5-4: Chemolithotrophs & Phototrophs

Question 1

What is a chemolithotroph

Answer 1

Get energy from oxidizing inorganic molecule (minerals)

Question 2

Where are chemolithotrophs found

Answer 2

Anywhere with a source of reduced inorganic compounds

Question 3

Common electron donors (energy sources) of chemolithotrophs

Answer 3

H2S, H2, Fe2+, NH4

Question 4

Example of chemolithotrophic microbe

Answer 4

Ralstonia eutropha

Question 5

Information about Ralstonia eutropha

Answer 5

G (-) in soil, freshwater
Chemolithotroph using H2, CO2, O2
Has two hydrogenase enzymes

Question 6

What do the hydrogenase enzymes in Ralstonia eutropha do

Answer 6

Split H2 to H+ and donate electrons to produce ATP/NADH

Membrane bound enzyme donates e to quinones in ETC = proton motive force/ATP
Soluble enzyme reduces NAD+ to NADH =reducing power

Question 7

In phototrophs, ATP is generated by …

Answer 7

Photophosphorylation

Question 8

What are oxygenic phototrophs? E.g.?

Answer 8

Generate O2 as a biproduct of photosynthesis
e.g. cyanobacteria

Question 9

What is a phototroph that does not generate O2? Eg?

Answer 9

Anoxygenic phototroph
e.g. green sulfur bacteria

Question 10

What are antenna pigments in phototrophs

Answer 10

Light-harvesting complexes that capture light energy and transfer to a reaction center
Oxygenic = chlorophylls
Anoxygenic = bacteriochlorophylls

Question 11

What are photosynthetic reaction centers

Answer 11

Complexes of proteins and pigments where electrons are excited and transferred to ETC

Question 12

How many bacteriochlorophylls are there? Why are there different ones?

Answer 12

Many, each with different pigmentations/absorption ranges allowing different phototrophs to coexist in same habitat (use different light)

Question 13

Purple bacteria are what kind of phototroph

Answer 13

Anoxygenic

Question 14

Photosynthetic reaction center of purple bacteria contains a

Answer 14

Bacteriochlorphyll (P870)

Question 15

Describe the ETC of purple bacteria

Answer 15

P870 absorbs light E, which goes from weak e donor P870 to strong e donor P870*, which donates e to quinone, enters ETC. ATP synthase makes ATP

Question 16

Electrons from purple bacteria cycle back to P870 and return it to its original state, this is called

Answer 16

Cyclic photophosphorylation

Question 17

What is a Q-type reaction center? eg?

Answer 17

Electrons transferred to a quinone
e.g. purple bacteria

Question 18

If an autotroph lacks an electron donor with a more negative reduction potential than NAD+/NADH how do they generate reducing power

Answer 18

Reverse electron transport - proton motive force used to drive e in opposite direction of ETC = reduce NAD to NADH (takes a lot of E)

Question 19

The two photocenters of oxygenic phototrophs

Answer 19

Photosystem 1 (PSI, P700, FeS-type)
Photosystem 2 (PSII, P680, Q-type)

Question 20

What do the chloroplasts thylakoid membranes contain

Answer 20

Photosynthetic reaction centers

Question 21

who uses the calvin cycle

Answer 21

phototrophic bacteria, chemolithotrophic bacteria, algae, some arachae

Question 22

What does the calvin cycle do

Answer 22

Fix CO2, convert it to organic molecules
Costs ATP and NADH

Question 23

Enzyme for carboxylation step in calvin cycle?

Answer 23

RuBisCO

Question 24

How many carbons go into the calvin cycle, how many are drawn off for biosynthesis

Answer 24

36C in, 6C

Question 25

Draw out slide 15**

Answer 25

ok