Ch.7- MIMG

Describe why ATP, FAD, NAD+, and NADP+ are important in a cell.

ATP, FAD, NAD, and NADP+ all play a huge role in metabolism. Specifically, carbohydrate metabolism. This metabolism involves the breakdown of carbohydrates which releases energy aka Glycolysis. Specifically, glycolysis produces ATP and reduces NAD+ to NADH while oxidizing glucose to pyruvic acid. In the Kreb cycle, ATP is produced and NAD+ and FADH2 are reduced. The NADH and FADH2 both carry electrons to the ETC. In the ETC, the energy of electrons is used to produce a great deal of ATP.

Which of the following is the purpose of fermentation? A. to produce carbon dioxide B. to produce large quantities of additional energy C. to regenerate NAD + D. to regenerate oxygen

C

Compare and contrast the overall pathways and relative yields of glycolysis, fermentation, aerobic respiration, and anaerobic respiration.

Glycolysis: -investment step --> 2 phosphorylation steps and requires ATP -pay-off step--> 1 oxidation-reduction step - requires NAD+ and 2 phosphorylation steps generate ATP- 4 ATPs produced, 2 NADH produced, 2 Pyruvate produced -DOES NOT REQUIRE OXYGEN Fermentation: -Does not need oxygen -oxidation of NADH produced by glycolysis -pyruvate or derivative used as an organic electron acceptor Aerobic respiration: -Needs oxygen -The final electron acceptor in the electron transport chain is molecular oxygen (O2). Anaerobic respiration: -The final electron acceptor in the electron transport chain is not O2, but instead is: nitrate, sulfate, or carbonate ion. Yields less energy than aerobic respiration. *aerobic respiration, anaerobic respiration, and fermentation are all possible pathways that can happen after glycolysis* *respiration yields more energy than fermentation (because O2 is the best electron acceptor)*

Create an experimental strategy to determine the carbohydrate catabolism capabilities for an unknown organism. This may contain multiple steps, but be as efficient as possible

I would probably begin with the Oxidation-Fermentation test to differentiate oxidation of glucose from fermentation, and depending on that answer I would perform tests such as Phenol Red, MR-VP, Citrate, TSIA slant, etc to see which carbohydrate sources the organism is able to utilize

Anabolic vs catabolic reactions.

In catabolic reactions, we see the break down of organic compounds (large molecules to small molecules). This process releases ATP. On the other hand, anabolic reactions involve the synthesis of organic compounds (formation of large molecules from small molecules). This process spends ATP.

Given environmental conditions and nutrient sources, predict which energy pathway an organism may use.

-After glycolysis, depending on whether there is oxygen present or not, it can either go through respiration or fermentation -If it chooses to do aerobic respiration, it will go through the Kreb cycle, then go through oxidative phosphorylation in the ETC where we have chemiosmosis, and then produces ATP -OR if it goes through fermentation (alcohol fermentation, lactic acid, etc)

Explain why and how two tubes must be prepared for each organism for the Oxidation-Fermentation (O-F) Test.

-O/F glucose test is one of the best tests to distinguish oxidation of glucose (respiration) from fermentation. 2 test tubes (green deeps) containing glucose are used. One is covered with mineral oil, whereas the other one is exposed to air. If glucose broken down: medium will turn yellow (due to the change in color of the pH indicator (bromothymol blue)) -if open tube turns yellow (organism relies on oxidative phosphorylation) and cover tube is still green, this is oxidative metabolism -if the open tube changes to yellow and the covered tube changes to yellow --> fermenting organism -if both stay green --> glucose is NOT metabolized

Explain how the end products of fermentation can be used to differentiate between bacteria.

-different end products can lead to identification -end products can you what type of fermentation we had -Ex: an end product of lactic acid can hint at a lactic acid pathway and be associated with something such as lactobacillus or streptococcus *look at chart on slides*

Interpret the results of differential tests (O-F, Phenol Red, MR-VP, Catalase, Oxidase, Citrate, etc.) to predict the metabolic capabilities of an organism.

-oxidase test= detects the presence of cytochrome c --> observe color change (purple/blue shows cyto C) -O/F test = distinguish oxidation of glucose (respiration) from fermentation --> 2 test tubes (green deeps) containing glucose are used and one is covered with mineral oil, whereas the other one is exposed to air -MR-VP test = 1. Methyl Red test (MR): Mixed acid fermentation --> positive (red): acidic compounds and negative (yellow): neutral compounds 2. Voges-Proskauer test (VP): produce acetoin and 2,3-butanediol --> positive (red): neutral compounds and negative (yellow): acidic compounds -phenol red test= test for fermentation of different sugars (used to distinguish Salmonella from E. coli)--> each tube contains protein, a single carbohydrate, a pH indicator, and an inverted Durham tube -citrate test= tests whether they can use citrate as sole carbon source or not

What is the final electron acceptor in respiration and fermentation?

-respiration = inorganic final electron acceptor (O2) -fermentation = organic final electron acceptor (pyruvate or acid aldehyde)

Describe in general how the electron transport system generates energy.

A series of electron carriers that are oxidized and reduced as electrons are passed down the chain, from NADH and FADH2 to a terminal electron acceptor. Electrons flow from carriers with more negative redox potential to carriers with more positive redox potential. Energy released can be used to produce ATP.

Explain the role of cytochrome oxidases and what the oxidase test is used to differentiate between.

Cytochrome oxidase transfers electrons from cytochrome to O2. Cytochrome oxidase differs between bacterial types. Some bacteria, such as E. Coli, use cytochrome B instead of C. Thus, this could indicate why kind of bacteria it is. In other words, the presence of different electron carriers is useful for bacterial identification. Oxidase test detects the presence of cytochrome c specifically.

A cell might perform anaerobic respiration for which of the following reasons? A. It lacks glucose for degradation. B. It lacks the transition reaction to convert pyruvate to acetyl -CoA. C. It lacks Krebs cycle enzymes for processing acetyl -CoA to CO 2. D. It lacks a cytochrome oxidase for passing electrons to oxygen.

D