Microorganisms: Viruses and Bacteria

Study Notes

Microorganisms

Microorganisms are too small to see with the naked eye.
Examples include: viruses, bacteria, protists, and fungi.

Viruses

Very small and not made up of cells (acellular).
Contain a central nucleic acid (DNA or RNA) surrounded by a protein capsule.
Do not perform metabolic reactions and are parasitic.
Replicate inside cells of other living organisms.
Shapes vary including rod-shaped, spherical, or complex structures.
Cause diseases in plants and animals.

Bacteria

Small, unicellular organisms classified under the kingdom Monera.
Prokaryotic (lack membrane-bound organelles like a nucleus).
Have a cell wall, plasma membrane surrounding cytoplasm.
Some have a slime layer or capsule exterior to their cell wall.
Genetic material (DNA) concentrated in a chromatin body (nucleoid).
Some move using flagella.
Reproduce asexually through binary fission.
Shapes include rod-shaped (bacillus), spherical (coccus), spiral-shaped (spirillum), and comma-shaped (vibrio).
Some are autotrophic, but most are heterotrophic.

Protists

Either unicellular or multicellular.
Eukaryotic (possess a true nucleus).
Some are autotrophic and carry out photosynthesis due to chloroplasts (like algae).
Others are heterotrophic, relying on other organisms for food (like Amoeba).
Locomotion structures include pseudopodia (Amoeba), cilia (Paramecium), and flagella (Euglena).
Reproduction is mainly asexual (binary fission), but some, like certain algae reproduce sexually.

Fungi

Some are unicellular (e.g., yeasts), others are multicellular (e.g., mushrooms and molds).
All fungi have true nuclei and are eukaryotic.
Cell walls consist of chitin.
Fungi lack chloroplasts and are heterotrophic.
Most are saprophytes, living on dead organic matter (e.g., bread mold and mushrooms).
Some are parasitic, feeding on living material.
Bodies of multicellular fungi are made up of threads called hyphae, which collectively form a mycelium.
Hyphae are often multinucleate.
Fungi reproduce both sexually and asexually.
Asexual reproduction in unicellular fungi like yeasts occurs through budding.
In multicellular fungi, asexual reproduction is by means of spores.

Description

This quiz explores the fascinating world of microorganisms, focusing on viruses and bacteria. Learn about their structures, reproduction methods, and roles in ecosystems. Whether you're studying for a class or just curious, this quiz covers essential characteristics and examples.