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Cells and Microscopy I - Coggle Diagram
Cells and Microscopy I
Cell structure
Eukaryotes are organisms that are made up of eukaryotic cells and are multicellular e.g. animal and plants cells
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Nucleus - contains the genetic material that controls the activities of the cell. Genetic material is arranged in chromosomes.
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Mitochondria - where most reactions for aerobic respiration take place. Transfers energy and helps cells to work
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Plant cell
Cell wall - rigid structure made of cellulose, supports and strengthens the cell
Large vacuole - contains sell sap, solution of sugar and salts, which maintains the internal pressure to support the cell.
Chloroplasts - Where photosynthesis occurs which makes food for the plant and contains chloropyhll which absorbs light needed for photosynthesis
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Specialised cells
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egg
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after fertilisation it changes shape to prevent other sperm from getting in so embryo has correct number of Dna
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Microscopes
light
Use light and lenses to form an image and magnify it. They let us see individual cells and subcellular structures like nuclei and chloroplasts.
electron
Use electrons to form an image. They have a higher magnification and resolution which gives a sharper clearer image.
Let us see smaller things in detail which gives a better understanding of how cells work and the role of subcellular structures in cells but cannot be used to view living things.
Preparing a slide
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2) Cut up an onion and separate it out into layers. Use tweezers to peel of some epidermal tissue from the bottom of some of the layers
3) Using the tweezers, place the epidermal tissue into the water on the slide
4) Add one drop of iodine solution. Iodine solution is a stain. Stains are used to add colour into objects in a cell, making them easier to see. e.g. methylene blue used to stain DNA
5) Place a cover slip on the slide next to the water droplet, then holding it at an angle with a mounted needle, carefully lower it so it covers the specimen. Try not to get air bubbles under as they will obstruct the view.
Observing a Specimen
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4) Look down the eyepiece. Use the coarse adjustment knob to move the stage downwards until the image is in focus.
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6) If you need to see the slide with greater magnification, swap to a higher powered objective lens and refocus
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