Cells
Animal Cells
Nucleus - Genetic Material
Cytoplasm - where most chemical reactions happen, enzymes to control these.
Cell membrance - holds cell together, controls what goes in and out
Mitochondria - most reactions for aerobic respiration
Ribosomes - proteins are synthesized
Plant cells
Cell wall - rigid structure, cellulose, supports and strengthens cell e.g. algae
Permanent vacuole - stores cell sap
Chloroplasts - contain chlorophyll (which absorbs light for photosynthesis), where photosynthesis occurs
Bacterial cells
Cytoplasm and cell membrance, surrounded by a cell wall
Single circular strand of DNA
Can have plasmids (small rings of DNA)
Microscopy
Light microscopes
Use light and lenses to magnify an image
Let us see cells and large subcellular structures e.g. nuclei
Electron Microscopes
Electrons to form an image
Migher magnification
Higher resolution (ability to distinguish between two points)
Let us see smaller things in more detail e.g. internal structure of mitochondria
Preparing a slide for a light microscope
1)Add a drop of water to the middle of a clean slide
2)Peel off some epidermal tissue from a layer of onion
3)Place the epidermal tissue on the slide (in the water)
4)Add a drop of iodine, stains are used to highlight objects by giving colour to them.
Observing the specimen
5)Place a cover slip on top
1)Clip the slide onto the stage and select the lowest-powered objective lens
2)Use the coarse adjustment know to move the stage to just below the lens
3)Use the coarse adjustment knob to move the stage downwards until the image is roughly in focus
4)Use the fine adjustment knob to adjust the focus until you get a clear image of what's on the slide.
5)If you need a greater magnification swap to a higher-powered objective lens and refocus
Cell Differentiation and Specialisation