Microorganisms- Mas'ood Adam Flashcards
What are disease causing microorganisms called?
Pathogens
Describe the basic structure of a virus
Very small (20nm-450nm)
Consist of nucleic acid surrounded by a protein capsule
Contain DNA or RNA
Describe the general characteristics of viruses
They are acellular
Known as obligate intracellular parasites
Are host specific (some are tissue-specific)
Are pathogenic
Convert genetic material (DNA or RNA) into viral nucleic acids for reproduction
Basic structure of bacteria
Unicellular Prokaryotic Bacterium cell surrounded by a cell wall Cell wall is surrounded by a slime layer or capsule Plasma membrane encloses the cytoplasm DNA found in the nucleoid
Shapes of bacteria
Rod-shaped (bacillus)
Spherical/round (coccus)
Spiral-shaped (spirillum)
Comma-shaped (vibrio)
Describe the general characteristics of bacteria
Unicellular
Prokaryotic
Some are autotrophic while a majority of bacteria is heterotrophic
Reproduction occurs asexually by binary fission
Describe the basic structure of protists
Uni- or multicellular
Algae contains chloroplasts
Protozoa ingest food by phagocytosis
Describe the general characteristics of protists
Eukaryotic
Algae are autotrophic
Reproduction mostly asexual by binary fission. However, some algae reproduce sexually
Most protists are aquatic
Describe the basic structure of fungi
Some are macroscopic (mushrooms) and others microscopic (yeasts)
Cell walls made of chitin
Yeasts are unicellular and reproduce asexually by budding
Multicellular fungi consists of branched mass of filaments called hyphae which together form the mycelium
Describe the role of microorganisms as producers
Autotrophic bacteria and protists (algae) produce their own organic nutrients
These organisms form the first link (producers)
Energy is stored in carbohydrates and is available to the next tropic level
Describe the role of microorganisms as decomposers
Decomposition bacteria, saprophytic fungi and protists break down dead organic matter
water, carbon dioxide, ammonia and heat energy are released during decomposition
Elements are recycled in the environment and are available for uptake by plants
Describe the role of microorganisms in the nitrogen cycle
Free-living soil bacteria and nodule bacteria convert free nitrogen into nitrates
The ammonia that is released is processed by the nitrifying bacteria into nitrates and nitrites
Ammonia and nitrates are converted into free nitrogen in the atmosphere by denitrifying bacteria
