Lecture_Study_Guide__Microbial_Metabolism

Microbial Metabolism- Study Guide

What is the definition of metabolism and its ultimate goal?

Metabolism encompasses all biochemical processes within an organism, with the ultimate goal being to convert food into energy.

Define catabolism and anabolism. What is their relationship?

Catabolism breaks down molecules to release energy, while anabolism builds up molecules, using energy. They are interconnected; catabolism provides energy for anabolism.

What molecule is used to store energy inside the cell?

Adenosine triphosphate (ATP) 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 of ADP to form ATP; it is released via hydrolysis of ATP.

What are enzymes made of, and why is it important?

Enzymes are primarily made of proteins; their structure is crucial for their function in catalyzing reactions.

How can the name of an enzyme indicate its function?

The name of an enzyme often reflects its substrate or the type of reaction it catalyzes, usually ending in '-ase'.

How do enzymes function in terms of activation energy?

Enzymes lower the activation energy required for a reaction to proceed, facilitating faster reactions.

Define substrate, active site, cofactor, coenzyme, apoenzyme, and holoenzyme.

Substrate: the reactant an enzyme acts on; Active site: the region on an enzyme where the substrate binds; Cofactor: non-protein component needed for enzyme activity; Coenzyme: organic cofactor; Apoenzyme: the protein part of an enzyme without its cofactor; Holoenzyme: the active form of an enzyme with cofactor.

Why are vitamins important?

Vitamins serve as essential nutrients and coenzymes in various biochemical reactions.

Why is folic acid important for pregnant women?

Folic acid is crucial for DNA synthesis and proper neural development in the fetus.

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

Optimal temperature and pH enhance enzyme activity, while deviations can lead to denaturation; substrate concentration affects the rate of reactions until saturation occurs.

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

Competitive inhibitors compete with substrates for the active site; non-competitive inhibitors bind elsewhere, reducing overall enzyme activity.

What happens to enzymes after they catalyze a reaction?

Enzymes remain unchanged and can catalyze subsequent reactions.

How do cells save energy and regulate enzymatic activity?

Cells save energy through feedback inhibition and by downregulating enzyme activity when not needed.

Why is ATP crucial for the cell, and how is it generated?

ATP is the primary energy currency of the cell, generated through substrate-level phosphorylation and oxidative phosphorylation.

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

Substrate-level phosphorylation occurs directly in metabolic pathways, while oxidative phosphorylation involves ATP synthesis powered by the electron transport chain.

Why are REDOX reactions important to a cell?

REDOX reactions are vital for energy transfer and the metabolism of nutrients within the cell.

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

Glycolysis: the breakdown of glucose; Krebs cycle: a series of reactions for energy extraction from acetyl-CoA; ETC: a series of proteins transferring electrons to produce ATP; fermentation: anaerobic conversion of sugars to acids, gases, or alcohol.

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

Glycolysis occurs in the cytoplasm; Krebs cycle in the mitochondrial matrix; ETC in the inner mitochondrial membrane; fermentation takes place in the cytoplasm.

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

Prokaryotes have a more efficient metabolic pathway and do not lose ATP synthesizing processes like eukaryotes do during mitochondrial transport.

How does the lack of oxygen inhibit the ETC, and what does this mean for cell metabolism?

Lack of oxygen halts the ETC, preventing ATP production, causing cells to switch to anaerobic processes like fermentation.

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

Fermentation allows cells to regenerate NAD+ from NADH, facilitating glycolysis to continue producing ATP.

Why is fermentation important to prokaryotes?

Fermentation provides a means of energy production in the absence of oxygen, allowing prokaryotes to survive in anaerobic environments.

List the characteristics of fermentation: Oxygen requirement, Final electron acceptor, Total ATP produced, End products.

Oxygen requirement: None; Final electron acceptor: organic molecules; Total # of ATP produced: 2; End products: varies (e.g., ethanol, lactic acid).