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* History of the cell: The development and refinement of magnifying lenses and light microscopes made the observation and description of microscopic organisms and living cells possible. * *Leeuwenhoek – developed and improved simple microscopes; he saw small living things in a drop of pond water and called them “animalcules”. * *He studied cork with a microscope and described the small boxes he decided to call cells after rooms in monasteries. *He named the cell a “cell”. * *A German botanist who concluded that all plants are made of cells. * *A German zoologist who concluded that all animals are made of cells. * * * All living things are made of cells. * The cell is the basic unit of structure and function in all living things. * All cells come from pre-existing cells. * MODERN CELL THEORY ADDS: * Energy flow occurs within cells. * Cells contain hereditary information that is passed from cell to cell during cell division. * All cells are basically the same in chemical composition in organisms of similar species. * Continued advancements in microscopy allowed the observation of cell organelles and internal structure. * * Two types were developed in the mid 1900’s. * The scanning electron microscope (SEM) uses a beam of electrons to scan the surface of a cell. * * * Prokaryotes are cells that do not contain a nucleus or other membrane-bound organelles. * They are much smaller that eukaryotes. * Bacteria are prokaryotes. * * *Organelles are membrane-bound structures in a eukaryotic cell. *Each organelle has a specific function for cell survival. * • All cells, prokaryotic and eukaryotic, have a plasma membrane. • It is a phospholipid bilayer. • It is selectively permeable as it regulates what goes in and out of the cell. * *The nucleus controls all cellular functions. *It contains chromatin which is made up of DNA and proteins. *DNA is the blueprint for all cellular activity. • The nucleolus is found in the nucleus. • It produces ribosomes. • It is the dark, dense regions of the nucleus. * * Ribosomes are where proteins are made. * Some are free in the cytoplasm and some are bound to the endoplasmic reticulum. * Ribosomes are NOT membrane-bound and are found in both eukaryotes and prokaryotes. * * The cytoplasm is all cellular contents outside the nucleus in eukaryotic cells. * * The ER is a series of membranous canals for the transport of materials. * They are the sites of chemical reactions. * Rough ER – ribosomes are attached that are producing proteins * Smooth ER – no ribosomes attached; involved in production and storage of lipids * * *Also called the Golgi bodies or Golgi complex *It receives proteins from the ER. *It modifies, packages, and ships the proteins. * *Vacuoles are membrane-bound sacs for temporary storage. * *They are the cell’s recyclers. *Lysosomes contain digestive enzymes to digest worn out organelles, food particles, or viruses. * * *These are the sites for photosynthesis. *They capture light energy and convert it to chemical energy. *The chemical energy is stored in food molecules. * These are the sites for cellular respiration. * They are called the “powerhouse of the cell”. * They break down food molecules and release energy. * *This support structure in the cytoplasm is composed of microtubules and microfilaments. * *Centrioles are involved in cell division. They are found only in animal cells. * *These are short, numerous hair-like projections on the cell surface for locomotion or feeding. * *Flagella are longer projections on the cell surface that move with a whip-like motion. *They are primarily used for locomotion. * * *The cell wall is an inflexible barrier that protects the cell and gives it support. *They are found in prokaryotes, fungi, plants, and in plant-like protists. *Plant cells have a cell wall as well as a plasma membrane. *Animal cells only have a plasma membrane. * *Plant cells have chloroplasts and mitochondria. *Animal cells only have mitochondria. * *Plant cells have a large central vacuole for water storage. *Animal cells only have small, temporary vacuoles. * *Animal cells have centrioles. cells do not. Plant