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
