Chapter 7: Microbial Metabolism (Down to 7.2 Learning objectives)

For respiration and fermentation what molecules can be used to start the process? What two reasons are why ATP universally chosen?

• Any organic molecules (sugars, lipids, fats, proteins, etc.)

• ATP is universally chosen because the phosphate bonds hold lots of energy and it’s the fastest available way to get energy

What energy production processes can bacteria have? Can they only use 1 process or can they use more than one?

• Bacteria can use aerobic/anaerobic respiration and fermentation (anaerobic)

• Some bacteria use only 1 and some can use them all

What is Metabolism? What are the two types of metabolic rxns?

• Pertains to all chemical reactions and physical workings of the cell (total sum of rxns)

• The two types include anabolism and catabolism

Why is anabolism? Does it make larger or smaller molecules? It requires what? Is it endergonic or exergonic?

• Any process that results in synthesis of cell molecules and structures

• A building and bond-making process that forms larger macromolecules from smaller ones (Ex: AAs into proteins)

• Requires the input of energy (Endergonic) (into the rxn +ATP)

What is catabolism? Does it receive or release energy? Is it endergonic or exergonic? Do all bacteria use the same ways to release energy?

• Breaks the bonds of larger molecules into smaller molecules

• Releases energy (Exergonic)

• Different bacteria use different ways to release energy

Where is energy stored in ATP? What are the two forms of adenosine molecules that deal with energy?

It’s stored in the bonds

• ATP and ADP (ATP holds more energy)

What are the simplified model of metabolism steps?

1. Glucose

2. Catabolism

3. Precursor molecules

4. Anabolism

5. Building blocks

6. Anabolism

7. Macromolecules

8. Anabolism

9. Bacterial cell

What are the first 10 reactions of the catabolism of glucose called? What are the rest of the steps of catabolism of glucose called?

First 10 are glycolysis and the rest are Krebs cycle

What is oxidation? What is Reduction? When a compound loses/gains electrons it’s called what two things? What are these reactions called in general and are they always paired?

• Oxidation: loss of electrons: (gives electrons)

When a compound loses electrons, it is oxidized

• Reduction: gain of electrons: (receives electrons)

When a compound gains electrons, it is reduced

• They are called Oxidation-reduction (redox) reactions and they are paired

What are Oxidation-reduction (redox rxns)? What is the phrase to remember the gain/lose of electrons?

Oxidation-reduction (redox) reactions are common in the cell and are indispensable to the required energy transformation

• When a compound loses electrons, it is oxidized

• When a compound gains electrons, it is reduced

What are Oxidoreductses? Are they in bacteria and humans? What are coenzymes and what are the coenzyme carriers?

• Oxidoreductases: enzymes that remove electrons from one substrate and add them to another (They are in bacteria and human cells)

• Their coenzyme carriers are nicotinamide adenine dinucleotide (NAD+) and flavin adenine dinucleotide (FAD)

• The coenzyme is the non-protein part of the enzyme that helps cause rxns

Do enzyme give electrons to coenzymes? What are the electron carriers apart of the enzyme structure?

• Enzymes give electrons to coenzymes

• Their coenzyme carriers are nicotinamide adenine dinucleotide (NAD) and flavin adenine dinucleotide (FAD)

• Electron carriers are apart of the enzyme structure

Why are NADH & FADH2 important? What do they turn into?

They store electrons and provide them when electrons are needed for reactions

• NADH → NAD+

• FADH2 → FAD

What is reducing power? When are they produced, and when are they needed?

• Reducing power: electrons available in NADH and FADH2

• Produced during catabolism and needed in large quantities for anabolism

What are the three metabolic pathways? List them in most to least energy efficient and which will grow the most.

1. Aerobic respiration (grow the most)

2. Anaerobic respiration

3. Fermentation (grow the least)

What steps of aerobic/anaerobic respiration are the same? Are glycolysis and Krebs straight or cyclical pathways?

Glycolysis and Krebs cycle are the same

• Glycolysis is straight and Krebs is cyclical

Which of the three metabolism pathways use the ETC? What are the electron acceptors for all of the pathways?

• Both respirations use the ETC and Fermentation does not use the ETC

• Final electron acceptors: Aerobic respiration = Oxygen (O2); Anaerobic respiration = inorganic compounds (ex: sulfate, carbonate, nitrate); Fermentation = organic compounds (alcohols, acids)

Does fermentation use Krebs or etc?

No

What is aerobic respiration? What does it utilize? What does it rely on? It’s a characteristic of what things?

• A series of reactions that converts glucose to CO2 and allows the cell to recover significant amounts of energy

• Utilizes glycolysis, the Krebs cycle, and the respiratory chain (ETC)

• Relies on free oxygen (O2) as the final electron and hydrogen acceptor

• Characteristic of many bacteria, fungi, protozoa, and animals

What is anaerobic respiration? What does it involve that is the same aerobic respiration? What does it use as terminal electron acceptors?

• Used by strictly anaerobic organisms and others who are able to metabolize with or without oxygen

• Involves the same three pathways as aerobic respiration: glycolysis, the Krebs cycle, and the electron transport chain

• Uses NO3(-), SO4(-2), CO3(-3) (Nitrate, Sulfate, Carbonate) and other oxidized inorganic compounds as terminal electron acceptors

What is fermentation? Is oxygen required? What are the terminal electron acceptors?

• Incomplete oxidation of glucose (glucose not completely broken down and doesn’t absorb all the possible energy)

• Oxygen is not required

• Organic compounds are terminal electron acceptors