Chapter 6 Tour of the Cell
Notes
Terms : Hide Images [1]
| *the simplest collection of matter that can live *structure is correlated to cellular functions *All Cells are related by thier descent from earlier cells *Though usually too small to be seen by the naked eye, cells are very complex | ||
| *light passes through the specimen and through glass lenses, which magnify images *Can magnify effectively to about 1,000 times the size of the actual specimen, at higher magnifications, the image blurs *can resolve individual cells, but cannot resolve much of the internal anatomy, especially the organelles | ||
| Depends on: Magnification-the ratio of an objects image size to its real size Resolution-The measure of the clarity of the image, The minimum distance 2 points can be seperated by and still be viewed as 2 seperate points contrast-visible differences in parts of the sample | ||
| SEM (scanning Electron microscope) TEM (transmission electron microscope) | ||
| *focus a beam of electrons onto the surgace of a specimen, providing images that look 3D *useful in studying surface structures *has great depth of field, resulting in an image that seems 3 Dimensional | ||
| *focus a beam of electrons through the specimen *Used mainly to study the internal structure of cells *aims an electron beam through a thin section of the specimen *the image is focused and magnified by electromagnents *enhances contrast, the thin sections are stained with atoms of heavy metals | ||
| *Takes cells apart and seperates the major organelle from one another *enables scientists to determine the functions of organelles | ||
| fractionate cells into their component parts | ||
| all parts of the cell mix together seperates 1. nuclues 2. mitochondria 3. membrane ER/Golgi 4. ribosomes | ||
| *Protists, fungi, and animals have eukaryotic cells *Dna in a nuclues that is bounded by a membranous nuclear envelope *membrane bound organelles *cytoplasm is the region between the plasma membrane and nucleus *GENERALLY much larger than prokaryotic cells *have internal membranes that partition the cell into organelles *genetic info is stored in the nucleus and carried out by the ribosomes | ||
| *Plasma Membrane, semifluid substance called cytosol, chromosomes to carry genes, ribosomes to make proteins | ||
| *No nucleus *Dna in an unbound region called the nucleotoid *no membrane bound organneles *cytoplasm bound by the plasma membrane | ||
| *functions as a selective barrier that allows passage of oxygen, nutrients, and wastes for the whole volume of the cell *Made of Phosopholipids and proteins | ||
| *the logistics of carrying out metabolism set limits on cell size *most bacteria are 1-10 microns in diameter *eukaryotic cells are typically 10-1000 microns in diameter *Larger organisms do not generally have larger cells than smaller organisms, just more cells *Metabolic requirements also set an upper limit to the size of a single cell | ||
| *the volume of cytoplasm determines the need for this exchange of nutreints and wastes *rates of chemical exchange may be inadequate to maintain a cell with a very large cytoplasm * as a cell increases in size, its colume increases faster than its surgace area *smaller organisms have a greater ration of surface area to volume | ||
| *contains most of the DNA in a eukaryotic cell, though some DNA is stored in mitochondria and chloroplasts |