Microbes Flashcards
Limit of Vision
- closest eye can focus is around 10cm
- smallest object that we can see is 30um
- around half the things are in the ‘invisible world’, some are also in the shadow world
The development of lenses
1) magnify glass (2x)
2) compound microscope (10x)
3) microscopic cell (150x)
4) microbes (300x)
What are the 2 mechanisms of a cell?
1) metabolism
2) replication
What are the three parts of the cell theory?
1) living tissue is formed of cells
2) cell is site of metabolism and replication
3) all cells come from other cells (fusion/division)
Plasma Membrane
- boundary of the cell
- hydrophilic head group (water)
- hydrophobic tails (no water)
- all in the phospholipid bilayer
- all traffic from outside must take place across the membrane
Define transport, signals, adhesion in terms of the plasma membrane
1) Transport: channels allow passage of specific molecules and ions
2) Signals: receptors bind external ligands and change cell behaviour
3) Adhesion: adhesion proteins hold cells together
What are the two distinct biochemical systems of a cell and tell me about them?
1) Metabolism
- cell generates or harvests energy and channels it to synthesize new biomass
- if there was NO membrane the products would diffuse away
2) Information
- cell stores important information for the metabolic system
- if there was NO membrane both of the systems could not be linked
What happens if metabolic system and information are in the same membrane?
- increase efficiency
- heritable
- replicates more rapidly
Origin of life
1) special creation
- creation of animals
2) panspermia
- undirected: dispersal of microbes planet to planet
- misdirected: planted by aliens
- directed: galactic pollution by space craft
3) spontaneous generation:
- spontaneously appears
- need growth, reproduction, inheritance
What are the two possible routes in the origin of life?
1) genetics first
2) metabolism first
- supplied energy for self replicating systems
Glycosis
- initial stage of energy production
- glucose is broken down into pyruvate, ATP, NADH (reducing power)
Fermentation
- if glycosis does not work because of oxygen or something else is not available, then pyruvate is the final electron acceptor
- NADH reoxidizes so there can be a new round of glycosis, does not generate energy
Respiration and the electron transfer chain
- Glycosis –> citric acid cycle –> electron transfer chain
Electron transfer chain: - electrons passed along chain “downhill”, from more electropositive molecules “electron donors” to more electronegative “electron-hungry”
- This energy released is harvested to do work in the cell
Chemiosmotic energy storage by membranes
energy released by electron transport chain is used to pump protons across the plasma membranes to create electrochemical gradient
Redox Tower
- Describes chemical reaction using electropositive donors and electronegative donors
- bacterial metabolism is based on this
- organisms that use more electronegative acceptors = more versatile cause they can oxidize a higher range of substrates to obtain energy
Define bacterial genome
- Made up of around 5 million base pairs
- formed of single molecule of DNA (closed loop)
Define Plasmids
- small DNA molecules that occur in bacteria, not essential for normal function
Transcription and Translation
- information storage in cell and metabolism are linked by transcription and translation
- Transcription: DNA (information storage in nucleus) -> mRNA (information retrieval in cytoplasm) -> tRNA (product assembly in ribosome)
- Translation= tRNA -> product
Define Coalescent
The point in which a single individual gives rise to all the individuals in the current population
LUCA
- last universal common ancestor, two daughter cells
1) ancestor to all living Eubacteria
2) ancestor to all living Archaea
What are some things that happened at the time of the origin of life?
- endergonic chemical reactions
- RNA world
- self replicating ribosomes
- early cells
- LUCA
- split of bacteria and archaea
Define catabolism
Breakdown of complex molecules in living organism
Evolution of catabolism
- overtime growth depletes the essential substrates, favoured by selection and those ones drive the metabolic pathway
- metabolic pathways start simple and then become much more complicated
- enzymes are specialized for diff functions
Evolution of metabolism
1) Xylitol not transported or metabolized
2) mutation, Ribitol is not repressed but it is constructive and slowly oxidizes Xylitol
3) mutation, Arabitol is not repressed anymore and it is constructive, it increased the activity of Xylitol
NOW A NEW METABOLIC PATHWAY
What are the 3 basic kinds of organisms?
1) bacteria
2) archaea
3) eukaryotes
What are the differences in the plasma membrane between Achaea vs Bacteria + Eukaryotes
1) Archaea:
- do not use fatty acids
- branched side chains of 20 carbon atoms build from isoprene
- side chains bound from ether linkage
2) Bacteria + Eukaryotes
- use fatty acids as side chains
- 16-18 carbon chain
- no side branches
- ester linkage
Difference between Archaea vs Eukaryotes
1) Archaea:
- cell wall
- lacks peptidoglycan
2) Eukaryotes
- cellulose (plants) or chitin (fungi) to strength the cell wall
Two types of Archaea
1) Euryachaeota
2) Crenarchaeota
what is the base of bacteria and what is the base of archaea?
Bacteria: acetate based
Archaea: methane based
Chloroflexi
- Green filaments in hot springs
- used for respiration and photosynthesis
Synechococcus
- marine bacteria
- 10% of global primary production
- uses chlorophyll to capture light energy
Streptomyces
- antibiotics
- filamentous soil bacterium
Bacillus
- common in soil
- causative agent of anthrax
- very resistant
Mycoplasma
- lacks cell wall
- parasites or saprobes
- small - self replicating
Treponema
- disease
- parasites that causes syphilis
Chlorobium
- surface waters of lakes
- green sulphur bacterium
Rhizobium
- Nitrogen fixation
Nitrosomonas
- ammonia oxidation
Escherichia
- symbiosis
- E. Coli
- in gut of mammals, usually harmless, can cause serious disease
