Understanding the composition of cells and how cells works 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.
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 comparments 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 constant flux of proteins through these compartments. ER and Golgi-resident proteins associate with other proteins and remain in their respective compartments. Other proteins "flow" through the ER and Golgi to the plasma membrane. From the plasma membrane, proteins destined to be degraded move back into intracellular compartments where they are broken down to their individual amino acids.
Techniques
Purification of cells and their parts
Purification of cells and their parts is achieved in the following ways:
This article contains material from theScience Primer (http://www.ncbi.nlm.nih.gov/About/Primer)published by the NCBI, which, as a US government publication, is in the public domain[1] (http://www.ncbi.nlm.nih.gov/About/disclaimer.html).
Today biology is subdivided into hierarchies based on the molecule, the cell, the organism, and the population.
Organismal biology, in turn, is related to cellularbiology, because the life functions of multicellular organisms are governed by the activities and interactions of their cellular components.
Human populations are by convention not considered within the province of biology; instead, they are the subject of anthropology and the various social sciences.
The primary divisions of study in biology consist of zoology (animals), botany (plants), and protistology (one-celled organisms), and are aimed at examining such topics as origins, structure, function, reproduction, growth and development, behavior, and evolution of the different organisms.
Alternatively, biology can be divided into fields especially concerned with one type of living thing; for example, botany (plants), zoology (animals), ornithology (birds), entomology (insects), mycology (fungi), microbiology (microorganisms), and bacteriology (bacteria).
The methods and attitudes of other sciences are brought to the study of biology in such fields as biochemistry (physiological chemistry), biophysics (the physics of life processes), bioclimatology and biogeography (ecology), bioengineering (the design of artificial organs), biometry or biostatistics, bioenergetics, and biomathematics.
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