Part 1: Introduction Flashcards
What are the three levels of geomicrobiological study?
1) Synecology
2) Demecology
3) Autecology
Define synecology.
Turnover of matter in an entire ecosystem.
e.g. primary production (CO2 fixation) and secondary production (biomass production by heterotrophs)
Define demecology.
Processes performed by a single population or physiological guild - e.g. methanogenesis by methanogens.
Define autecology.
Investigation of a single species, usually in pure cultures - lab-based study.
What are the problems with the autecological method of studying geomicrobiology?
Lab conditions do not reflect natural conditions:
1) Substrate too concentrated
2) In nature multiple substrates will be available
3) In nature more than one species will be present
4) In nature there is spatial heterogeneity
5) Lab cannot reflect seasonal and diurnal temp/radiation changes
What are the problems with the synecological method of studying geomicrobiology?
1) Use of articificial substrates - e.g. flourescentally-labelled amino acids.
2) Perturbation during sampling - e.g. raising from depth
3) Alteration of natural concentrations -e.g. 14C-labelled glucose
What is a prokaryote?
A single-celled organism lacking nuclei, mitochondria and other membrane-bound organelles.
What are the 2 subdivisions of prokaryotes?
Archaea and bacteria
Name 3 global biogeochemical cycles driven solely by prokaryotes.
1) Nitrogen cycle - nitrogen fixation and dentrification
2) Sulphur cycle - sulphate reduction and anoxygenic photosynthesis
3) Carbon cycle - methanogenesis and methan oxidation
What were the first organisms to produce O2 and trigger the great oxidation event?
Cyanobacteria.
What is the Llyn Marguis theory on endosymbiosis?
The theory suggests that a major organisational event in the history of life led to the merging of lineages through symbiosis.
i.e. components of eukaryotic cells are actually engulfed prokaryotes.
What vitamin can only be processed by prokaryotes?
Vitamin B12 - therefore eukaryotes are reliant on prokaryotes.
What is the estimated number of prokaryotes on Earth?
5 x 10^30
Do micro-organisms have differentiated cells?
No - an organism with differentiated cells cannot be considered a prokaryote.
Where do ribosomes, DNA and enzymes exist in a prokaryotic cell?
They are free in the cytoplasm of the cell or in the cytoplasmic membrane.
What are the 5 major components to label on a prokaryotic cell?
1) Cell wall
2) Cytoplasmic membrane
3) Cytoplasm
4) Ribosomes
5) Nucleiod
What are the 10 major components of a eukaryotic cell?
1) Cell wall
2) Cytoplasmic membrane
3) Cytoplasm
4) Ribosomes
5) Chloroplasts
6) Endoplasmic reticulum
7) Mitochondrion
8) Nuclear membrane
9) Nucleus
10) Nucleolus
To what is the prokaryotic cell membrane impervious?
Ions (e.g. Na+) and hydrophilic compounds (amino acids, glucose).
What type of compounds are required for uptake of solutes and give an example of such a compound.
Uptake proteins are required - e.g. phototransferase for uptake of sugars.
Which compounds can freely move across the cell membrane?
1) Gases
2) Water
3) Hydrophobic compounds (e.g. fatty acids)
4) Lithophilic compounds (.e.g benzoic acid)
Why must the cell membrane be kept in a viscous state?
To allow free protein movement, since proteins must be able to make contact with one another for many processes e.g. the respiratory chain.
Viscosity = low, then membrane disintegrates Viscocity = high, then membrane is too rigid
In a diagram of a cell membrane are hydrophilic/hydrophobic protein groups on the inner or outer membrane?
Hydrophilic = outer Hydrophobic = inner
What is a ribosome?
A cellular structure where genetic info (mRNA) is transcribed to the amino acid sequence of a protein.
Where in the cell are enzymes and structural proteins formed?
In the ribosomes.
What are the two subunits of prokaryotic ribosomes?
30s and 50s.
What is a “nascant protein”?
A protein being formed in the ribosomes.
How is the integral, 3D structure of a cell maintained?
Through ionic interactions (Van-der-Waal’s forces / H-bonds) and disulphide (covalent) bonds.
What is the simplified Redfield ratio?
C106 N16 P1
What % of a cell is made up of macromolecules and what are these macromolecules?
96%
1) Proteins (50%)
2) Polysaccharides (10-40%)
3) Nucleic acid (10-20% RNA / 3% DNA)
4) Lipids (10%)
What % of a cell is made up of soluble compounds and what are these soluble compounds?
4%
1) Osmoprotectants
2) Building blocks
3) Coenzymes
4) Polyamines
5) Inorganic ions
What % of a cell (wet weight) is water?
80%
