Lecture 11: Microbial metabolism

Question 1

How is E. coli diverse to a wide range of habitiats?

Answer 1

1. temperatures
2. Uv light
3. low pH
4. salinity
5. etc.

Question 2

How can bacteria survive for years in an environment without food

Answer 2

populations drops until its at a maintainable level
1. intial lag phase
2. exponential growth phase
3. death phase
4. long-term stationary phase
5.

Question 3

What is chemosynthesis?

Answer 3

Generation of energy through chemical means (much like PHOTOsynthesis)

e.g., energy from hydrothermal vents vvia sulfide

Question 4

What are hydrothermal vents: black smokers

Answer 4

1. first observed in 1977
2. prod. hydrogen sulphide
3. sulphide and oxygen prov. E for bacteria on surface
4. bacteria from the start of the food chain around smoker

Question 5

What is “The Lost City” hydrothermal vent

Answer 5

1. Alkali hydrothermal vent
2. emits methane and hydrogen
3. 90foot chimneys of thick biofilms of archaea using methane and hydrogen as E sources
4. Serpentine mineral structure consists of interconnected chambres about 1 micro across. Possible start of life.

Question 6

What are the most vital elements required for life?

Answer 6

C, O, N, S, P, and trace elements like Fe

Question 7

What is the most essential molecule for life?

Answer 7

H2O

Question 8

What are the two types of energy sources used?

Answer 8

1. Phototrophism: sunlight

2. Chemotrophism: breakdown of molecules

Question 9

How do higher organisms gain their energy?

Answer 9

1. Obtained from O2 and high E carbon sources

2. Plants use high energy wavelengths of light

Question 10

How do bacteria gain their energy?

Answer 10

More versatile

1. various molecules can be used instead of O2 and carbon sources
2. Photosynthetic bacteria can use different E wavelengths

Question 11

What are the energy sources that all life use?

Answer 11

1. ATP to ADP
   a. chemical energy = ~45KJ/mol
   b. used for transport, sensing and
   synthesis e.g., peptide bonds
2. NADH to NAD+ - another form NADPH
   used
   a. reductive energy: E0 = -0.3v,
   ~60KJ/mol

Question 12

What are the two sides of metabolism?

Answer 12

1. Catabolism

2. Anabolism

Question 13

What are fundamental energetic processes/molecules?

Answer 13

1. ATP and NADH are made (directly or
   indirectly) by OXIDATION of energy rich
   molecules
2. Oxidation releases electrons
3. Electrons can’t be stored indefinitely
4. FERMENTATION and RESPIRATION
   used to get rid of excess

Question 14

How does respiration move about electrons?

Answer 14

metabolic pathways where unconnected electron donors and acceptors exchange electrons

Question 15

How does fermentation move about electrons?

Answer 15

Electron donors and acceptors are part of the same metabolic pathway

Question 16

How much energy comes from different microbial reactions?

Answer 16

1. Aerobic: delta G = -2870KJ mol-1 
    (~30ATP)
2. Anaerobic: delta G = -1930KJ mol-1 
    (~20ATP)
3. Lactic acid fermentation: delta G = 
    -195KJ mol-1 (~2ATP)

Question 17

Where is energy generated in bacteria?

Answer 17

1. Cytoplasm
   a. E.g., Fermentation
   b. substrate level phosphorylation
2. Energy generated across the
   cytoplasmic membrane
   a. E.g., oxidative phosphorylation
   b. Respiration

Question 18

What is the role of quinones, quinols and the cytoplasmic membrane to energy production?

Answer 18

1. Quinols and quinones exist as mixed population in living cells
2. Hydrophobic molecules located in in (cytoplasmic) membrane
3. can carry 2e- and 2H+ without changing charge
4. Used to transport electrons and protons across membrane
5. Types include ubiquinol (aerobic), and menaquinol & duroquinol (anaerobic)