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Chapter 6: A tour of the cell - Coggle Diagram

- - - - The third parameter, contrast, is the difference in brightness between the light and dark areas of an image. Methods for enhancing contrast include staining or labeling cell components to stand out visually.
- - - - The transmission electron microscope (TEM) is used to study the internal structure of cells. The TEM aims an electron beam through a very thin section of the specimen, much as a light microscope aims light through a sample on a slide.
- - - - In a prokaryotic cell, the DNA is concentrated in a region that is not membrane-enclosed, called the nucleoid. prokaryotic means "before nucleus" (from the Greek pro, before, reflecting the earlier evolution of prokaryotic cells.
        
        The interior of either type of cell is called the cytoplasm; in eukaryotic cells, this term refers only to the region between the nucleus and the plasma membrane., These membrane-bounded structures are absent in almost all prokaryotic cells, another distinction between prokaryotic and eukaryotic cells.
- - - - the nuclear side of the envelope is lined by the nuclear lamina, a netlike array of protein filaments (in animal cells, called intermediate filaments) that maintains the shape of the nucleus by mechanically supporting the nuclear envelope.
- - - - Ribosomes, which are complexes made of ribosomal RNAs and proteins, are the cellular components that carry out protein synthesis .(Note that ribosomes are not membrane bounded and thus are not considered organelles.)
- - - - Vacuoles are large vesicles derived from the endoplasmic reticulum and Golgi apparatus. Thus, vacuoles are an integral part of a cell's endomembrane system.
        
        Vacuoles perform a variety of functions in different kinds of cells.
        Food vacuoles, formed by phagocytosis, have already been mentioned .
        
        Vacuoles perform a variety of functions in different kinds of cells.
        Food vacuoles, formed by phagocytosis, have already been mentioned .
        
        Many unicellular protists living in fresh water have contractile vacuoles that pump excess water out of the cell, thereby maintaining a suitable concentration of ions and molecules inside the cell.
        
        Mature plant cells generally contain a large central vacuole , which develops by the coalescence of smaller vacuoles.
- - - - The second compartment, the mitochondrial matrix, is enclosed by the inner membrane.
        
        The outer membrane is smooth, but the inner membrane is convoluted, with infoldings called cristae
        
        Inside the chloroplast is another membranous system in the form of flattened, interconnected sacs called thylakoids. In some regions, thylakoids are stacked like poker chips; each stack is called a granum (plural, grana). The fluid outside the thylakoids is the stroma, which contains the chloroplast DNA and ribosomes as well as many enzymes.
        
        The peroxisome is a specialized metabolic compartment bounded by a single membrane (Eigure 6.12). Peroxisomes contain enzymes that remove hydrogen atoms from various substrates and transfer them to oxygen (O2), producing hydrogen peroxide
        (H2O2) as a by-product (from which the organelle derives its name).
        
        The chloroplast is a specialized member of a family of closely related plant organelles called plastids. One type of plastid, the amyloplast, is a colorless organelle that stores starch (amylose), particularly in roots and tubers.
- - - - There are many such examples: Cytoskeletal elements and motor proteins work together with plasma membrane molecules to allow whole cells to move along fibers outside the cell.
        
        Microtubules are the thickest of the three types; microfilaments (also called actin filaments) are the thinnest; and intermediate filaments are fibers with diameters in a middle range
- - - - The microtubule assembly of a cilium or flagellum is anchored in the cell by a basal body, which is structurally very similar to a centriole, with microtubule triplets in a "9 + O" pattern
        
        Bending involves large motor proteins called dyneins (red in the diagram in Figure 6.24) that are attached along each outer microtubule doublet.
- - - - The cell crawls along a surface by extending cellular extensions called pseudopodia (from the Greek pseudes, false, and pod, foot) and moving toward them
        
        In plant cells, actin-protein interactions contribute to cytoplasmic streaming, a circular flow of cytoplasm within cells
- - - - A young plant cell first secretes a relatively thin and flexible wall called the primary cell wall (see the micrograph in Eigure 6.27).
        Between primary walls of adjacent cells is the middle lamella, a thin layer rich in sticky polysaccharides called pectins.
        
        Other cells add a secondary cell wall between the plasma membrane and the primary wall. The secondary wall, often deposited in several laminated layers, has a strong and durable matrix that affords the cell protection and support.
        Wood, for example, consists mainly of secondary walls.
- - - - Some cells are attached to the ECM by ECM glycoproteins such as fibronectin. Fibronectin and other ECM proteins bind to cell-surface receptor proteins called integrins that are built into the plasma membrane.