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# Bacteria - Bacteria are unicellular organisms. Because they have no nucleus, the cells are describes as prokaryotic. - The three major basic shapes of bacteria are bacillus, coccus, and spiral. It also vary in size. - Most bacteria have a peptidoglycan cell wall; they divide by binary fission; and...

# Bacteria - Bacteria are unicellular organisms. Because they have no nucleus, the cells are describes as prokaryotic. - The three major basic shapes of bacteria are bacillus, coccus, and spiral. It also vary in size. - Most bacteria have a peptidoglycan cell wall; they divide by binary fission; and they may possess flagella - Bacteria can use a wide range of chemical substances for their nutrition ## The Size of Bacteria - Bacteria are generally smaller than the cells of eukaryotes, but larger than viruses. Bacteria are measured in units of length called micrometers, or microns. - Most bacteria range from 1 to 5 microns in size. The light microscope can magnify an image approximately 1,000 times, and is used for basic studies of bacteria. ## Shape and Arrangement of bacteria ### 1-Cocci - Diplococci e.g.: Streptococcus pneumonia - Chain (Cocci) e.g.: Streptococcus pyogenes - Cluster or Grape like shape e.g.: Staphylococcus aureus ### 2-Bacilli - Short Bacilli e.g.: Bacillus subtilis. - Long Bacilli e.g.: Lactobacillus. spp. - Coccobacilli e.g.: Escherichia coli, Salmonella. ### 3-Spirals - comma shape: e.g.: Vibrio cholera. - Spiral shape: e.g.: Helicobacter pylori - Spirochaetes