Bacteria and Archaea Flashcards
What do microbes include?
Archaea, bacteria and eukaryotes
They are a range of cell sizes
Who initially discovered bacteria?
Leeuwenhoek - he created some early sketches of what he had been seeing
This contrasted the spontaneous generation theory
What are the key differences between archaea and bacteria?
- Bacteria has ether linkages
- Archaea has ester linkages
- Almost no introns in bacteria - many introns in archaea
What sort of linkages are found in bacteria?
Ether
What sort of linkages are found in archaea?
Ester
What are introns and exons?
Introns = non-coding DNA
Exons = coding DNA
When was the domain archaea established?
In the 1970s - found to be closer to humans than bacteria
Achaea generally found in extreme conditions –> huge genetic diversity
What is the ratio of bacterial cells in the colon?
They outnumber human cells around 10:1
Give 4 examples of how important bacteria are:
- Responsible for many of earth’s processes e.g. photosynthesis & digestion
- No mammal can digest cellulose –> bacteria helps this
- Dealing w waste in sewage farms
- Also cause sepsis & food decay
What are the 4 nutritional & metabolic pathways that bacteria use?
- Phototrophs
- Chemotrophs
- Autotrophs
- Heterotrophs
How do phototrophs survive?
They use light as a source of energy
How do chemotrophs survive?
They use chemical sources of energy
How do autotrophs survive?
Only require CO2 as a source of carbon
How to heterotrophs survive?
One or more organic molecules (e.g. glucose as a source of energy
What are the types of bacteria that we’re familiar with?
- Alpha proteobacteria
- Beta proteobacteria
- Gamma proteobacteria
- Delta proteobacteria
- Epsilon proteobacteria
- Chlamidias
- Spirochetes
- Cyanobacteria
- Gram-positive bacteria
Give an example of an alpha proteobacteria
Rhizobium species live within nodes of roots of leguminous plants
Some species (e.g. Agrobacterium) can produce tutors in plants - used to genetically engineer the plants
What are alpha proteobacteria usually like?
Many species are closely associated w eukaryotic hosts (e.g. Rhizobium species)
- Convert atmospheric N2 compounds the host plant can use
Origin of mitochondria?
What are beta proteobacteria?
- Nutritionally diverse subgroup incl nitrosomonas species
- A wide range of aquatic species
- Some pathogens
What do Nitrosomonas species do?
Play important role in nitrogen recycling by oxidising ammonium (NH4+) to nitrite (NO2-)
A type of beta proteobacteria
What are gamma proteobacteria?
- Auxotrophs including Sulphur bacteria (e.g. Thiomargarita namibiensis) obtain energy by oxidising H2S to sulphur
Some heterotrophic pathogens
Name some of the heterotrophic pathogens under gamma proteobacteria
- Legionella
- Salmonella
- Vibrio
- E.coli
What is delta proteobacteria?
Includes myxobacteria –> congregate into fruiting bodies & release resistant myxospores
Bdelovibrios - small, highly motile bacteria, prey on other bac by invading periplasm & eat them from within
What is epsilon proteobacteria
Incl human pathogens & some non-pathogens (Wollinella species)
Give some examples of the human pathogens used epsilon proteobacteria:
- Campylobacter spices = a major cause of food-born intestinal illness
- Helicobacter pylori = most widely distributed human pathogen causing gastritis, duodenal and gastric ulcers, gastric cancer
What are the chlamydias?
Obligate intracellular pathogen
Includes human pathogens
