Exam 1 Lecture 5-7

Question 1

What is necessary for growth/maintenance of prokaryotes?

Answer 1

1. reducing power
2. biochemical energy
3. electrochemical energy
4. 12 key organic precursor molecules
5. A source of C1 (methyl) groups

Question 2

Which molecules have good reducing power?

Answer 2

NAD+/NADH; NADP+/NADPH; FAD+/FADH; FMN+/FMNH

Question 3

Biochemical energy usually found as:

Answer 3

ATP

Question 4

What is electrochemical energy?

Answer 4

Energy stored as a proton gradient; proton motive force

Question 5

Why are the 12 key organic precursor molecules important?

Answer 5

They are the building blocks for biological polymers.

Question 6

What is the main source of C1/methyl groups?

Answer 6

S-adenosylmethionine (SAM)

Question 7

Chemoorganotrophy

Answer 7

energy produced by breaking down organic compounds (catabolism)
- ex = humans!

Question 8

Chemolithotrophy

Answer 8

energy produced by oxidizing inorganic compounds like H2, NH4+, H2S

Question 9

Phototrophy

Answer 9

Energy produced by harvesting light

Question 10

Respiratory

Answer 10

Energy generated through an electron transport chain located in the cell membrane that surrounds the cell, which participates in a series of Redox reactions.
- Aerobic (O2) vs Anaerobic (NO3, SO4, etc)

Question 11

Fermentative

Answer 11

Oxidation of organic compounds directly coupled to ATP production

Question 12

Important Energy-Rich molecules in Biological systems

Answer 12

Phosphoenolpyruvate (PEP), ATP, G6P, Acetyl-CoA, Acetyl phosphate

Question 13

Examples of high energy bonds

Answer 13

Thioester bond, Anhydride bond

Question 14

Reduction Potential

Answer 14

The greater the distance between the donor and acceptor, the more energy generated (or required) by Redox reaction

Question 15

Example of Great electron donor

Answer 15

Glucose, sulfate ion

Question 16

Example of great electron acceptor

Answer 16

Fe3+, O2

Question 17

NADH

Answer 17

• Carries 2-3 times as much energy as ATP
• Contains adenosine monophosphate ring
• consumes 2H+ to make NADH
• reaction requires energy input from food molecules

Question 18

FAD

Answer 18

• reduced by 2 electrons and 2 protons to make FADH2

- weaker electron donor than NADH

Question 19

What does respiratory metabolism require?

Answer 19

Electron transport chain, e- donor, e- acceptor

Question 20

What does respiratory metabolism generate?

Answer 20

PMF

Question 21

The breakdown of organic compounds produces ____/____

Answer 21

NADH/FADH (chemoorganotrophy)

Question 22

Reaction centers for Electron Transport:

Answer 22

Flavoproteins, Iron-sulfur cluster; Cytochromes-porphyrin ring; Quinone

Question 23

Flavoprotein

Answer 23

Contains isoalloxazine ring (just like FAD does) which is the redox active part

Question 24

Fe/S proteins

Answer 24

4 cysteine residues can coordinate Fe via thiol groups (Fe = redox active)

Question 25

Cytochromes

Answer 25

``` Porphyrin ring (just like heme structure) - also coordinated iron, covalently linked to cysteins of cytochrome proteins ```

Question 26

Quinone

Answer 26

Non protein; hydrophobic; redox active groups part of ETC

Question 27

What happens when ETC is under highly acidic conditions?

Answer 27

ETC changes its complex 1 to instead have NDH-2; blocks extra H+ from entering to prevent membrane damage

Question 28

NDH-2 is a type of...

Answer 28

NADH dehydrogenase

Question 29

What happens when ETC is under low O2 conditions

Answer 29

ETC uses Cyt BD instead of Complex 4 to save O2

Question 30

True or false: energy yield using Cyt BD is the same as usin Complex 4

Answer 30

False. PMF is decreased due to no protons being released here. There is less energy yield with Cyt BD

Question 31

When O2 is gone, how does E. coli respond?

Answer 31

Uses Nitrate reductase complex for anaerobic respiration instead of complex 4. This is because terminal electron acceptor is now nitrate

Question 32

Is anaerobic respiration unique to prokaryotes?

Answer 32

Yes. Usually have alternative electron donors/acceptors

Question 33

How many protons are used to make ATP?

Answer 33

3

Question 34

Why is it important for ATP synthase to be reversible?

Answer 34

Helps to regulate PMF

Question 35

V. cholerae can use a. _____ to generate ATP

Answer 35

Na gradient. This bacteria usually found in environments with high Na conc.

Question 36

PMF is a sum of _____

Answer 36

pH and charge gradients

Question 37

What do chemolithotrophs use as a high energy substrate to generate PMF?

Answer 37

H2

Question 38

Once H2 is split to 2H+ and 2e- in chemolithotrophs, where do the e- go?

Answer 38

Through membrane into cell, used to reduce NAD+ to NADH inside the cell via cytoplasmic hydrogenase.

Question 39

H2 chemolithotrophs are common in ___ and ___

Answer 39

bacteria and archaea

Question 40

What is the terminal e- acceptor in chemolithotrophs?

Answer 40

O2

Question 41

What other substances, besides H2, can be used as inorganic substrates for ETC?

Answer 41

NH4+, NO2-, Fe2+, H2S

Question 42

True or false: obligate fermentors do not need to generate PMF in absence of ETC

Answer 42

False, still need PMF

Question 43

Why are peripheral pathways important in metabolism?

Answer 43

Environment changes quickly and bacteria have to adapt. Use peripheral pathways to break down other substrates to feed into central metabolic pathway

Question 44

Why do chemolithotrophs and phototrophs still have CMP pathways?

Answer 44

Needed to generate 12 precursor metabolites necessary for life

Question 45

Anapleurotic reactions

Answer 45

Used to bypass/reshape the CMP pathways

Question 46

During normal E. coli metabolism, does it use the entire TCA cycle?

Answer 46

No - it isn't all needed. However, this means oxaloacetate has to be constantly made. PEP can be used to help maintain pool of oxaloacetate through AP reaction

Question 47

What if malate is the only growth medium available?

Answer 47

Malate can be converted to pyruvate and allow glycolysis to happen backwards. This helps to ensure all other of the 12 precursors are made

Question 48

Examples of anoxygenic photoautotrophs

Answer 48

Purple bacteria, Green S and non-S, heliobacteria

Question 49

Anoxygenic photosynthesis

Answer 49

P870 (only one photosystem); uses bacteriochlorophyll A; uses only cyclic electron flow

Question 50

What is one main problem with purple bacteria (anoxygenic photosynthesis)?

Answer 50

P870* and Bph are very unstable; oxidation of Bph to form NAD(P)H can't happen, and the quinones aren't high energy enough. It has to use reverse electron flow