Chapter 14 - Chemolithotrophy and Nitrogen Metabolism

Question 1

Chemolithotrophy

Answer 1

Oxidation of inorganic chemicals for generation of energy. Can use oxidative phosphorlyation, but now the substance being oxidized (donor) is inorganic.

Question 2

Hydrogen Oxidizers

Answer 2

These organisms use Hydrogen (H2) w/ the use of hydrogenase. Both aerobic and anaerobic exist.

Question 3

Sulfur Oxidizers

Answer 3

organisms capable of oxidizing wide variety of reduced and partially reduced sulfur compounds such has H2S, So, S2O32 and SO32-. Sulfate is frequently a by-product. Occurs in a step-wise fashion w/ help of Sulfite oxidase enzyme

Question 4

Nitrogen Oxidizers

Answer 4

oxidation of NH3 (ammonia) is performed as a two step process by nitrifying microbes where 1 oxidizes ammonia (NH3) to nitrite (NO2) and second oxidized nitrite to nitrate (NO3). Called Nitrification.

Question 5

Iron Oxidizers

Answer 5

oxidize ferrous iron (Fe2+) and ferric iron (Fe3+).

Question 6

Anaerobic Respiration versus Aerobic Respiration ATP production

Answer 6

Anaerobic does not make as much ATP, and the amount depends greatly on the donor and acceptor being used. Smaller distance between the two, less ATP created.

Question 7

Chemolithoautotrophs

Answer 7

Fix atmospheric Co2 to assemble organic compounds they need. Require reducing power to convert oxidized Co2 into reduced organic compound.

Question 8

Chemolithoautotrophs using electron donors with higher redox potential than NAD+, then…

Answer 8

they need to reverse electron flow and push the electrons back up the tower. Energetically unfavorable

Question 9

Chemolithiheterotrophs

Answer 9

use inorganic chemical for their energy and electron needs, but rely on organic chemicals in the environment for the carbon needs.

Question 10

Mixotrophs

Answer 10

Require both inorganic and chemical compounds for the growth and reproduction

Question 11

Nitrogen Cycle

Answer 11

Depicts different ways in which nitrogen is used and converted by organisms for various purposes.

Question 12

Nitrogen Fixation

Answer 12

Conversion of dinitrogen gas N2 into NH3 Ammonia. Performed by diazotrophs. Very energy intensive process in order to break triple bonded N2 and reduce to NH3. Occurs Anaerobically.

Question 13

Diazotrophs

Answer 13

limited number of bacteria and archaea that can grow without external source of fixed nitrogen, because of their abilities.

Question 14

Nitrogenase

Answer 14

Enzyme required for Nitrogen Fixation - Inactivated by Oxygen. Therefore Nitrogen fixation must occur anaerobically

Question 15

Symbiotic Nitrogen-Fixing Organism

Answer 15

bacteria that partner up with a plan and provide them with an environment appropriate for functioning of their nitrogenase enzyme.

Question 16

Rhizobium

Answer 16

Bacteria that partners up with legume family to create a symbiotic relationship for nitrogen fixation

Question 17

Free Living Nitrogen organisms

Answer 17

both bacteria and archaea, fix nitrogen for hteir own use that ends up being shared when they die.

Question 18

Cyanobacteria

Answer 18

multicellular bacteria that make specialized cells known as heterocysts in which nitrogen fixation occurs. Heterocysts allow for an anoxygenetic version of photosynthesis occur to allow nitrogenase to remain active. They then share the nitrogen with it’s surrounding cells while the surrounding cells provide nutrients.

Question 19

Assimilation

Answer 19

Reductive process where inorganic form of nitrogen is reduced to organic nitrogen compounds such as amino acids.

Question 20

Ammonia Assimilation

Answer 20

occurs when Ammonia (NH3) formed during nitrogen fixation is incorporated into cellular nitrogen.

Question 21

Assimilative Nitrate Reduction

Answer 21

Reduction of nitrate to cellular nitrogen, in a multi-step process where nitrate is reduced to nitrite, then ammonia and finally into organic nitrogen.

Question 22

Nitrification

Answer 22

Performed by chemolithotrophs using a reduced or partially reduced form of nitrogen as an electron donor to obtain energy.

Question 23

Denitrification

Answer 23

Reduction of NO3- to gaseous nitrogen compounds, such as N2.

Question 24

Denitifying microbes perform…

Answer 24

anaerobic respiration, using NO3- as an alternate final electron acceptor.

Question 25

Dissimilatory Nitrate Reduction

Answer 25

Nitrite reduced during energy conservation, not for purposes of making organic compounds. Creates large amounts of excess byproducts, resulting in the loss of nitrogen from local environment into atmosphere

Question 26

Anammox/anaerobic ammonia oxidation

Answer 26

performed by marine bacteria - utilize nitrogen compounds as both electron acceptor and donor. Removes nitrogen from local environment and releases into atmosphere.

Question 27

Anammox acceptor and donor?

Answer 27

oxidized anaerobically as the electron donor while nitrite is utilized as the electron acceptor, N2 as byproduct

Question 28

anammoxosome

Answer 28

specialized cytoplasmic structure which constitutes 50-70% of total cell volume.