Lecture Study Guide_ Microbial Metabolism

What is metabolism? What is its ultimate goal?

Metabolism is the sum of all chemical reactions in a cell; its ultimate goal is to convert food into energy.

Define catabolism and anabolism. What is the relationship between these two reactions?

Catabolism refers to the breakdown of molecules to produce energy, whereas anabolism is the synthesis of molecules; they are interconnected as catabolism provides the energy needed for anabolism.

What molecule is used to store energy inside the cell?

ATP (adenosine triphosphate) is used to store energy inside the cell.

What is the process to store energy? What is the process to release energy?

Energy is stored through phosphorylation (forming ATP) and released through hydrolysis (breaking down ATP).

What are enzymes made of? Why is this important?

Enzymes are primarily made of proteins; this is important because their structure determines their function in catalyzing reactions.

How can the name indicate something is an enzyme?

Enzyme names often end in '-ase' which indicates it is an enzyme (e.g., lactase).

How do enzymes function in relation to activation energy?

Enzymes lower the activation energy required for a reaction to occur, thus speeding up the reaction.

Define: Substrate, Active site, Cofactor, Coenzyme, Apoenzyme, Holoenzyme.

Substrate: The molecule upon which an enzyme acts. Active site: The specific region where substrate binds to an enzyme. Cofactor: A non-protein molecule that assists enzyme function. Coenzyme: A specific type of cofactor that is organic. Apoenzyme: The inactive form of an enzyme without its cofactor. Holoenzyme: The active form of an enzyme, with its cofactor.

Why are vitamins important?

Vitamins serve as essential coenzymes or precursors to coenzymes, aiding in various biochemical reactions.

Why is folic acid important for pregnant women?

Folic acid is crucial for DNA synthesis and cell division, which are vital during pregnancy for fetal development.

How do temperature, pH, and substrate concentration affect enzymatic activity?

Temperature and pH must be optimal for enzyme activity; deviations can denature enzymes or alter activity. Substrate concentration affects the rate of reaction until saturation is reached.

Why would you use a competitive or non-competitive inhibitor?

Competitive inhibitors are used to compete with substrates for the active site, while non-competitive inhibitors bind elsewhere, altering enzyme function.

What happens to enzymes after they catalyze a reaction?

Enzymes remain unchanged after catalyzing a reaction and can be reused.

How do cells save energy and regulate enzymatic activity?

Cells save energy through regulatory mechanisms that modify enzyme activity based on metabolic needs.

Why is ATP crucial for the cell and how are they generated?

ATP is essential as it provides energy for cellular processes; it is generated through cellular respiration and substrate-level phosphorylation.

What is the biggest difference between substrate-level phosphorylation and oxidative phosphorylation?

Substrate-level phosphorylation directly generates ATP from ADP by transferring a phosphate group, while oxidative phosphorylation involves electron transport and chemiosmosis.

Why are REDOX reactions important to a cell?

REDOX reactions are crucial for energy transfer in cellular metabolism, involving the transfer of electrons.

Define/explain glycolysis, Krebs cycle, electron transport chain (ETC), and fermentation.

Glycolysis: Breakdown of glucose to pyruvate, producing ATP and NADH. Krebs cycle: Processes acetyl-CoA to produce ATP, NADH, and FADH2. ETC: Uses electrons from NADH and FADH2 to produce ATP. Fermentation: Anaerobic process to regenerate NAD+.

Where does glycolysis, the Krebs cycle, ETC, and fermentation happen, respectively?

Glycolysis occurs in the cytoplasm, Krebs cycle in the mitochondria, ETC in the inner mitochondrial membrane, and fermentation in the cytoplasm.

Why do prokaryotes generate more ATP in carbohydrate catabolism than eukaryotes?

Prokaryotes generate more ATP because they lack mitochondria, allowing them to directly oxidize substrates at the plasma membrane.

Why is the ETC inhibited by the lack of oxygen? How does that affect the cell’s metabolism?

Without oxygen, the final electron acceptor is absent, halting the electron transport chain and leading to decreased ATP production.

Why is fermentation necessary when there is little or no oxygen?

Fermentation allows cells to regenerate NAD+ for glycolysis to continue producing ATP in the absence of oxygen.

Why is fermentation important to prokaryotes?

Fermentation allows prokaryotes to survive and generate energy in anaerobic environments.

Fermentation: Oxygen requirement – Final electron acceptor – Total # of ATP produced – End products –

Oxygen requirement: Anaerobic; Final electron acceptor: Organic molecules; Total # of ATP produced: 2 ATP per glucose; End products: Varies (e.g., lactic acid, ethanol).

What happens to electrons in oxidation and reduction reactions?

In oxidation reactions, electrons are lost; in reduction reactions, electrons are gained.

How many ATP or reduced coenzymes are produced in aerobic respiration?

Aerobic respiration can produce up to 38 ATP per glucose molecule.

What is the starting compound for aerobic respiration?

The starting compound is glucose.

What ATP production methods are involved in aerobic respiration?

Both substrate-level phosphorylation and oxidative phosphorylation are involved.

What is the total number of ATP produced after aerobic respiration?

The total number of ATP produced in aerobic respiration can be up to 38 ATP.

What is the final electron acceptor in aerobic respiration?

The final electron acceptor is oxygen.