Outline of cell biology

A branch of science

• Branch of science - A systematic enterprise that builds and organizes knowledge in the form of testable explanations and predictions about the universe.
• * Branch of natural science - The branch of science concerned with the description, prediction, and understanding of natural phenomena based on observational and empirical evidence. Validity, accuracy, and social mechanisms ensuring quality control, such as peer review and repeatability of findings, are among the criteria and methods used for this purpose.
• ** Branch of biology - The study of life and living organisms, including their structure, function, growth, evolution, distribution, and taxonomy.
• Academic discipline - Focused study in one academic field or profession. A discipline incorporates expertise, people, projects, communities, challenges, studies, inquiry, and research areas that are strongly associated with a given discipline.

  Essence of cell biology

• Cell - The structural and functional unit of all known living organisms. It is the smallest unit of an organism that is classified as living, and also known as the building block of life. Cell comes from the Latin cellula, meaning, a small room. Robert Hooke first coined the term in his book, Micrographia, where he compared the structure of cork cells viewed through his microscope to that of the small rooms of a monastery.
• Cell theory - The scientific theory which states that all organisms are composed of one or more cells. Vital functions of an organism occur within cells. All cells come from preexisting cells and contain the hereditary information necessary for regulating cell functions and for transmitting information to the next generation of cells.
• Cell biology - The study of cells.
• Cell division - The process of one parent cell separating into two or more daughter cells.
• Endosymbiotic theory - The evolutionary theory that certain eukaryotic organelles originated as separate prokaryotic organisms which were taken inside the cell as endosymbionts.
• Cellular respiration - The metabolic reactions and processes that take place in a cell or across the cell membrane to convert biochemical energy from fuel molecules into adenosine triphosphate and then release the cell's waste products.
• Lipid bilayer - A membrane composed of two layers of lipid molecules. The lipid bilayer is a critical component of the cell membrane.

  Aspects of cells

• Homeostasis - The property of either an open system or a closed system, especially a living organism, that regulates its internal environment so as to maintain a stable, constant condition.
• Life - A condition of growth through metabolism, reproduction, and the power of adaptation to environment through changes originating internally.
• Microscopic - The scale of objects, like cells, that are too small to be seen easily by the naked eye and which require a lens or microscope to see them clearly.
• Unicellular - Organisms which are composed of only one cell.
• Multicellular - Organisms consisting of more than one cell and having differentiated cells that perform specialized functions.
• Tissues - A collection of interconnected cells that perform a similar function within an organism.
• Cellular differentiation - A concept in developmental biology whereby less specialized cells become a more specialized cell type in multicellular organisms.

  Types of cells

• Cell type - Distinct morphological or functional form of cell. When a cell switches state from one cell type to another, it undergoes cellular differentiation. There are at least several hundred distinct cell types in the adult human body.

  By organism

• Eukaryote - Organisms whose cells are organized into complex structures enclosed within membranes, including plants, animals, fungi, and protists.
• * Animal cell - Eukaryotic cells belonging to kingdom Animalia, characteristically having no cell wall or chloroplasts.
• * Plant cell - Eukaryotic cells belonging to kingdom Plantae and having chloroplasts, cellulose cell walls, and large central vacuoles.
• *Fungal hypha - The basic cellular unit of organisms in kingdom fungi. Typically tubular, multinucleated, and with a chitinous cell wall.
• *Protist - A highly variable kingdom of eukaryotic organisms which are mostly unicellular and not plants, animals, or fungi.
• Prokaryote - A group of organisms whose cells lack a membrane-bound cell nucleus, or any other membrane-bound organelles, including bacteria.
• * Bacterial cells - A prokaryotic cell belonging to the mostly unicellular Domain Bacteria.
• * Archea cell - A cell belonging to the prokaryotic and single-celled microorganisms in Domain Archea.

  By function

• Gamete - A haploid reproductive cell. Sperm and ova are gametes. Gametes fuse with another gamete during fertilization in organisms that reproduce sexually.
• * Sperm - Male reproductive cell.
• * Ovum - Female reproductive cell.
• Zygote - A cell that is the result of fertilization.
• * Egg - The zygote of most birds and reptiles, resulting from fertilization of the ovum. The largest existing single cells currently known are eggs.
• Meristemic cell - Undifferentiated plants cells analogous to animal stem cells.
• Stem cell - Undifferentiated cells found in most multi-cellular organisms which are capable of retaining the ability to reinvigorate themselves through mitotic cell division and can differentiate into a diverse range of specialized cell types.
• Germ cell - Gametes and gonocytes, these are often. Germ cells should not be confused with "germs".
• Somatic cell - Any cells forming the body of an organism, as opposed to germline cells.
• '''more...'''

