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Transcript
What are Cells? Cells are the building blocks of all living things. A cell is the smallest unit of living matter. Prokaryotic Cells Bacteria are prokaryotes. Their cells are very small and very simple. Eukaryotic cells All other cells are eukaryotic cells. These include protists, fungi, plants, and animals. The diagram below shows link between bacteria, archaea, and the four other kingdoms. Cells contain parts called organelles. These all have a specific structure and have a special function (job). Cell membrane All cells are surrounded by a membrane. Function: It separates the inside of the cell from its environment and controls what goes in and out of the cell. Look at the amoeba below: Nucleus The nuclei can be seen in the photograph of human cheek cells below. Function: Contains the DNA which has all the instructions needed to make the cell work. Cytoplasm This is the material enclosed by the cell membrane, not including the nucleus. Function: where the chemical reactions happen Cell membrane cytoplasm nucleus Cell Wall Function: to support and protect the cell. The cell walls of these onion skin cells can be easily seen. Some other cell parts…. Vacuoles Vacuoles are little sacs that store water and dissolved substances (sap). They are more important in plant cells. Most of the center of a plant cell is occupied by a central vacuole. The central vacuole gives support because pressure within the vacuole makes the cell rigid (turgid). The cell wall prevents the cell from bursting. Chloroplasts Plants make their food by photosynthesis. This uses light to make sugar from CO2 and H2O. Only certain cells contain chloroplasts, where photosynthesis occurs. The photograph below is an Elodea leaf (X 400). The many green structures are chloroplasts. Ribosomes Ribosomes are found in many places around the cell. You might find them floating in the cytoplasm. Function: Cells need to make proteins. Ribosomes are the protein builders of the cell. Mitochondria These are known as the powerhouses of the cell and create energy for the cell. The process of creating cell energy is known as cellular respiration.