Cytology

Information about Cytology

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.

Understanding cells in terms of their molecular components.

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 the 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 or endoplasmic reticulum 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 membrane 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
Computational genomics approaches are used to find patterns in genomic information ^[1]

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

1. ^ Cristianini, N. and Hahn, M. Introduction to Computational Genomics, Cambridge University Press, 2006. (ISBN-13: 9780521671910 | ISBN-10: 0521671914)

Wikiversity has learning resources related to this subject:

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.

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Agriculture and forestry

Agronomy
Animal science
Agrology
Environmental science
Agricultural economics
Aquaculture

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Physiology (from Greek: φυσις, physis, “nature, origin”; and λόγος, logos, "knowledge") is the study of the mechanical, physical, and biochemical functions of living organisms.
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In cell biology, an organelle is a specialized subunit within a cell, having a specific function, and separately enclosed within its own lipid membrane.

The name organelle
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The cell cycle, or cell-division cycle, is the series of events that take place in a eukaryotic cell leading to its replication. These events can be divided in two broad periods: interphase—during which the cell grows, accumulating nutrients needed for mitosis and
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Cell division is a process by which a cell, called the parent cell, divides into two cells, called daughter cells. Cell division is usually a small segment of a larger cell cycle. In meiosis however, a cell is permanently transformed and cannot divide again.
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Apoptosis (pronounced ă-pŏp-tŏ’sĭs, apo tō' sis) is a form of programmed cell death in multicellular organisms. It is one of the main types of programmed cell death (PCD), and involves an orchestrated series of biochemical events leading to a
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molecule is defined as a sufficiently stable electrically neutral group of at least two atoms in a definite arrangement held together by strong chemical bonds.^[1]^[2] In organic chemistry and biochemistry, the term molecule
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Bacteria

Phyla

Actinobacteria
Aquificae
Chlamydiae
Bacteroidetes/Chlorobi
Chloroflexi
Chrysiogenetes
Cyanobacteria
Deferribacteres
Deinococcus-Thermus
Dictyoglomi
Fibrobacteres/Acidobacteria
Firmicutes
Fusobacteria
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Plantae

Chromalveolata

Heterokontophyta

Haptophyta

Cryptophyta

Alveolata

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Biology (from Greek: βίος, bio, "life"; and λόγος, logos, "knowledge"), also referred to as the biological sciences, is the scientific study of life.
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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,
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The term moral obligation has a number of meanings in moral philosophy, in religion, and in layman's terms. Generally speaking, when someone says of an act that it is a "moral obligation," they refer to a belief that the act is one prescribed by their set of values.
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Genetics is the science of heredity and variation in living organisms.^[1]^[2] Knowledge of the inheritance of characteristics has been implicitly used since prehistoric times for improving crop plants and animals through selective breeding.
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Biochemistry is the study of the chemical processes in living organisms.^[1] The word "biochemistry" comes from the Greek word βιοχημεία biochēmeia, which means "the chemistry of life.
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Developmental Biology is the official journal of the Society for Developmental Biology. It publishes research on the mechanisms of development, differentiation, and growth in animals and plants at the molecular, cellular, and genetic levels.
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macromolecule implies large molecule. In the context of science and engineering, the term may be applied to conventional polymers and biopolymers (such as DNA) as well as non-polymeric molecules with large molecular mass such as lipids or macrocycles.
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Proteins are large organic compounds made of amino acids arranged in a linear chain and joined together by peptide bonds between the carboxyl and amino groups of adjacent amino acid residues.
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A ribosome is a small, dense, functional structure found in most known cells that assemble proteins and polypeptides used in cell division. It catalyses the assembly of individual amino acids into polypeptide chains by reading messenger RNAs and binding amino acids that are
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Cytoplasm is a gelatinous, semi-transparent fluid that fills most cells. Eukaryotic cells contain a nucleus that is kept separate from the cytoplasm by a double membrane layer. The cytoplasm has three major elements; the cytosol, organelles and inclusions.
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Protein biosynthesis (synthesis) is the process in which cells build proteins. The term is sometimes used to refer only to protein translation but more often it refers to a multi-step process, beginning with amino acid synthesis and transcription which are then used for translation.
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Translation is the second process of protein biosynthesis (part of the overall process of gene expression). Translation occurs in the cytoplasm where the ribosomes are located. Ribosomes are made of a small and large subunit which surrounds the mRNA.
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A membrane protein is a protein molecule that is attached to, or associated with the membrane of a cell or an organelle. More than half of all proteins interact with membranes.
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