Part 1: Introduction

Question 1

What are the three levels of geomicrobiological study?

Answer 1

1) Synecology
2) Demecology
3) Autecology

Question 2

Define synecology.

Answer 2

Turnover of matter in an entire ecosystem.

e.g. primary production (CO2 fixation) and secondary production (biomass production by heterotrophs)

Question 3

Define demecology.

Answer 3

Processes performed by a single population or physiological guild - e.g. methanogenesis by methanogens.

Question 4

Define autecology.

Answer 4

Investigation of a single species, usually in pure cultures - lab-based study.

Question 5

What are the problems with the autecological method of studying geomicrobiology?

Answer 5

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

Question 6

What are the problems with the synecological method of studying geomicrobiology?

Answer 6

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

Question 7

What is a prokaryote?

Answer 7

A single-celled organism lacking nuclei, mitochondria and other membrane-bound organelles.

Question 8

What are the 2 subdivisions of prokaryotes?

Answer 8

Archaea and bacteria

Question 9

Name 3 global biogeochemical cycles driven solely by prokaryotes.

Answer 9

1) Nitrogen cycle - nitrogen fixation and dentrification
2) Sulphur cycle - sulphate reduction and anoxygenic photosynthesis
3) Carbon cycle - methanogenesis and methan oxidation

Question 10

What were the first organisms to produce O2 and trigger the great oxidation event?

Answer 10

Cyanobacteria.

Question 11

What is the Llyn Marguis theory on endosymbiosis?

Answer 11

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.

Question 12

What vitamin can only be processed by prokaryotes?

Answer 12

Vitamin B12 - therefore eukaryotes are reliant on prokaryotes.

Question 13

What is the estimated number of prokaryotes on Earth?

Answer 13

5 x 10^30

Question 14

Do micro-organisms have differentiated cells?

Answer 14

No - an organism with differentiated cells cannot be considered a prokaryote.

Question 15

Where do ribosomes, DNA and enzymes exist in a prokaryotic cell?

Answer 15

They are free in the cytoplasm of the cell or in the cytoplasmic membrane.

Question 16

What are the 5 major components to label on a prokaryotic cell?

Answer 16

1) Cell wall
2) Cytoplasmic membrane
3) Cytoplasm
4) Ribosomes
5) Nucleiod

Question 17

What are the 10 major components of a eukaryotic cell?

Answer 17

1) Cell wall
2) Cytoplasmic membrane
3) Cytoplasm
4) Ribosomes
5) Chloroplasts
6) Endoplasmic reticulum
7) Mitochondrion
8) Nuclear membrane
9) Nucleus
10) Nucleolus

Question 18

To what is the prokaryotic cell membrane impervious?

Answer 18

Ions (e.g. Na+) and hydrophilic compounds (amino acids, glucose).

Question 19

What type of compounds are required for uptake of solutes and give an example of such a compound.

Answer 19

Uptake proteins are required - e.g. phototransferase for uptake of sugars.

Question 20

Which compounds can freely move across the cell membrane?

Answer 20

1) Gases
2) Water
3) Hydrophobic compounds (e.g. fatty acids)
4) Lithophilic compounds (.e.g benzoic acid)

Question 21

Why must the cell membrane be kept in a viscous state?

Answer 21

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

Question 22

In a diagram of a cell membrane are hydrophilic/hydrophobic protein groups on the inner or outer membrane?

Answer 22

Hydrophilic = outer
Hydrophobic = inner

Question 23

What is a ribosome?

Answer 23

A cellular structure where genetic info (mRNA) is transcribed to the amino acid sequence of a protein.

Question 24

Where in the cell are enzymes and structural proteins formed?

Answer 24

In the ribosomes.

Question 25

What are the two subunits of prokaryotic ribosomes?

Answer 25

30s and 50s.

Question 26

What is a “nascant protein”?

Answer 26

A protein being formed in the ribosomes.

Question 27

How is the integral, 3D structure of a cell maintained?

Answer 27

Through ionic interactions (Van-der-Waal’s forces / H-bonds) and disulphide (covalent) bonds.

Question 28

What is the simplified Redfield ratio?

Answer 28

C106 N16 P1

Question 29

What % of a cell is made up of macromolecules and what are these macromolecules?

Answer 29

96%

1) Proteins (50%)
2) Polysaccharides (10-40%)
3) Nucleic acid (10-20% RNA / 3% DNA)
4) Lipids (10%)

Question 30

What % of a cell is made up of soluble compounds and what are these soluble compounds?

Answer 30

4%

1) Osmoprotectants
2) Building blocks
3) Coenzymes
4) Polyamines
5) Inorganic ions

Question 31

What % of a cell (wet weight) is water?

Answer 31

80%