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Questions and Answers
Which of the following is not a basic shape of bacteria?
Which organisms are represented by prokaryotic cells?
What is a characteristic of prokaryotic cells?
Which of the following bacteria shapes correctly matches its description?
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Which of the following statements is accurate regarding prokaryotic cells?
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Which of the following structures is present in a prokaryotic cell but not in a eukaryotic cell?
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What is the correct order of the layers found in the cell envelope of a typical bacterium from outermost to innermost?
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Which one of the following is incorrect about typical prokaryotic cells?
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What is a unique characteristic conferred by plasmids in prokaryotes?
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Which of the following describes the function of the cell wall in prokaryotic cells?
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Which of the following statements is true regarding the size of prokaryotes compared to eukaryotes?
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Study Notes
Prokaryotic Cells
- Prokaryotic cells are represented by bacteria, blue-green algae, mycoplasma, and PPLO (Pleuro Pneumonia Like Organisms).
- They are generally smaller and multiply more rapidly than eukaryotic cells.
- They vary greatly in shape and size.
Shapes of Bacteria
- Bacillus: rod-like shape
- Coccus: spherical shape
- Vibrio: comma-shaped
- Spirillum: spiral shape
Prokaryote Structure
- A typical prokaryotic cell has a cell wall surrounding the cell membrane (except in mycoplasma).
- Cytoplasm fills the cell.
- There is no nucleus.
- Genetic material (DNA) is not enclosed in a membrane.
- Prokaryotes may have small circular DNA outside the genomic DNA, called plasmids.
- Plasmids confer specific characteristics to bacteria, such as antibiotic resistance.
Cell Envelope
- The cell envelope of a prokaryote is a complex, three-layered structure.
- Glycocalyx: outermost layer
- Cell wall: middle layer
- Plasma membrane: innermost layer
- Each layer has a distinct function, but they act together as a single protective unit.
Size Comparison
- Typical bacteria: 1-2 µm
- PPLO: about 0.1 µm
- Viruses: 0.02-0.2 µm
- Typical eukaryotic cell: 10-20 µm
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Description
Learn about the characteristics, shapes, and structures of prokaryotic cells, including bacteria, blue-green algae, and more.
