as in migration, or between species, in horizontal gene transfer. Evolution occurs when these heritable differences become more common or rare in a population, either non-randomly through natural selection or randomly through genetic drift.

Ecology (from Greek: οίκος, oikos, "household"; and λόγος, logos, "knowledge") is the scientific study of the distribution and abundance of life and the interactions between organisms and their environment. The environment of an organism includes physical properties, which can be described as the sum of local abiotic factors such as insolation (sunlight), climate, and geology, and biotic factors, which are other organisms that share its habitat.

The word "ecology" is often used more loosely in such terms as social ecology and deep ecology and in common parlance as a synonym for the natural environment or environmentalism. Likewise "ecologic" or "ecological" is often taken in the sense of environmentally friendly.

Biotechnology is technology based on biology, especially when used in agriculture, food science, and medicine. The United Nations Convention on Biological Diversity defines biotechnology as:

"Biotechnology" means any technological application that uses biological systems, living organisms, or derivatives thereof, to make or modify products or processes for specific use."

Biotechnology is often used to refer to genetic engineering technology of the 21st century, however the term encompasses a wider range and history of procedures for modifying biological organisms according to the needs of humanity, going back to the initial modifications of native plants into improved food crops through artificial selection and hybridization. Bioengineering is the science upon which all Biotechnological applications are based. With the development of new approaches and modern techniques, traditional biotechnology industries are also acquiring new horizons enabling them to improve the quality of their products and increase the productivity of their systems.

• Medicine
• Pharmacogenomics
• Pharmaceutical products
• Genetic testing
• Gene therapy
• Human Genome Project
• Cloning
• Agriculture
• Improve yield from crops
• Reduced vulnerability of crops to environmental stresses
• Increased nutritional qualities of food crops
• Improved taste, texture or appearance of food
• Reduced dependence on fertilizers, pesticides and other agrochemicals
• Production of novel substances in crop plants
• Biological engineering
• Bioremediation and Biodegradation

Genetics, a discipline of biology, is the science of heredity and variation in living organisms.Knowledge of the inheritance of characteristics has been implicitly used since prehistoric times for improving crop plants and animals through selective breeding. However, the modern science of genetics, which seeks to understand the mechanisms of inheritance, only began with the work of Gregor Mendel in the mid-1800s. Although he did not know the physical basis for heredity, Mendel observed that inheritance is fundamentally a discrete process with specific traits that are inherited in an independent manner these basic units of inheritance are now called genes.

• History of genetics
• Mendelian and classical genetics
• Molecular genetics
• Features of inheritance
• Discrete inheritance and Mendel's laws
• Assortment and interactions of multiple genes
• The molecular basis for inheritance
• DNA and chromosomes
• Reproduction
• Genetic recombination and linkage
• Gene expression and the creation of phenotype
• The genetic code
• Nature vs. nurture
• Gene regulation
• Mutations and natural selection
• Mutations
• Natural selection and evolution
• Genetic research and technology
• Model organisms and genetics
• Medical genetics research
• Genetic technologies
• DNA sequencing & genomics

Cell biology (also called cellular biology or formerly cytology, from the Greek kytos, "container") is an academic discipline that studies cells their physiological properties, their structure, the organelles they contain, interactions with their environment, their life cycle, division and death. This is done both on a microscopic and molecular level. Cell biology research extends to both the great diversity of single-celled organisms like bacteria and the many specialized cells in multicellular organisms like humans.

Knowing the composition of cells and how cells work is fundamental to all of the biological sciences. Appreciating the similarities and also differences between cell types is particularly important to the fields of cell and molecular biology. These fundamental similarities and differences provide a unifying theme, allowing the principles learned from studying one cell type to be extrapolated and generalized to other cell types. Research in cell biology is closely related to genetics, biochemistry, molecular biology and developmental biology.

Cell division :  The origin of new cells.

Cell signaling:  Regulation of cell behavior by signals from outside.

Active transport and Passive transport :  Movement of molecules into and out of cells.

Adhesion :  Holding together cells and tissues.

Transcription and mRNA splicing :  gene expression.

Cell movement:  Chemotaxis, Contraction, cilia and flagella

DNA repair and Cell death

Metabolism:  Glycolysis, respiration, Photosynthesis .

Organelle :  term used for major subcellular structures

Chloroplast:  key organelle for photosynthesis

Cilia :  motile microtubule-containing structures of eukaryotes

Cytoplasm:  contents of the main fluid-filled space inside cells

Cytoskeleton:  protein filaments inside cells .

Ribosome:  RNA and protein complex required for protein synthesis in cells

Endoplasmic reticulum :  major site of membrane protein synthesis

Flagella:  motile structures of bacteria, archaea and eukaryotes

Golgi apparatus :  site of protein glycosylation in the endomembrane system

Membrane lipid and protein barrier

Lipid bilayer :  fundamental organizational structure of cell membranes .

Vesicle:  small membrane-bounded spheres inside cells.

