The shapes of prokaryotic and eukaryotic cells are determined by their external cover (the cell walls or cell membrane).
PROKARYOTIC CELL SHAPES
The main organisms classified as prokaryotes are the bacteria. Bacteria are further divided into four groups based on their shapes:
- Spherical-shaped bacteria: These are commonly called cocci bacteria. They include diplococci, sarcina, streptococci, staphylococci and the tetrad bacteria. Cocci bacteria are usually less than 1ʮm in diameter. Diplococci are paired cocci, example are: Neisseria gonorrhoea Moraxella catarrhalis, Acinetobacter spp and Enterococcus spp. Staphylococci are clustered (grape-like cocci, examples are Staphylococcus aureus, S epidermidis and S. saprophyticus while Streptococci are cocci in chains, examples are Streptococcus pyogens, S. mitis, S.bovis and S. pneumoniae. Sarcina aiscocci arranged in a cluster of eight, an example is Sarcina maxima. Tetrad aiscocci arranged in fours, an example is Micrococcus let us
- Rod-shaped bacteria: The rod-shaped bacteria are of three types: Single rods, Chain-like rods. Examples of single-rods are Escherichia coli and Salmonella typhi, examples of chain-like rods are Azotobacter, Bacillus, and Clostridium species.
- spiral-shaped bacteria: These are helical rods with a singular flagellum. Examples are Spirillum volutans and Spirillum winogradskyi and spirochaetes such as Treponema pallidum, the causal agent of Syphilis
- Comma-shaped bacteria: They are the Vibrios usually with a single flagellum. Examples include Vibrio vulnificus and cholera.
EUKARYOTIC CELL SHAPES
Plants cells are rigid and rectangular in shape due to the possession of cell wall while animal cells are circular and flexible in shape because they do not possess ca ell wall. Fungi cells are usually irregular and circular in shape. The single cell algae can either be spherical, rod, club or spindle-shape depending on their respective species while the multicellular algae can either be branched or unbranched depending on their species. Protist shapes varying species, some are irregularly shaped (e.g Amoeba), some aree spindleshaped (e.g Euglena Viridis) and some are oval shaped (e.g Paramecium).
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