1.2.1. Common structures in eukaryotic cells

Description Function Where
Cell wall Outermost layer of a plant cell composed of cellulose and other complex carbohydrates. Helps to support and protect the cell. P
Flagella (flagellum) Long and scarce threadlike structures that extend from the surface of the cell. Used for movement of the cell or to move fluids over the cell’s surface for absorption. A
Cilia (cilium) Short and abundant threadlike structures that extend from the surface of the cell. Used for movement of the cell or to move fluids over the cell’s surface for absorption. A
Cell membrane Outer layer composed of lipids and proteins. Controls the permeability of the cell to water and dissolved substances. A, P
Cytoplasm Viscous fluid mixture that occupies most of the cell’s interior. Wraps the nucleus and contains biomolecules, organelles and a protein fiber network (the cytoskeleton). Medium in which organelles and other internal structures exist in. The fiber network makes the cytoskeleton, which supports the shape of the cell and anchor organelles to fixed positions. A, P
Mitochondria
(mitochondrion)
Elongated organelles enclosed in a double membrane, the inner one with folds called cristae. Sites of cellular respiration, which converts sugars and fats into energy through oxidation. A, P
Chloroplasts Elongated organelles enclosed in a double membrane and with vesicles containing chlorophyll. Sites of photosynthesis. P
Ribosomes Tiny organelles composed of proteins and RNA, not enclosed in a membrane. Some are free in the cytoplasm, some are attached to endoplasmic reticulum. They are the only organelles present in all cells, including prokaryotics. Sites of protein synthesis. A, P
Endoplasmic reticulum Extensive system of internal membranes. May be smooth or rough: the latter has ribosomes attached to its membrane. Site of synthesis, modification and transport of various organic biomolecules. A, P
Golgi apparatus Flattened stacks of membranes. Used in the collection, packaging, and distribution of synthesized molecules. A, P
Secretory vesicles Membrane enclosed sacks created at the Golgi apparatus. These structures contain cell secretions, like hormones and neurotransmitters. The secretory vesicles are transported to the cell surface where they release those substances outside the cell (exocytosis). A, P
Vacuoles Elongated organelles enclosed in a membrane. Few and large in plant cells. Used to store sap (water and sugars) or waste products. A, P
Lysosomes Spherical organelles enclosed in a membrane. Contain digestive enzymes for breaking down old cellular components or ingested food (smaller cells, big macromolecules). A, P
Centrosome A pair of hollow tubes (the centrioles) surrounded by protein fibers in a star-like arrangement. Plant cells have an equivalent structure. Move and organise chromosomes during mitosis and meiosis. A
Nucleus Double membrane structure that encases chromatine. Controls the cellular activity. A, P
Chromatine Long strands of DNA and protein. During cell division it is packaged into chromosomes. The DNA stores hereditary information in small units of information called genes, and expresses it. A, P
Nucleolus Highly condensed chromatine loops. Area were ribosomes are manufactured. A, P

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ACTIVITY

Make a schematic drawing reproducing the structure of a eukaryotic cell. Paint each organelle with a different color and name. Try putting in a short, or an attached table, the function of each. CLUE

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