Bacteriology 1 Flashcards
What is the difference between the growth of bacteria in agar compared to broth?
Agar = in colonies Broth = becomes turgid
What are the four stages of bacteria colony growth ?
lag
exponential
stationary
death
What is the microbiota ?
the good bacteria which colonises the body after birth
What is the microbiota relationship with the body?
Symbiotic relationship = protective layer in return for nutrients
high concentration in intestine and mouth
causes disease if in the wrong location in body
Ecoli
Describe taxonomy
- Based on phenotypes (can’t be used to compare bacteria)
- domain, kingdom, phylum
Why is the taxonomical group of bacteria hard to determine?
bacteria has lots of mutations and horizontal transfer
at what point do you say its changed species
Describe phylogeny
Based on DNA sequences
Evolutionary analysis
Find evolutionary distance by phylogenetic trees
What is the 16s rRNA sequence ?
- by PCR
- 1st coli classification
- Shows variable and conserved regions
- able to differentiate bacterial species
What % has to be conserved in the 16s rRNA sequence for bacteria to be the same species ?
97%
What makes bacteria gram positive ?
Thick peptidoglycan layer, stain taken in, purple in colour
What makes bacteria gram negative?
Thin peptidoglycan layer, pink
What are human bacteria gram negative or positive ?
gram positive or proteobacteria
What are the characteristics of protists ?
unicellular (eukaryotes)
reproduced sexually and asexually
Absorb nutrients by wrapping around particle
What are the characteristics of archaea?
Separate from bacteria based on 16s rRNA sequence
no peptidoglycan wall
present in extreme conditions
What are crenarchaea ?
archaea which are hyperthermophilic
