Chapter 7: Microbial Metabolism (Fnal step of aerobic respiration and rest of it)i

What is the 4 point scheme of the Aerobic ETC? (FINISH)

Starting Point: NADH & FADH2

End point: O2 (then turns into H2O)

Reducing power produced: Recyles reducing powers

ATP produced: 32-34

What is the 4 point scheme of the Anaerobic ETC? (FINISH)

Starting Point: NADH & FADH2

End point: Inorganic molecules

Reducing power produced: recycling power recycled

ATP produced: 30-32

What is the 4 point scheme of the fermentation? (FINISH AND CHECK)

Starting Point: 2 pyruvates

End point: Alcohols & Acids (Organic Compounds)

Reducing power produced: None (just recycles into NAD+ and FAD)

ATP produced: 2

For aerobic respiration in the ETC what three things react and what do they form? Also where are these things located and what are they catalyzed by?

• electrons from the last electron carrier in the ETC plus protons from the cytoplasm,

• react with oxygen to form a molecule of water

• Catalyzed by enzyme cytochrome oxidase

In aerobic respiration what is a potential side reaction of the respiratory chain? Do some enzymes have enzymes to neutralize the products? If so what are the enzymes?

• A potential side reaction of the respiratory chain is the incomplete reduction of oxygen to the superoxide ion and hydrogen peroxide

• Some bacteria have neutralizing enzymes to deal with these toxic oxygen products:

• Superoxide dismutase

• Catalase

• Some bacteria such as Streptococcus lacks catalase but still grows well in oxygen due to the production of peroxidase (catalase substitute)

In anaerobic respiration what does the terminal step utilize as the final electron acceptor? What catalyzes the reaction and what does it leave left?

• The terminal step in anaerobic respiration utilizes inorganic compounds rather than free oxygen, as the final electron acceptor

• Nitrate reductase catalyzes the reaction, leaving nitrite and water as products

What is Denitrification? What is it an important step in recycling?

It’s where some species of Pseudomonas and Bacillus possess enzymes that can further reduce nitrite to nitric oxide (NO), and even nitrogen gas N2

• Important step in recycling nitrogen in the biosphere

What are the three min inorganic compounds that are the terminal electron receptors in anaerobic respiration? Do any of the anaerobic pathways ever produce as much ATP as the aerobic?

• Sulfate, carbonate, nitrate

• None of the anaerobic pathways produce as much ATP as aerobic respiration (NEVER EVER)

What is fermentation? What is the final electron acceptor? Does it yield small/large amount of ATP? Do the enzymes matter for the end products?

• The incomplete oxidation of glucose or other carbohydrates in the absence of oxygen

• Uses organic compounds as the final electron acceptors

• Yields a small amount of ATP

Who is fermentation used by? Can organisms hold back using the ETC and revert to fermentation? What two reasons why?

• Used by organisms that do not have an electron transport chain or due to lack of appropriate final electron acceptor

• Other organisms can repress the production of electron transport chain proteins when oxygen is lacking in their environment OR to recycle reducing powers

• They can then revert to fermentation

Can pyruvate from glycolysis be an electron acceptor for fermentation? Does it go through acidic/alcoholic fermentation or both? What is recycled in the process?

• Pyruvic acid from glycolysis (or its derivative) can itself become the electron acceptor

• It can continue through alcoholic fermentation (on the left) or acidic fermentation (on the right).

• The NADs are recycled to reenter glycolysis.

Are the organic molecules that are reduced as electron acceptors in fermentation varied? What are the four types of products from fermentation and examples with them?

• The organic molecules that became reduced in their role as electron acceptors are extremely varied, and often yield useful products

1. Alcoholic beverages: ethanol and CO2

2. Solvents: acetone, butanol

3. Organic acids: lactic acid, acetic acid

4. Vitamins, antibiotics, and hormones

What are complex polysaccharides broken into and can those products enter glycolysis?

Complex polysaccharides are broken into component sugars, which can enter glycolysis

For metabolism of non-carbohydrate compounds what are lipids broken down by? Do these enzymes breakdown lipids in or out of the cell and what happens to it? What two things are lipids broken down into and are they converted after broken down?

• Lipids are broken down by lipases, which are enzymes that break down lipids outside of the cell and brought back inside

• Lipids are broken down into glycerols and fatty acids and both are converted into other molecules after being broken down

What happens to glycerol and fatty acids after they are broken down from lipids?

1. Glycerol converted to dihydroxyacetone phosphate (DHAP), which can enter a step midway through glycolysis

2. Fatty acids undergo beta oxidation, whose products can enter the Krebs cycle as acetyl CoA

What are proteins broken down by? Amino groups are removed through what process? What happens to the remaining carbon compounds?

• Proteins are broken down into amino acids by proteases: break down proteins into individuals AAs

• Amino groups are removed through deamination

• Remaining carbon compounds are converted into Krebs cycle intermediates + glycolysis

Does the ETC always occur in the third step? Can Different steps occur simultaneously?

• No the ETC does not always occur third

• Krebs and the ETC can occur at the same time

• Krebs doesn’t need to finish in order to start the ETC

Top Hat Q: what is the final destination for electrons being transferred through aerobic ETC?

Oxygen

Top Hat Q:At the oxygenated surface of the wound, which of the following categories of bacteria can grow? Select all that apply. Strict Aerobe, microaerophile, facultative anaerobe, strict anaerobe

Strict aerobe and facultative anaerobe (and aerotolerant bacteria)

Top Hat Q: what is the final destination for protons pumped across the membrane that are coming inside the cell during aerobic respiration?

H2O

Top Hat Q: During aerobic respiration of glucose, which end products are produced?

CO2 and H2O

Top Hat Q: Which of the following metabolic pathways be used in anaerobic respiration, but NOT in fermentation? Select all that apply. Glycolysis, Krebs cycle, ETC

Krebs and ETC