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All living things are made up of cells. Scientists use microscopes to view cells: light microscopes or electron microscopes. Part Composition Cell membrane No definite shape Made of phospholipid and protein Nucleus Nucleolus Surrounded by a double membrane and con- tains chromosomes (DNA and protein...

All living things are made up of cells. Scientists use microscopes to view cells: light microscopes or electron microscopes. Part Composition Cell membrane No definite shape Made of phospholipid and protein Nucleus Nucleolus Surrounded by a double membrane and con- tains chromosomes (DNA and protein) DNA, RNA and proteins Function Controls the passage of chemicals in and out of the cell (is selectively permeable) Acts as the boundary of the cell Controls all activity of the cell Manufactures RNA Nuclear membrane Double layer of plasma membrane Nuclear pore Gaps in the membrane with protein complexes Contains the nucleus Controls the passage of material in and out of the nucleus, particularly RNA Stores water, sugar and salt Vacuole Mitochondrion Ribosome Cell wall* Chloroplast* *Plant cells only Looking at cells: Membrane-bound space in cytoplasm (large in plants) Double-membraned organelle with own DNA RNA and protein Cellulose fibres Double-membraned organelle with chlorophyll and own DNA Place cell on slide with water. Cover with coverslip (to protect lens). Lower the coverslip gently (to prevent air bubbles). Stain (to make more visible): Methylene blue for animal cells. ⚫lodine solution for plant cells. Place on stage of microscope. Focus with low then high power. Aerobic respiration occurs here Manufactures protein Give shape and rigidity (with vacuole); is fully permeable Photosynthesis occurs here The total magnification is determined by multiplying the magnification of the eyepiece by the magnification of the objective lens. There are two types of cells: 1. Prokaryotic Has no membrane-bound structures within the cell Has no nucleus Example is bacteria. 2. Eukaryotic Has membrane-bound structures within the cell Has a nucleus All organisms with the exception of bacteria are eukaryotes.