Proteins and Enzymes

ID #2330

Could you please tell me True or False for those statements below, and give me an example for each one. Thanks 1. a. All condensation rxns are anabolic rxn? b. All Anaybolic rxns are condensation rxn? 2. a. All catabolic rxns are hydrolysis? b. All hydrolysis rxns are catabolic rxn? 3. a. All biosynthetic rxns are endergonic rxn? b. All catabolic rxns are exergonic rxn?


1a. All condensation rxns are anabolic rxn? 
This is true or correct. All condensation reactions are anabolic reactions. To understand why, it's important to know what it means to be a condensation or an anabolic reaction. 
A condensation reaction is a chemical reaction that joins two monomers together and produces water as a product. The really important part that distinguishes this type of reaction from other types of reactions is that water is the product of a condensation reaction. Where did the water come from? It came from each of the two monomers in the reaction losing an H or an OH when the bond was formed between the two of them. 
An anabolic reaction (also called a biosynthetic reaction) combines two monomers together to create a macromolecule. 
Both are examples of ways to go from small to big, and it is true that a condensation reaction always fits in the larger category of anabolic reactions. 
An example of a condensation reaction that is an anabolic reaction is when two amino acids join together to form a dipeptide. You see the peptide bond is formed (anabolic) and the reaction results in the loss of water (condensation). See one of the slides from lecture 4 for an illustration of this example. 
1b. All anabolic rxns are condensation rxn? 
This is false or incorrect. Not all anabolic reactions are condensation reactions. Sometimes you can create bonds without the loss of water. For example, redox reactions in glycolysis involves stripping hydrogens off of the substrate and giving them to NAD+. So, this is an example of going small to big (by forming a new covalent bond between the hydrogen and the NAD+) without losing water (so its anabolic but not a condensation reaction). 
Side note: that example is in the information that you'll learn for exam 2 after the cutoff slide on exam 1 material, but Prof Mehrtens mentioned it in lecture 6 as an example for why not all anabolic reactions are condensation reactions. 
2a. All catabolic rxns are hydrolysis? 
This is false or incorrect. Let's understand what the two types of reactions are first. 
A catabolic reaction is a type of reaction where a bond in a macromolecule is broken to release monomers. 
A hydrolysis reaction uses water as a reactant to break a bond in a macromolecule to release monomers. 
All catabolic reactions are not hydrolysis reactions because of the same example with NAD+. Once NAD+ has gotten to the location where it needs to drop off its cargo, the bond between the hydrogen and NAD+ is broken without using water to break it. So, it is a catabolic reaction, but it is not a hydrolysis reaction. 
2b. All hydrolysis rxns are catabolic rxn? 
This is true or correct. All hydrolysis reactions are catabolic reactions because in both types of reactions bonds are being broken. 
An example of a hydrolysis reaction the is a catabolic reaction is the animation on the course website on the lecture material link under lecture 6. In that animation you can see water being added across the bond of a disaccharide to break it. 
3a. All biosynthetic rxns are endergonic rxn? 
This is true or correct. We already covered what a biosynthetic reaction is in post 1a. An endergonic reaction is a reaction that requires energy. 
Since a bond is stored energy, then forming the bond in a biosynthetic reaction requires energy. So, all biosynthetic reactions (going from small to big) are endergonic (require energy). 
3b. All catabolic rxns are exergonic rxn? 
This is true or correct. We covered catabolic reactions in 2a. An exergonic reaction is a type of reaction that releases energy. 
Since bonds are a storage of energy, breaking a bond in a catabolic reaction (going from big to small) is a type of reaction that is exergonic (releases energy). 

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