Introduction Flashcards
What limits life on Earth?
Temperature, pH, water availability, radiation, nutrients
Give four examples of Earth processes that are catalysed by microorganisms
Maintaining chemical balance, mineral formation, mineral diagenesis, mineral dissolution
What groups are prokaryotes?
Bacteria and archaea
Describe prokaryotes
No nucleus or organelles, small, no meiosis, single DNA molecule
Describe eukaryotes
Nucleus, organelles (inc. mitochondris, chloroplasts), meiosis, chromosomes
What does meiosis lead to?
Genetic variation
Compare the suitable conditions for prokaryotes versus eukaryotes
Prokaryotes are much less limited by conditions, including temperature, pH, salinity, and organic/inorganic energy sources
Define heterotrophy
Gaining energy and carbon for growth from the oxidation of organic compounds
Define autotrophy
Forming nutritional organic substnaces from simple inorganic substances
Fixing its own nitrogen
Define chemolithotrophy
Gaining enegry from oxidation of inorganic compounds, taking up carbon as CO2, HCO3^-, or CO3^2-
Give six examples of elements needed by microorganisms
Carbon, nitrogen, phosphorus, sulphur, iron, trace elements
What do microorganisms need for the production of ATP?
Electron donor and electron acceptor
What are electron donors? Give two examples
Elements/moleucles that act as oxidising agents
Glucose and Fe(II)
What are electron acceptors? Give an example
Elements/molecules that act as reducing agents
Oxygen
Describe energy metabolism
Electron flow from fuels to oxidants
What causes the stratification of microbial communities?
Some substrates are easier to oxidise/reduce than others
Why is oxygen absent in many sediments?
The metabolism of oxygen generates the most energy so it is used first
What is the cascade of terminal electron accepting processes?
The order in which substrates are reduced during energy metabolism
Give three examples of fuels in energy metabolism
Sunlight, glucose (organic), hydrogen (inorganic)
Give two examples of oxidants in energy metabolism
Fumarate (organic), carbon dioxide (inorganic)
What can energy metabolism be used for?
Remediation of organics/metals
What can anaerobic respiration cause?
Alteration of the physical/chemical structure of sediments
Describe the central dogma
DNA is transcribed to RNA (no Ts), RNA is translated to polypeptides
Describe DNA
Has a sugar phosphate backbone and complimentary strands
Base pairings: A-T, G-T
Describe the primary structure of proteins
Amino acid sequence of polypeptide chain
Describe the secondary structure of proteins
Local interactions between stretches of polypeptide chain produces α-helix or β-pleated sheet
Describe the tertiary structure of proteins
3d structure of entire polypeptide chain
Describe bonding in carbohydrates
The type dictates which polymer is produced
Describe Gram-positive bacteria
Thick outer layer of peptidoglycan (a carbohydrate)
Stains purple (retains stain containing iodine)
Describe Gram-negative bacteria
Thin layer of peptidoglycan is surrounded by lipopolysaccharide and protein
Colourless or the colour of the counterstain (red)
Describe the lipid bilayer of microbes
Each side has a polar head
Embedded with proteins for transport and energy generation
Describe the production of ATP
Charges are separted by a semi-permeable membrane, H+ is pumped out by the e- transport chain, producing protonmotive force (pmf), ATPase converts pmf into energy, allowing H+ to flow back in, this energy is used to synthesise ATP
