Microorganisms, Viruses, and Kingdoms: A Biology Overview
MICROORGANISMS
Microorganisms belong to the Monera, Protist, and Fungi kingdoms. Examples include *Escherichia coli*, *Amoeba*, and *Amanita*.
They are harmful or beneficial to humans.
Beneficial microorganisms:
- Some perform photosynthesis, providing food for other living things and releasing O2.
- Some decompose organic matter.
- Some provide us with antibiotics (which destroy harmful microorganisms such as bacteria).
- Some help plants obtain certain nutrients (bacteria as well).
- Others are used in the creation of certain foods: bread, yogurt, and wine (yeasts).
Harmful microorganisms:
Pathogens cause illnesses in humans and other living things. Examples include salmonellosis and meningitis.
VIRUSES
*Viruses do not belong to any kingdom because they are not alive; they cannot perform the three vital functions.
*Viruses are microscopic agents that are smaller than cells (eukaryotic/prokaryotic).
*Viruses have a simple structure:
-External protein layer (capsid)
-Nucleic acid (RNA or DNA)
Viruses can only perform the vital function of reproduction, but even for this, they need the help of a cell. They are forced to be intracellular parasites; for this reason, they are not considered living things (they are not included in any of the kingdoms). They don’t eat, and they don’t interact.
MONERA KINGDOM
Organization:
-Unicellular
-Cell wall (outer wall membrane) with three layers
-Shapes: spherical, rod-shaped, spiral, and comma-shaped
-Colonies (group together):
Cocci and bacilli group together without forming colonies:
- Diplococci (two cocci)
- Streptococci (in a row)
- Staphylococci (in clusters)
Nutrition:
1. Autotrophic: Cyanobacteria perform photosynthesis.
2. Heterotrophic: are classified by:
2.1 Parasitic: *Cholera* bacteria use organic matter produced by other living things, causing harm while doing this.
2.2 Symbiotic (= probiotics) (= bacterial flora: *Bifidus*, *Lactobacilli*, yogurts): Bacteria that live in our intestine. They live together with another living thing, and they both benefit, helping with digestion.
2.3 Saprophytic: Feed on decaying organic matter (e.g., the bacteria that appear when we die).
Reproduction:
1. Sexual processes -> conjugation: Two bacteria exchange fragments of nucleic acid through the pili, producing new variations in genetic material, leading to diversity. They can adapt to every condition:
Resistance to antibiotics (=superbacteria) – adaptation to extreme environments.
2. Asexual -> bipartition: Bacteria reproduce themselves by using bipartition – multiplication of genetic material – division of the cell into two cells.
Biological importance of bacteria:
-Ecological: They intervene in the process of recycling matter by transforming organic material into new nutrients.
-Health: Biotechnological -> essential for human beings.
-Creating medicines.
-Obtaining food products.
-Biological research.
Environments: (=resistant)
-Live in different conditions, even extremely hostile ones.
-They can divide quickly, which enables them to adapt fast to any environment.
Endospore:
When the environment becomes too hostile, they can create a protective structure.
PROTIST KINGDOM
1. Eukaryotic microorganisms (not classified in any other kingdom)
2. All aquatic or live in humid conditions.
3. Many have cilia, flagella, or pseudopodia (move).
4. Reproduction: sexual/asexual
5. Includes very different types of living things.
6. The most important ones: -PROTOZOA/ALGAE
5.1 PROTOZOA
-Unicellular, heterotrophic, made up of eukaryotic animal cells.
-First animals (10-50 um)
*Four groups (according to their ability to move or structure)
–> Free-living protozoa =
-Can live in aquatic environments or very humid terrestrial environments.
–> Parasitic protozoa:
-Cause serious illnesses in humans.
-Some of them are able to form cysts (that allow them to survive for long periods of time).
*Plasmodium: is a parasitic protozoan that transmits malaria through the sting of the *Anopheles* mosquito.
5.2 ALGAE
Organisms:
-Eukaryotic
-Photosynthetic
-Unicellular/multicellular
-Aquatic
1. Unicellular algae: live by floating in water and forming phytoplankton => this is a source of food for heterotrophic aquatic organisms. They are the main providers of oxygen in aquatic ecosystems. 1.2 Other algae live fixed to the bottom of a body of water => benthic algae.