  General cellular anatomy

• Cellular compartment - All closed parts within a cell whose lumen is usually surrounded by a single or double lipid layer membrane.
• Organelles - A specialized subunit within a cell that has a specific function, and is separately enclosed within its own lipid membrane or traditionally any subcellular functional unit.

  Organelles

• Endomembrane system
• Endoplasmic reticulum - An organelle composed of an interconnected network of tubules, vesicles and cisternae.
• * Membrane bound polyribosome - Polyribosomes that are attached to a cell's endoplasmic reticulum.
• * Smooth endoplasmic reticulum - A section of endoplasmic reticulum on which ribosomes are not attached is termed as smooth endoplasmic reticulum. It has functions in several metabolic processes, including synthesis of lipids, metabolism of carbohydrates and calcium concentration, drug detoxification, and attachment of receptors on cell membrane proteins.
• * Rough endoplasmic reticulum - A section of the endoplasmic reticulum on with the protein manufacturing organelle i.e. ribosomes are attached is termed as rough endoplasmic reticulum which give it a "rough" appearance. Its primary function is the synthesis of enzymes and other proteins.
• * Vesicle - A relatively small intracellular, membrane-enclosed sac that stores or transports substances.
• * Golgi apparatus - A eukaryotic organelle that processes and packages macromolecules such as proteins and lipids that are synthesized by the cell.
• Nuclear envelope - It is the double lipid bilayer membrane which surrounds the genetic material and nucleolus in eukaryotic cells. The nuclear membrane consists of two lipid bilayers:
• * Inner nuclear membrane
• * Outer nuclear membrane
• * Perinuclear space - Space between the nuclear membranes, a region contiguous with the lumen of the endoplasmic reticulum. The nuclear membrane has many small holes called nuclear pores that allow material to move in and out of the nucleus.
• Lysosomes - It is a membrane-bound cell organelle found in most animal cells. Structurally and chemically, they are spherical vesicles containing hydrolytic enzymes capable of breaking down virtually all kinds of biomolecules, including proteins, nucleic acids, carbohydrates, lipids, and cellular debris. lysosomes act as the waste disposal system of the cell by digesting unwanted materials in the cytoplasm, both from outside of the cell and obsolete components inside the cell. For this function they are popularly referred to as "suicide bags" or "suicide sacs" of the cell.
• Endosomes - It is a membrane-bounded compartment inside eukaryotic cells. It is a compartment of the endocytic membrane transport pathway from the plasma membrane to the lysosome. Endosomes represent a major sorting compartment of the endomembrane system in cells.
• Cell nucleus - A membrane-enclosed organelle found in most eukaryotic cells. It contains most of the cell's genetic material, organized as multiple long linear DNA molecules in complex with a large variety of proteins, such as histones, to form chromosomes.
• * Nucleoplasm - Viscous fluid, inside the nuclear envelope, similar to cytoplasm.
• * Nucleolus - Where ribosomes are assembled from proteins and RNA.
• * Chromatin - All DNA and its associated proteins in the nucleus.
• * Chromosome - A single DNA molecule with attached proteins.
• Energy creators
• * Mitochondrion - A membrane-enclosed organelle found in most eukaryotic cells. Often called "cellular power plants", mitochondria generate most of cells' supply of adenosine triphosphate, the body's main source of energy.
• * Chloroplast - An organelles found in plant cells and eukaryotic algae that conduct photosynthesis.
• Centrosome - The main microtubule organizing center of animal cells as well as a regulator of cell-cycle progression.
• Lysosome - The organelles that contain digestive enzymes. They digest excess or worn-out organelles, food particles, and engulfed viruses or bacteria.
• Peroxisome - A ubiquitous organelle in eukaryotes that participates in the metabolism of fatty acids and other metabolites. Peroxisomes have enzymes that rid the cell of toxic peroxides.
• Ribosome - It is a large and complex molecular machine, found within all living cells, that serves as the site of biological protein synthesis. Ribosomes build proteins from the genetic instructions held within messenger RNA.
• Symbiosome - A temporary organelle that houses a nitrogen-fixing endosymbiont.
• Vacuole - A membrane-bound compartments within some eukaryotic cells that can serve a variety of secretory, excretory, and storage functions.