Topic 10: Diversity of Bacteria & Fungi (Part 1) Lecture 19 Flashcards
metagenomics
prokaryotes, can use metagenomics to identify prokaryotic species in soil and even the human gut (called the microbiome)
plasmid
prokaryotes lacks membrane-bound organelles (contains a PLASMID within the nucleotide)
- a small, circular, double-stranded DNA molecule that carries accessory genes separate from those of a bacterial chromosome
peptidoglycan
what bacterial cell walls are composed of
- Structural carbohydrate composed of sugars cross-linked with short polypeptides
capsule
what a cell wall is surrounded by
- Composed of polysaccharides and/ or protein
fimbriae (sing. Fimbria)
Some prokaryotes also have this
• Hairlike projections to anchor to hosts or substrata
Gram Staining
uses crystal violet dye and iodine, and alcohol rinse, and a final stain of red dye
Gram-positive
bacteria have simple cell walls > peptidoglycan
Gram-negative
bacteria have cell walls < peptidoglycan, but more lipopolysaccarhides
Endospores
are types of resistant cells produced by prokaryotes to survive harsh environments
- Bacterial cell replicates its DNA and surrounds it in a super resistant layer
Taxis
movement towards or away from a stimulus
- b/c prokaryotes can move within the environment
flagellum
prokaryotes can use this to move within the environment
binary fission
what prokaryotes reproduce via
- Under optimal conditions can divide every 1-3 hours
• Nutrient and space availability (quorum sensing), self-poisoning, competition limits colony cell
Obligate aerobes
need O2 for cellular respiration (prokaryotes)
Obligate anaerobes
are poisoned by O2
anaerobic respiration
is the process of producing cellular energy without oxygen (or fermentation)
Facultative anaerobes
use O2 when available but will carry out fermentation or anaerobic respiration when oxygen is absent
nitrogen fixation
prokaryotes can also carry out nitrogen fixation -> converting N2 to NH
heterocysts
prokaryotes have specialised cells called heterocysts in photosynthetic
prokaryotes to carry out N-fixation
microbiome
Diverse nutritional modes allow diverse bacteria to inhabit the human gut (called out microbiome) for prokaryotes
extremophiles
Archaea are prokaryotes that inhabit some of the harshest environments (we call these extremophiles)
Halophile
“salt loving”, live in super haline (salty) places
Thermophile
“heat loving”, thermal vents, geysers, volcanic hot springs (think Yellowstone)
Acidophile
“acid loving”, human gut, volcanic features
Methanogen
release methane (many archea also live in moderate environments)
• Found in marshes, cattle guts (cow farts)
• Important decomposers in the environment