Cells Cell Theory Cells are the basic units
Cells
Cell Theory Cells are the basic units of living organisms. n The cell theory states that: n ¨ All living things are made of one or more cells. ¨ Cells are the basic unit of structure and function in living things. ¨ All cells come from other cells.
Sizes of Living Things Copyright © The Mc. Graw-Hill Companies, Inc. Permission required for reproduction or display. 0. 1 nm 100 nm protein amino acid 1 m chloroplast 10 m 100 plant and animal cells m 1 mm 1 cm human egg atom ant 1 m 100 m 1 km rose mouse frog egg virus most bacteria 0. 1 m ostrich egg blue whale human electron microscope light microscope human eye 3
Characteristics of All Cells A surrounding membrane n Cytoplasm – cell contents in thick fluid n Organelles – structures for cell function n Control center with DNA n
Classification of Life Prokaryotic Eukaryotic
Cell Types n Two categories: 1. Prokaryotic cells - Unicellular organisms such as bacteria are examples of prokaryotes. 2. Eukaryotic Cells - All other cells are these.
Prokaryotic Cells n Lack a membrane-bound nucleus n Structurally smaller and simpler than eukaryotic cells (which have a nucleus). n Most ancient and abundant type of cells n Prokaryotic cells are placed in two taxonomic domains: ¨ Bacteria ¨ Archaea n Live in extreme habitats 7
The Structure of Bacteria n n Extremely small - 1– 1. 5 μm wide and 2– 6 μm long Occur in three basic shapes: Spherical coccus, ¨ Rod-shaped bacillus, ¨ Spiral spirillum (if rigid) or spirochete (if flexible). ¨ spirillum spirochete bacillus coccus 8
Prokaryotic Cell Structure n Have a simple cell structure
Prokaryote Cells Parts n capsule: slimy outer coating n cell wall: tougher middle layer n cell membrane: delicate inner skin
Prokaryote cells are simply built cytoplasm: inner liquid filling n DNA in one big loop n flagella: for swimming n ribosomes: for building proteins n
Video Recap n Bacteria
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