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Questions and Answers
What is the main characteristic that distinguishes bacteria as prokaryotic organisms?
What is the main characteristic that distinguishes bacteria as prokaryotic organisms?
- Presence of a true nucleus
- Cell walls composed of peptidoglycan
- Metabolic capabilities for photosynthesis
- Genetic material (DNA) not housed within a true nucleus (correct)
Which of the following is NOT a common bacterial shape described in the text?
Which of the following is NOT a common bacterial shape described in the text?
- Rod-shaped (bacillus)
- Spherical (coccus)
- Curved (spirillum)
- Triangular (trichillus) (correct)
What substance is commonly found in archaeal cell walls instead of peptidoglycan?
What substance is commonly found in archaeal cell walls instead of peptidoglycan?
- Cellulose
- Peptidase
- Chitin
- Pseudopeptidoglycan (correct)
In what environments can archaea be found according to the text?
In what environments can archaea be found according to the text?
What type of bacteria use energy derived from sunlight and fix carbon dioxide for growth?
What type of bacteria use energy derived from sunlight and fix carbon dioxide for growth?
Most bacteria are harmless or helpful, but some are ______, causing disease in humans and other animals.
Most bacteria are harmless or helpful, but some are ______, causing disease in humans and other animals.
Figure 1.13 shows examples of common bacterial shapes. Note how coccobacillus is a combination of spherical (coccus) and rod-shaped ______.
Figure 1.13 shows examples of common bacterial shapes. Note how coccobacillus is a combination of spherical (coccus) and rod-shaped ______.
Archaea and bacteria have the same evolutionary histories.
Archaea and bacteria have the same evolutionary histories.
All archaea are human pathogens.
All archaea are human pathogens.
Photosynthetic bacteria use energy derived from organic compounds in their environment.
Photosynthetic bacteria use energy derived from organic compounds in their environment.
Bacteria are eukaryotic because their genetic material is housed within a true nucleus.
Bacteria are eukaryotic because their genetic material is housed within a true nucleus.
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Study Notes
Microorganism Characteristics
- Most microorganisms are unicellular and require artificial magnification to be seen
- Some unicellular microbes are visible to the naked eye, while some multicellular organisms are microscopic
- An object must measure approximately 100 micrometers (µm) to be visible without a microscope
Size Comparison
- A typical animal cell measures roughly 10 µm across, but is still microscopic
- Bacterial cells are typically about 1 µm
- Viruses can be 10 times smaller than bacteria
Microorganism Diversity
- Microorganisms differ from each other in size, structure, habitat, metabolism, and many other characteristics
- There are both unicellular and multicellular microorganisms
- Some microorganisms, such as viruses, are even acellular (not composed of cells)
Domains of Life
- Microorganisms are found in each of the three domains of life: Archaea, Bacteria, and Eukarya
- Microbes within the domains Bacteria and Archaea are all prokaryotes (their cells lack a nucleus)
- Microbes in the domain Eukarya are eukaryotes (their cells have a nucleus)
- Some microorganisms, such as viruses, do not fall within any of the three domains of life
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