Difference between revisions of "Cellular biology" - New World Encyclopedia

Revision as of 03:11, 3 February 2007

Cell biology or cellular biology (formerly cytology, from the Greek kytos, "container") is an academic discipline that studies cells, including their physiological properties, structure, organelles, environmental interactions, life cycle, division, and death.

The ojbect of cell biology, a cell is the structural and functional unit of all living organisms and is sometimes called the "building block of life" (Alberts 2002). Some organisms, such as bacteria, are unicellular, consisting of a single cell. Other organisms, such as humans, are multicellular.

Cell biology is done both on a microscopic and molecular level, and extends to both single-celled organisms and the many specialized cells in multicellular organisms.

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.

Understanding cells in terms of their molecular components.

Origins of cell biology

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

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

References
ISBN links support NWE through referral fees

This article contains material from the Science Primer published by the NCBI, which, as a US government publication, is in the public domain at http://www.ncbi.nlm.nih.gov/About/disclaimer.html.

Immunohistochemistry - In Situ Hybridization
Nature Reviews Molecular Cell Biology (journal home)
The Virtual Library of Biochemistry and Cell Biology
Cell & Developmental Biology, Vanderbilt

Online cell biology textbooks

Molecular Biology of the Cell fourth edition, edited by Bruce Alberts (2002) published by Garland Science.
Molecular Cell Biology fourth edition, edited by Harvey Lodish (2000) published by W. H. Freeman and Company.
The Cell - A Molecular Approach second edition, by Geoffrey M. Cooper (2000) published by Sinauer Associates.
MIT Hypertext Cell Biology

General subfields within Biology
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Credits

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@@ Line 1: / Line 1: @@
 {{Contracted}}
-'''Cell biology''' or '''cellular biology''' (formerly '''cytology''', from the [[Greek language|Greek]] ''kytos'', "container") is an academic discipline that studies [[cell (biology)|cell]]s. This includes their [[physiology|physiological]] properties, their structure, the [[organelles]] they contain, interactions with their environment, their [[cell cycle|life cycle]], [[cell division|division]] and [[apoptosis|death]].
+'''Cell biology''' or '''cellular biology''' (formerly '''cytology''', from the [[Greek language|Greek]] ''kytos'', "container") is an academic discipline that studies [[cell (biology)|cell]]s, including their [[physiology|physiological]] properties, structure, [[organelles]], environmental interactions, life cycle, [[cell division|division]], and death.
-A cell is ..
+The ojbect of cell biology, a '''cell''' is the structural and functional unit of all living organisms and is sometimes called the "building block of [[life]]" (Alberts 2002). Some organisms, such as [[bacteria]], are unicellular, consisting of a single cell. Other organisms, such as [[human]]s, are multicellular.
-Cell biology is done both on a [[microscope|microscopic]] and [[molecule|molecular]] level, and extends to both the great diversity of single-celled organisms like [[bacterium|bacteria]] and the many specialized cells in multicellular [[organisms]] like [[human]]s.
+Cell biology is done both on a [[microscope|microscopic]] and [[molecule|molecular]] level, and extends to both single-celled organisms and the many specialized cells in multicellular [[organisms]].
-Knowing the composition of cells and how cells work is [[fundamental]] to all of the [[biology|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.
+Knowing the composition of cells and how cells work is fundamental to all of the [[biology|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]].
+Research in cell biology is closely related to [[genetics]], [[biochemistry]], [[molecular biology]], and [[developmental biology]].
 [[Image:NIEHScell.jpg|thumb|right|300px|Understanding cells in terms of their molecular components.]]
+==Origins of cell biology==
-Notes: The '''cell''' is the structural and functional unit of all living organisms and is sometimes called the "building block of [[life]]" (Alberts 2002). Some organisms, such as [[bacteria]], are unicellular, consisting of a single cell. Other organisms, such as [[human]]s, are multicellular. Humans have an estimated 100 trillion or 10<sup>14</sup> cells; a typical cell size is 10&nbsp;µm, a typical cell mass 1&nbsp;nanogram. The largest known cell is an [[ostrich]] [[egg (biology)|egg]].
-All living organisms, with the exception of [[virus]]es (and there is debate whether or not they can be considered living organisms), consist of cells, demonstrating the unity, harmony, and interconnectedness of life.
-The word ''cell'' comes from the [[Latin]] ''cellula'', a small room.  The name was chosen by [[Robert Hooke]] when he compared the cork cells he saw to the small rooms monks lived in.

Difference between revisions of "Cellular biology" - New World Encyclopedia

Revision as of 03:11, 3 February 2007

Contents

Origins of cell biology