All living things are made up of cells. Some organisms, like yeast, are only single-celled, while others, like humans, contain many cells. Cells are bounded by a plasma membrane which is so thin it is often invisible even with a light microscope. Cells of organisms such as plants have a cell wall outside the plasma membrane. The most important organelle (-elle = small) within eukaryotic cells is the nucleus. Remember that, unlike yeast, humans, and other such eukaryotes (eu- = good, well, true), bacteria, which are prokaryotes, (pro = before, in front of; karyon = nut, kernel, nucleus) do not have their DNA organized into a nucleus. When a cell is “stained,” the nucleus often takes dye well, especially in the region(s) of the nucleolus (pl. = nucleoli). The region between the nucleus and the plasma membrane is called the cytoplasm (cyto = cell), which contains a number of other kinds of organelles. Some of these are visible only with an electron microscope and/or special staining techniques, while others are easily visible with a light microscope. Various vacuoles (vacu = empty) are usually visible. Many plant cells have a large central vacuole which often takes up more space than the cytoplasm. In plants, chloroplasts (chloro = green; plasti = formed, molded) are easily seen, as well as various other plastids including leucoplasts (leuco = white) and chromoplasts (chromo = color). If present, cilia (cilium = eyelid, eyelash, small hair) and flagella (flagellum = a whip) can sometimes be seen by their shadow (or with a special stain), although not in great detail. There are special stains available to enable us to see.
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ReplyDeleteAll living things are made up of cells. Some organisms, like yeast, are only single-celled, while others, like humans, contain many cells. Cells are bounded by a plasma membrane which is so thin it is often invisible even with a light microscope. Cells of organisms such as plants have a cell wall outside the plasma membrane. The most important organelle (-elle = small) within eukaryotic cells is the nucleus. Remember that, unlike yeast, humans, and other such eukaryotes (eu- = good, well, true), bacteria, which are prokaryotes, (pro = before, in front of; karyon = nut, kernel, nucleus) do not have their DNA organized into a nucleus. When a cell is “stained,” the nucleus often takes dye well, especially in the region(s) of the nucleolus (pl. = nucleoli). The region between the nucleus and the plasma membrane is called the cytoplasm (cyto = cell), which contains a number of other kinds of organelles. Some of these are visible only with an electron microscope and/or special staining techniques, while others are easily visible with a light microscope. Various vacuoles (vacu = empty) are usually visible. Many plant cells have a large central vacuole which often takes up more space than the cytoplasm. In plants, chloroplasts (chloro = green; plasti = formed, molded) are easily seen, as well as various other plastids including leucoplasts (leuco = white) and chromoplasts (chromo = color). If present, cilia (cilium = eyelid, eyelash, small hair) and flagella (flagellum = a whip) can sometimes be seen by their shadow (or with a special stain), although not in great detail. There are special stains available to enable us to see.
ReplyDeleteIn other words Different type of cells when put in same type groups will turn certain colors because of reaction.
DeleteI think there are just so many it makes it visible, like polar bear fur.
ReplyDelete