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Download Unit 1: Unity and Diversity Cells In Action
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Unit 1: Unity and Diversity Cells In Action Life manages very well without oxygen, evolving into flourishing communities of anaerobes. Acidity... presents no problem, as sulphur bacteria and their co-habitants illustrate, nor does a considerable degree of alkalinity bother alkophiles.... Water purity is a trivial matter: saturated salt brines support abundant bacterial life. And pressure is quite irrelevant, with bacteria growing happily in a near vacuum or at the huge hydrostatic pressure of deep ocean trenches. Even organic food is not a prerequisite...." Temperature, too, presents little problem: boiling hot springs support bacterial life, and bacteria have been found growing at 112 0C in superheated geothermal water under hydrostatic pressure. Conversely, other types of bacteria thrive at well below zero, provided the water is salty enough not to freeze, and even if they do get frozen, many bacteria revive when their habitat thaws. Classification • Viruses – not considered living but have some features of cells HIV • Prokaryotic – simple cells bacilli • Eukaryotic – complex cells Cells of Living Things Cells of Living things Prokaryotic cells Monera (Bacteria, Cyanobacteria) Single celled Lack distinct nucleus One circular DNA strand Lack membrane bound organelles Non-cellulose cell wall Eukaryotic cells Plantae Multicellular Membrane bound nucleus present Membrane bound organelles Chloroplasts present in photosynthetic cells Cellulose cell wall Usually large vacuoles Cell membrane Plant cells are bound together in tissues or aggregations by other molecules, such as pectin. Animalia Multicellular Membrane bound nucleus present Membrane bound organelles present No chloroplasts No cell wall Vacuoles small or absent Cell membrane Cells bound together in an extracellular matrix by a triple helix of protein known as collagen. Protista Single celled or in colonies Membrane bound nucleus present Membrane bound organelles Chloroplast present in many species but may be absent Different types of cell walls Vacuoles present Fungi Normally multicellular Membrane bound nucleus present Membrane bound organelles present No chloroplasts Non-cellulose cell wall Vacuoles present Cells are bound together in tissues or aggregations by other molecules, such as pectin. Prokaryotic Cells Eukaryotic Cells How Big? Plasma Membrane Nucleus Ribosomes Endoplasmic Reticulum Golgi Apparatus Building and transporting proteins Mitochondria Vesicles Lysosomes Cell Wall Plastids: Chloroplasts Plastids: amyloplast Cilia and Flagella
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