topic 3 bacteria and fungi

microorganisms

include bacteria, fungi, protozoa, and some microscopic algae.

acellular agents

We refer to viruses as a

viruses

although also studied in microbiology, are not considered as microbe or microorganism.

Archaea and Eukarya

are more related

bacteria

- Ubiquitous, mostly free-living prokaryotic unicellular organisms that constitutes majority of all prokaryotic microorganisms.
- They play important ecological roles.
- Multiply by binary fission
- Some can cause diseases (pathogenic).
- Has many applications in food production, industrial processes, medicine, biotechnology etc.

archaea

Mostly associated with extreme environments such as geothermal springs, acid mine drainage, etc. - Generally considered to be nonpathogenic

slime layer

- A loose, disorganized layer of extracellular found outside the cell envelope - Aids in motility, obtaining nutrients and adhesion

capsule

- A an intact, well organized polysaccharide layer outside the cell envelope - Most bacteria produce this layer when there is excess in carbohydrates - They are important virulence factor in pathogenic bacteria

glycocalyx

slime layer & capsule

cell wall

Made up of peptidoglycan - Provides structure and rigidity and gives shape to the cell - Can be differentially stained due to structural differences - Its surface has antigenic properties that can trigger immune responses.

outer membrane

A lipid bilayer outside the peptidoglycan of gram negative bacteria. - Like the cell membrane it is also selectively permeable membrane. - Contains many antigenic components like endotoxin LPS

cell membrane

- the site of electron transport system (oxidative phosphorylation) other processes such as photosynthesis in bacteria. - Encloses the cytoplasm and controls the entry and exit of substances.

cytoplasm

- The site of most metabolic processes e.g., glycolysis and Krebs Cycle inside a bacteria

ribosome

- Site of protein synthesis - Due to the absence of a nuclear envelope the transcription and translation process inside a prokaryote can happen concurrently

endospores

- highly resistant dormant structures produce by some bacteria when conditions are not favorable.

Nucleoid

Irregularly-shaped region in a prokaryotic cell that contains most of the genetic material.

Plasmids

Small, circular, extrachromosomal DNA molecule - Separate from the nucleoid and replicates independently - Usually carry genes for advantageous traits like antibiotic resistance.

fungi

- Eukaryotic - Spore-bearing, heterotrophic organisms - Exhibit sexual/asexual reproduction - Has rigid cell wall (chitinous/cellulosic) - Made up of filamentous somatic structure - Has ergosterol in their cell membrane

Mycology

- study of fungi (“mykes” = mushroom)

yeasts

Unicellular, mostly reproduce by budding. - Some would form buds that would fail to detach from its mother cell forming a pseudohyphae.

molds

- Multicellular; reproduce via sexual or asexual spores - Produces hyphae - fundamental tube -like or filamentous structures; true hyphae - Mycelium/mycelia - mat/mass of hypha that makes up the thallus of the fungi