cell nomenclature
Terms
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- nuclear envelope
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nuclear envelope
regulates passage of substances between the cytoplasm and nucleus - centrioles
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Centrioles
during mitosis, forms the spindle and asters; forms bases of cilia & flagella - cilia
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cilia
move in union, creating a water current which moves substances across the cellsurface - nucleus
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nucleus
control center for cell - intermediate filaments
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intermediate filaments
stable cytoskeletal elements which resist mechanical forces - rough ER
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rough ER
makes (processes) all proteins secreted from the cell; it also makes (processes) proteins and phospholipids destined for the plasma membrane - smooth ER
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smooth ER
site of lipid and steroid synthesis; lipid metabolism; drug detoxification - nucleoli
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nucleoli
site of ribosome subunit manufacture
In the nucleus is a region of densely stained fibers and granules adjoining chromatin, the nucleolus.
In the nucleolus, ribosomal RNA (rRNA) is synthesized and assembled with proteins from the cytoplasm to form ribosomal subunits.
The subunits pass from the nuclear pores to the cytoplasm where they combine to form ribosomes. - Ribosomes
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Ribosomes Ribosomes build a cellÂ’s proteins
Ribosomes contain rRNA and protein.
A ribosome is composed of two subunits that combine to carry out protein synthesis.
Cell types that synthesize large quantities of proteins (e.g., pancreas) have large numbers of ribosomes and prominent nuclei.
Some ribosomes, free ribosomes, are suspended in the cytosol and synthesize proteins that function within the cytosol.
Other ribosomes, bound ribosomes, are attached to the outside of the endoplasmic reticulum.
These synthesize proteins that are either included into membranes or for export from the cell.
Ribosomes can shift between roles depending on the polypeptides they are synthesizing. - ER
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Endoplasmic Reticulum
The endoplasmic reticulum manufactures membranes and performs many other biosynthetic functions
The endoplasmic reticulum (ER) accounts for half the membranes in a eukaryotic cell.
The ER includes membranous tubules and internal, fluid-filled spaces, the cisternae. - Lysosomes
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Lysosomes are digestive compartments
· The lysosome is a membrane-bounded sac of hydrolytic enzymes that digests macromolecules.
· Lysosomal enzymes can hydrolyze proteins, fats, polysaccharides, and nucleic acids.
· These enzymes work best at pH 5. - Vacouoles
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Vacuoles have diverse functions in cell maintenance
· Vesicles and vacuoles (larger versions) are membrane-bound sacs with varied functions.
· Food vacuoles, from phagocytosis, fuse with lysosomes.
· Contractile vacuoles, found in freshwater protists, pump excess water out of the cell.
· Central vacuoles are found in many mature plant cells - mitochondria
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mitochondria
site of ATP production; often called the powerhouse of the cell. Mitochondria and chloroplasts are the organelles that convert energy to forms that cells can use for work.
Mitochondria are the sites of cellular respiration, generating ATP from the catabolism of sugars, fats, and other fuels in the presence of oxygen - Peroxisomes
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Peroxisomes generate and degrade H2O2 in performing various metabolic functions
Peroxisomes contain enzymes that transfer hydrogen from various substrates to oxygen
An intermediate product of this process is hydrogen peroxide (H2O2), a poison, but the peroxisome has another enzyme that converts H2O2 to water.
Some peroxisomes break fatty acids down to smaller molecules that are transported to mitochondria for fuel. - cytoskeleton
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Providing structural support to the cell, the cytoskeleton also functions in cell motility and regulation
The cytoskeleton provides mechanical support and maintains shape of the cell.
The fibers act like a geodesic dome to stabilize a balance between opposing forces.
The cytoskeleton provides anchorage for many organelles and cytosolic enzymes. - flagella
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flagella
propel cells. The cilium or flagellum is anchored in the cell by a basal body, whose structure is identical to a centriole. - Golgi apparatus
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Golgi apparatus
modifies and then packages substances into vesicles for transport to their final destination (either elsewhere in the cell or to the plasmamembrane.The Golgi apparatus finishes, sorts, and ships cell products
Many transport vesicles from the ER travel to the Golgi apparatus for modification of their contents.
The Golgi is a center of manufacturing, warehousing, sorting, and shipping. - microtub
- Microtubles function freely in the formation and dissemble of cellular organelless, sometimes even serving as rails for carrying small membrane vesicles. For switching over among the various roles, control of the formation and assembly is indispensable.
- chromatin
- Chromatin is that portion of the cell nucleus which contains all of the DNA of the nucleus in animal or plant cells. (A small amount of special DNA is also found in the mitochondria of the cell cytoplasm outside of the cell nucleus.)