BIOL 1111 Lecture Notes - Lecture 5: Necrotizing Fasciitis, Streptococcal Pharyngitis, Myxobacteria
13 Jun 2018
School
Department
Course
Professor
Bacteria
-more than a dozen evolutionary branches in the domain bacteria
-use rRNA for classification (regions with different rates of evolution)
-e’re fousig o 5 gra-negative and 1 gram-positive
1. Proteobacteria
-gram negative
-Purple in colour due to distinctive chlorophyll (photosynthesis is still carried out, but they absorbs green
light and reflect purple)
-some photoautotrophic (purple sulphur- uses sulfur in photosynthesis as a source of electrons)
-some photoheterotrophic (purple non-sulphur; he udergo photosthesis the do’t use ater or
release oxygen, but instead use hydrogen gas primarily as a source of electrons
-some chemoheterotrophs (E. coli, bacteria causing human diseases, myxobacteria), loss of
photosynthesis ability; obtain energy and carbon from organic sources (this is a derived trait)
Myxobacteria
-form colonies held together by slime
-secrete an enzyme to digest other bacteria using quorum sensing
-when conditions are unfavourable for growth/reproduction, this triggers a process to form fruiting
bodies that disperse spores to form new colonies (spores protect DNA from extreme conditions)
-when the environment changes back to be favourable, the spore germinate and a new cell forms
-soe ateria do’t have this mechanism but can still survive in unfavourable conditions
2. Green Bacteria
-gram negative photosynthetic bacteria
-green in colour due to distinctive chlorophyll
-Photoautotrophs: related to archaea and usually found in hot springs
-Photoheterotrophs: in marine and high-salt environments
-do’t release oge durig photosthesis
3. Cyanobacteria
-gram negative photoautotrophs
-blue-green in colour
-carry out photosynthesis similar to plants/algae; use water and release oxygen
-ancestors changed the atmosphere from reducing to oxidizing, which in turn led to selection of aerobic
organisms
-able to do nitrogen fixation (in heterocyst)
4. Gram positive Bacteria
-primarily chemoheterotrophs
-many pathogenic species (disease causing)
ex. Anthrax
Staphylococcus (food poisoning, toxic shock syndrome, pneumonia, meningitis)
Streptococcus (strep throat, pneumonia, necrotizing fasciitis)
-some beneficial species (ex. Lactobacillus (lactic acid fermentation))
Mycoplasmas: naked cells that have lost their cell walls
-stain gram negative due to no peptidoglycan layer
find more resources at oneclass.com
find more resources at oneclass.com
Document Summary
More than a dozen evolutionary branches in the domain bacteria. Use rrna for classification (regions with different rates of evolution) (cid:449)e"re fo(cid:272)usi(cid:374)g o(cid:374) 5 gra(cid:373)-negative and 1 gram-positive: proteobacteria. Purple in colour due to distinctive chlorophyll (photosynthesis is still carried out, but they absorbs green light and reflect purple) Some photoautotrophic (purple sulphur- uses sulfur in photosynthesis as a source of electrons) Some photoheterotrophic (purple non-sulphur(cid:895); (cid:449)he(cid:374) u(cid:374)dergo photos(cid:455)(cid:374)thesis the(cid:455) do(cid:374)"t use (cid:449)ater or release oxygen, but instead use hydrogen gas primarily as a source of electrons. Some chemoheterotrophs (e. coli, bacteria causing human diseases, myxobacteria), loss of photosynthesis ability; obtain energy and carbon from organic sources (this is a derived trait) Secrete an enzyme to digest other bacteria using quorum sensing. When conditions are unfavourable for growth/reproduction, this triggers a process to form fruiting bodies that disperse spores to form new colonies (spores protect dna from extreme conditions)
