Autotrophy

Question 1

To be a true autotroph

Answer 1

• you have to be able to fix carbon using nonorganic sources of energy

Question 2

chemotrophs

Answer 2

• get energy from inorganic molecules that have electrons in them.

Question 3

inorganic chemicals used in autotrophy

Answer 3

• H2
• NH3
• H2S, S, S2O3,
• Fe2+
• H2, CO2, Formate

Question 4

C. jejuni is not an autotrophic organism because

Answer 4

• it cannot fix carbon

Question 5

mixotrophs

Answer 5

• microorganisms that can use an inorganic energy source but must rely on organic carbon for biomass.

Question 6

pathogens

Answer 6

• get H2 from anaerobies

Question 7

methanogens

Answer 7

• live in anaerobic sediments with H2 evolvers

Question 8

nitrogen fixers

Answer 8

• H2 is an oblique byproduct of N2 fixation

Question 9

Nitrosomas

Answer 9

a chemolitotroph that gets energy from the oxidation of ammonia to nitrite

Question 10

Thiobacillus ferrooxidans

Answer 10

• uses iron and sulfur as its electron donors as oxygen as its acceptor.

Question 11

Geobacter.

Answer 11

uses ferric iron as the electron acceptor.

Question 12

two major classes off phototrophs

Answer 12

• halophilic archaea

- photosynthetics

Question 13

halophilic archaea

Answer 13

• use bacteriorhodopsin to harvest light

Question 14

photosynthetics

Answer 14

• further broken down into two groups depending on whether they use chlorophyll or bacteriochlorophyll

Question 15

bacteriorhodopsin

Answer 15

• contains the light sensitive pigment retinal.

Question 16

retinal mechanism of action

Answer 16

• light activated proton pump
• when light strikes the retinal molecule it undergoes a trans to cis isomerization around carbon 13 and loses the proton
• proton passed through series of aspartate residues that form a channel and finally transferred outside of the membrane
• retinal then isomerize back to the trans form
• generates a PMF to create ATP

Question 17

The light reaction

Answer 17

• creating energy from light, requires light
• uses chlorophyll
• two forms

Question 18

two forms light reaction

Answer 18

• anoxygenic (bacteriochlorophyll)

- oxygenic (chlorophyll a)

Question 19

oxygenic photosynthesis

Answer 19

• uses chlorophyll a
• occurs in plants and cyanobacteria or blue green algae
• uses water as e- donor
• generates O2 and ATP
• generates NAD(P)H directly
• involves mostly noncyclic photophosphorylation
• photosystems I and II

Question 20

Photosystem II

Answer 20

• contains water splitting enzyme that extracts e- from water
• contains manganese, and uses light to remove electrons one at a time from the water
• 4 e- total released
• e- donated to chlorophyll and are energized by a photon, then enter an ETC that pumps protons against PMF to generate ATP
• at end, the e- has lost much of its energy and is delivered to another chlorophyll molecule at the start of PS II

Question 21

Photosytem I

Answer 21

• begins with e- at ground state

- e- energized to higher energy level then passed to ferredoxin and are used to reduce NADP to NADPH

Question 22

Bacteriochlorophyll

Answer 22

• water is not reactant
• Thiorhodaceae uses H2S or other inorganic compound
• Chlorobacteriacea uses H2S or other organic compound
• do not produce O2
• cyclic electron flow

Question 23

Bacteriochlorophyll mechanism

Answer 23

• electrons excited via a photon and travel through ETC of a quinone pool, and b- and c-type cytochromes
• proton gradient set up through Q cycle mechanism
• e- deposited back at same bacteriochlorophyll molecule it started in
• no reducing power made
• electrons must be replaced by external electron donor.

Question 24

Anoxygenic

Answer 24

• Anaerobic conditions
• Bacteriochlorophyll
• Electron donor of H2, H2S, So, organics
• energy produced: ATP through cyclic photophosphorylation

Question 25

Oxygenic

Answer 25

• generates O2
• chlorophyll a
• electron donor of H2O
• energy produced: ATP through noncyclic photophosphorylation
• NAD(P)H directly

Question 26

Carbon fixation

Answer 26

• Calvin-Benson cycle (autotrophs, plants)
• Acetyl-CoA pathway (methanogens and acetogens)
• Reductive Krebs Cycle (Green-sulfur bacteria)

Question 27

Calvin Benson Cycle formula

Answer 27

• 6 CO2 + 18 ATP + 12 NADPH = Fructose-6-phosphate + 18 ADP + 12 NADP+ + 17 Pi

Question 28

Calvin Benson cycle

Answer 28

• Dark Reaction
• most carbons fixed by photosynthetics
• ATP and NADPH produced during light reaction used to reduce CO2 into carbohydrate in dark

Question 29

Rubisco

Answer 29

• carboxylase - most important for calvin cycle

- oxygenase