What is cell biology?

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Cell biology (also called cellular biology or formerly cytology, from the Greek kytos, "container") is an academic discipline that studies cells. This includes 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 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.

Processes

 Movement of proteins

 

Proteins (red and green stain) at different locations in a cell.Every cell typically contains hundreds of different kinds of macromolecules that function together to generate the behavior of the cell. Each type of protein is usually sent to a particular part of the cell. An important part of cell biology is investigation of molecular mechanisms by which proteins are moved to different places inside cells or secreted from cells.

Most proteins are synthesized by ribosomes in the cytoplasm. This process is also known as protein biosynthesis or simply protein translation. Some proteins, such as those to be incorporated in membranes (membrane proteins), are transported into the ER during synthesis and further processed in the Golgi apparatus. From the Golgi, membrane proteins can move to the plasma membrane, to other subcellular compartments or they can be secreted from the cell. The ER and Golgi can be thought of as the "membrane protein synthesis compartment" and the "membrane protein processing compartment", respectively. There is a semi-constant flux of proteins through these compartments. ER and Golgi-resident proteins associate with other proteins but remain in their respective compartments. Other proteins "flow" through the ER and Golgi to the plasma membrane. Motor proteins transport mebrane protein-containing vesicles along cytoskeletal tracks to distant parts of cells such as axon terminals.

Some proteins that are made in the cytoplasm contain structural features that target them for transport into mitochondria or the nucleus. Some mitochondrial proteins are made inside mitochondria and are coded for by mitochondrial DNA. In plants, chloroplasts also make some cell proteins.

Extracellular and cell surface proteins destined to be degraded can move back into intracellular compartments upon being incorporated into endocytosed vesicles. Some of these vesicles fuse with (lysosomes) where the proteins are broken down to their individual amino acids. The degradation of some membrane proteins begins while still at the cell surface when they are cleaved by secretases. Proteins that function in the cytoplasm are often degraded by proteasomes.

              Other cellular processes

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

Autophagy - The process whereby cells "eat" their own internal components or microbial invaders.

Techniques

 

Microscopy and Immunostaining

Gene knockdown and Transfection

Cell culture and Radioactive tracers

PCR and In situ hybridization

DNA microarray screens of gene expression

 Purification of cells and their parts

Purification of cells and their parts is achieved in the following ways:

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

 Some structures inside cells

 

Electronmicrograph.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
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Cell biology is the science of studying how cells function such as their reproduction and metabolism, their internal and external anatomy.

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Cell biology (also called cellular biology or formerly cytology, from the Greek kytos, "container") is an academic discipline that studies cells. This includes 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 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.
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Cell biology incorporates three historically distinct strands of biology - cytology (cell structure), biochemistry (cell function) and genetics.  These areas are closely related and cross inform each other.  Thus a modern cell biologist must have a good knowledge of all three disciplines.
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It's all about cells.... that includes 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.
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Cell biology (also called cellular biology or cytology, from the Greek kytos, "container") is an academic discipline which studies cells. This includes their physiological properties such as their structure and the organelles they contain, their environment and interactions, their life cycle, division and function (physiology) and eventual death.
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cell biology is that in which we can study about cell, its function, its structure, by cell biology we can study about the theory of cell.

how these cell originated,how can they funtion at different place
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The study of the activities, functions, properties, and structures of cells. Cells were discovered in the middle of the seventeenth century after the microscope was invented. In the following two centuries, with steadily improved microscopes, cells were studied in a wide variety of plants, animals, and microorganisms, leading to the discovery of the cell nucleus and several other major cell parts. By the 1830s biologists recognized that all organisms are composed of cells, a realization that is now known as the Cell Doctrine. The Cell Doctrine constitutes the first major tenet upon which the contemporary science of cell biology is founded. By the late 1800s biologists had established that cells do not arise de novo, but come only by cell division, that is, division of a preexisting cell into two daughter cells. This is the second major tenet upon which the modern study of cells is based. See also Microscope.

By the end of the nineteenth century chromosomes had been discovered, and biologists had described mitosis—the distribution at cell division of chromosomes to daughter cells. Subsequent studies showed that the chromosomes contain genes and that mitosis distributes a copy of every chromosome and hence every gene to each daughter cell during cell division. This established the basis of cell heredity and ultimately the basis of heredity in multicellular organisms. See also Chromosome; Mitosis.

Microscope studies established that some kinds of organisms are composed of a single cell and some, such as plants and animals, are made up of many cells—usually many billions. Unicellular organisms are the bacteria, protozoa, some fungi, and some algae. All other organisms are multicellular. An adult human, for example, consists of about 200 cell types that collectively amount to more than 1014 cells.

All modern research recognizes that in both unicellular and multicellular organisms the cell is the fundamental unit, housing the genetic material and the biochemical organization that account for the existence of life. Many millions of different species of cells exist on Earth. Cells as different as a bacterium, an ameba, a plant leaf cell, and a human liver cell appear to be so unrelated in structure and life-style that they might seem to have little in common; however, the study of cells has shown that the similarities among these diverse cell types are more profound than the differences. These studies have established a modern set of tenets that bring unity to the study of many diverse cell types. These tenets are: (1) All cells store information in genes made of deoxyribonucleic acid (DNA). (2) The genetic code used in the genes is the same in all species of cells. (3) All cells decode the genes in their DNA by a ribonucleic acid (RNA) system that translates genetic information into proteins. (4) All cells synthesize proteins by using a structure called the ribosome. (5) Proteins govern the activities, functions, and structures in all cells. (6) All cells need energy to operate; all use the molecule adenosine triphosphate (ATP) as the currency for transfer of energy from energy sources to energy needs. (7) All cells are enclosed by a plasma membrane composed of lipid and protein molecules. See also Genetics; Ribosomes.

In the twentieth century the study of cells, which had been dominated for more than 200 years by microscopy, has been enormously expanded with many other experimental methods. The breaking open of a large mass of cells and the separation of released cell parts into pure fractions led to the discovery of functions contributed by different structures and organelles.

Contemporary research in cell biology is concerned with many problems of cell operation and behavior. Cell reproduction is of special concern because it is essential for the survival of all unicellular and multicellular forms of life. Cell reproduction is the means by which a single cell, the fertilized egg, can give rise to the trillions of cells in an adult multicellular organism. Disrupted control of cell reproduction, resulting in accumulation of disorganized masses of functionally useless cells, is the essence of cancer. Indeed, all diseases ultimately result from the death or misfunctioning of one or another group of cells in a plant or animal. The study of cells pervades all areas of medical research and medical treatment. Great advances have been made in learning how cells of the immune system combat infection, and the nature of their failure to resist the acquired immune deficiency syndrome (AIDS) virus. See also Acquired immune deficiency syndrome (AIDS); Cancer (medicine); Cell senescence and death.

The development of methods to grow plant and animal cells in culture has provided new ways to study cells free of the experimental complications encountered with intact plants and animals. Cell culture has greatly facilitated analysis of abnormal cells, including transformation of normal cells into cancer cells. Cultured cells are also used extensively to study cell differentiation, cell aging, cell movement, and many other cell functions. See also Tissue culture.
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