Immunology in the context of "Human variability"

Cell biology, cellular biology, or cytology, is the branch of biology that studies the structure, function, and behavior of the cells. All organisms are made of cells. A cell is the basic unit of life that is responsible for the living and functioning of an organism. Cell biology encompasses both prokaryotic and eukaryotic cells, with subtopics including the study of cell metabolism, cell communication, cell cycle, biochemistry, and cell composition.

The study of cells is performed using microscopy techniques, cell culture, and cell fractionation. These are used for research into how cells function, which ultimately gives insight into larger organisms. Knowing the components of cells and how cells work is fundamental to all biological sciences and is essential for research in biomedical fields such as cancer, and other diseases. Research in cell biology is interconnected to other fields such as genetics, molecular genetics, molecular biology, medical microbiology, immunology, and cytochemistry.

This list of life sciences comprises the branches of science that involve the scientific study of life — such as animals (including human beings), microorganisms, and plants. This is one of the two major branches of natural science, the other being physical science, which is concerned with non-living matter. Biology is the overall natural science that studies life, with the other life sciences as its sub-disciplines.

Some life sciences focus on a specific type of organism. For example, zoology is the study of animals, while botany is the study of plants. Other life sciences focus on aspects common to all or many life forms, such as anatomy and genetics. Some focus on the micro scale (e.g., molecular biology, biochemistry), while others focus on larger scales (e.g., cytology, immunology, ethology, pharmacy, ecology). Another major branch of life sciences involves understanding the mind—neuroscience. Life-science discoveries are helpful in improving the quality and standard of life and have applications in health, agriculture, medicine, and the pharmaceutical and food science industries. For example, they have provided information on certain diseases, which has helped in the understanding of human health.

A cell type is a classification used to identify cells that share morphological or phenotypical features. A multicellular organism may contain cells of a number of widely differing and specialized cell types, such as muscle cells and skin cells, that differ both in appearance and function yet have identical genomic sequences. Cells may have the same genotype, but belong to different cell types due to the differential regulation of the genes they contain. Classification of a specific cell type is often done through the use of microscopy (such as those from the cluster of differentiation family that are commonly used for this purpose in immunology). Recent developments in single cell RNA sequencing facilitated classification of cell types based on shared gene expression patterns. This has led to the discovery of many new cell types in e.g. mouse grey matter, hippocampus, dorsal root ganglion and spinal cord.

Animals have evolved a greater diversity of cell types in a multicellular body (100–150 different cell types), comparedwith 10–20 in plants, fungi, and protists. The exact number of cell types is, however, undefined, and the Cell Ontology, as of 2021, lists over 2,300 different cell types.

Microbiology (from Ancient Greek μῑκρος (mīkros) 'small' βίος (bíos) 'life' and -λογία (-logía) 'study of') is the scientific study of microorganisms, those being of unicellular (single-celled), multicellular (consisting of complex cells), or acellular (lacking cells). Microbiology encompasses numerous sub-disciplines including virology, bacteriology, protistology, mycology, immunology, and parasitology.

The organisms that constitute the microbial world are characterized as either prokaryotes or eukaryotes; Eukaryotic microorganisms possess membrane-bound organelles and include fungi and protists, whereas prokaryotic organisms are conventionally classified as lacking membrane-bound organelles and include Bacteria and Archaea. Microbiologists traditionally relied on culture, staining, and microscopy for the isolation and identification of microorganisms. However, less than 1% of the microorganisms present in common environments can be cultured in isolation using current means. With the emergence of biotechnology, Microbiologists currently rely on molecular biology tools such as DNA sequence-based identification, for example, the 16S rRNA gene sequence used for bacterial identification.

Alexandre Émile John Yersin (22 September 1863 – 1 March 1943) was a Swiss-French physician and bacteriologist. He is remembered for his work as a pioneer in microbiology and immunology. Yersin is the co-discoverer of both the Diphtheria and Tetanus toxins (1890 with Émile Roux) and of the bacillus responsible for the bubonic plague or pest (1894, with Kitasato Shibasaburō). The bacteria was later named in his honour: Yersinia pestis. Yersin also demonstrated for the first time that the same bacillus was present in the rodent as well as in the human disease, thus underlining the possible means of transmission.