Mitochondrion:  major energy-producing organelle

Nucleus:  holds most of the DNA of eukaryotic cells

• Cells may be observed under the microscope. This includes the Optical Microscope, Transmission Electron Microscope, Scanning Electron Microscope, Fluorescence Microscope, and by Confocal Microscopy.
• Immunostaining can also be imploded to observe cells. Such examples are:
• Gene knockdown and Transfection
• Cell culture and Radioactive tracers
• PCR and In situ hybridization
• DNA microarray screens of gene expression
• Computational genomics approaches are used to find patterns in genomic information
• Purification of cells and their parts
• Purification may be performed using the following methods:
• Flow cytometry
• Cell fractionation
• Release of cellular organelles by disruption of cells.
• Separation of different organelles by centrifugation.
• Proteins extracted from cell membranes by detergents and salts or other kinds of chemicals.
• Immunoprecipitation.

Biochemistry is the study of the chemical processes in living organisms. It deals with the structure and function of cellular components, such as proteins, carbohydrates, lipids, nucleic acids, and other biomolecules. Chemical biology aims to answer many questions arising from biochemistry by using tools developed within chemical synthesis.

Although there are a vast number of different biomolecules, many are complex and large molecules (called polymers) that are composed of similar repeating subunits (called monomers). Each class of polymeric biomolecule has a different set of subunit types. For example, a protein is a polymer made up of 20 or more amino acids. Biochemistry studies the chemical properties of important biological molecules, like proteins, in particular the chemistry of enzyme-catalyzed reactions.

The biochemistry of cell metabolism and the endocrine system has been extensively described. Other areas of biochemistry include the genetic code (DNA, RNA), protein synthesis, cell membrane transport, and signal transduction.

• Carbohydrates
• Monosaccharides
• Disaccharides
• DOligosaccharides and polysaccharides
• Use of carbohydrates as an energy source
• Glycolysis (anaerobic)
• Aerobic
• Gluconeogenesis
• Proteins
• Lipids
• Nucleic acids
• Relationship to other "molecular-scale" biological sciences

Molecular biology is the study of biology at a molecular level. The field overlaps with other areas of biology and chemistry, particularly genetics and biochemistry. Molecular biology chiefly concerns itself with understanding the interactions between the various systems of a cell, including the interactions between DNA, RNA and protein biosynthesis and learning how these interactions are regulated.

• Relationship to other "molecular-scale" biological sciences
• Techniques of molecular biology
• Expression cloning
• Polymerase chain reaction (PCR)
• Gel electrophoresis
• Southern blotting
• Northern blotting
• Western blotting
• Arrays
• Abandoned technology

Immunology is a broad branch of biomedical science that covers the study of all aspects of the immune system in all organisms. It deals with, among other things, the physiological functioning of the immune system in states of both health and disease; malfunctions of the immune system in immunological disorders (autoimmune diseases, hypersensitivities, immune deficiency, allograft rejection); the physical, chemical and physiological characteristics of the components of the immune system in vitro, in situ, and in vivo. Immunology has various applications in several disciplines of science, and as such is further divided.

• Histological examination of the immune system
• Classical immunology
• Clinical immunology
• Immunotherapy
• Diagnostic immunology
• Evolutionary immunology

Bioinformatics and computational biology involve the use of techniques including applied mathematics, informatics, statistics, computer science, artificial intelligence, chemistry, and biochemistry to solve biological problems usually on the molecular level. Research in computational biology often overlaps with systems biology. Major research efforts in the field include sequence alignment, gene finding, genome assembly, protein structure alignment, protein structure prediction, prediction of gene expression and protein-protein interactions, and the modeling of evolution.

• Sequence analysis
• Genome annotation
• Computational evolutionary biology
• Measuring biodiversity
• Analysis of gene expression
• Analysis of regulation
• Analysis of protein expression
• Analysis of mutations in cancer
• Prediction of protein structure
• Comparative genomics
• Modeling biological systems
• High-throughput image analysis
• Protein-protein docking

Recombinant DNA is a form of artificial DNA that is engineered through the combination or insertion of one or more DNA strands, thereby combining DNA sequences that would not normally occur together. In terms of genetic modification, recombinant DNA is produced through the addition of relevant DNA into an existing organismal genome, such as the plasmid of bacteria, to code for or alter different traits for a specific purpose, such as immunity. It differs from genetic recombination, in that it does not occur through processes within the cell or ribosome, but is exclusively engineered.

• Applications and methods
• Cloning and relation to plasmids
• Chimeric plasmids
• Synthetic insulin production using DNA

Microbiology is the study of microorganisms, which are unicellular or cell-cluster microscopic organisms. This includes eukaryotes such as fungi and protists, and prokaryotes such as bacteria and certain algae. Viruses, though not strictly classed as living organisms, are also studied. Microbiology is a broad term which includes many branches like virology, mycology, parasitology and others. A person who specializes in the area of microbiology is called a microbiologist.

Although much is now known in the field of microbiology, advances are being made regularly. We have probably only studied about 1% of all of the microbe species on Earth. Thus, despite the fact that over three hundred years have passed since the discovery of microbes, the field of microbiology could be said to be in its infancy relative to other biological disciplines such as zoology, botany and entomology.