Chapter 7: Microbial Metabolism (Learning objectives Glycolysis 7.3 down to Final step of before aerobic respirarion)

What is the 4 point scheme? NEED TO REMEMBER FOR ALL STAGES OF BREAKING DOWN GLUCOSE

Must remember

1. Starting compound

2. End point

3. How much reducing power is produced

4. How much ATP is produced

What is the 4 point scheme for all stages? Remember for all metabolic processes

Can drugs block glycolysis? All three metabolic pathways start with what and turn glucose into what?

No because all cells even healthy cells use glycolysis

• They all start with glycolysis which turns glucose into two copies of pyrvate

What is the 4 point scheme of glycolysis?

1. Starting compound: Glucose

2. End point: 2 Pyruvates (3-C molecules)

3. How much reducing power is produced (2 NADH)

4. How much ATP is produced (4 produced but 2 NET)

What happens during the intermediate step in between glycolysis and krebs? What is produced during this step?

The 2 pyruvates are converted into 2 Acetyl-Coa molecules which are then the starting point for krebs

• 2 Acetyl-CoA molecules, 2 CO2, and 2 NADH are produced

Does krebs participate in additional chemical transformations after the intermediate step? What is krebs also called?

• It participates in additional chemical transformations while producing the NADH and FADH2

• Sometimes the Krebs cycle is called the “carbon and energy wheel”

What is the 4 point scheme of krebs? (Does not include intermediate)

1. Starting compound: 2 Acetyl-CoA

2. End point: 4 CO2

3. How much reducing power is produced: (6 NADH & 2 FADH2)

4. How much ATP is produced (2 ATP)

What is produced in total from the intermediate step and krebs combined? Where is the complete breakdown of glucose complete?

1. 6 CO2

2. 2 ATP

3. 8 NADH

4. 2 FADH2

• Breakdown is completed at the end of Krebs

What are the two purposes of the ETC?

1. Generate energy/ATP

2. Electron carriers are sent back to NAD+ & FAD

What is the 4 point scheme for the ETC?

1. Starting compound:

2. End point:

3. How much reducing power is produced:

4. How much ATP is produced

The ETC is a special chain of what? What does it receive and from who? What does it do with the electrons?

• A chain of special redox carriers/electron carriers

• Receives electrons from reduced carriers NADH, FADH2 by glycolysis and the Krebs cycle and passes them in a sequential and orderly fashion from one electron carrier to the next

Where is the ETC embedded in bacteria and in eukaryotes?

• Embedded in the cytoplasmic membrane in bacteria

• Housed in eukaryotes within the inner mitochondrial membranes

What are the electron carrier types located in the ETC? Does this amount vary depending on type of bacteria?

• NADH dehydrogenase

• Flavoproteins

• Coenzyme Q (ubiquinone)

• Cytochromes

• Yes, Diverse nature of ETCs in bacteria

What happens to the reduced carriers (NADH & FADH2) when they encounter the first electron carrier in the chain? What is the first electron carrier?

• They transfer electrons and H+ to the first electron carrier

• The first electron carrier is NADH dehydrogenase

What happens simultaneously as electrons are transferred to the electron carriers in the ETC chain? What happens to the charge comparison of the extracellular/intracellular spaces?

• Simultaneous with the reduction of the electron carriers, protons are moved to the outside of the membrane, creating a concentration gradient (more protons outside than inside the cell).

• The extracellular space becomes more positively charged and more acidic than the intracellular space.

What is the original donator of electrons and where do they go to? Where do the H+ ions go specifically after going across the membrane (in between what two things)?

• The original donator of electrons is glucose to NADH & FADH2 then to ETC

• H+ ions go in between the cell wall and membrane before traveling back

What is the proton motive force (PMF)? What happens to the hydrogen ions after PMF is created? What is converted?

• Difference in [Proton] on opposite sides of the plasma membrane (which creates a imbalance)

• Hydrogen ions (protons) sequestered outside the membrane travel back into the cell using the ATP synthase complex (embedded in the membrane) as a channel

• This results in the conversion of ADP to ATP.

What is oxidative phosphorylation and it’s only ATP from what? How much ATP is produced from NADH and FADH2? Why is FADH2 less?

• Oxidative phosphorylation: the coupling of ATP synthesis to electron transport (ONLY ATP from pairing PMF and ETC)

• Each NADH that enters the electron transport chain can give rise to 3 ATPs

• Electrons from FADH2 a later point than the NAD reactions, there is less energy to release, and only 2 AT P s are the result

What is the Final destination for electrons being transferred through ETC?

O2 or inorganic compounds (ex: sulfate, nitrate, carbonate)

What is the final destination for protons pumped across the membrane that are coming inside the cell?

Going into cytoplasm then can go to H2O