Question
_____ Which of the following statement about enzymes are true? (Two correct answers) (A) To be effective, enzymes must be present at the same concentration as their substrates. (B) They increase the equilibrium constant for the reaction, thus favoring product formation. (C) They lower the activation energy for the conversion of substrate to product. (D) They lower the activation energy for the conversion of product to substrate. (E) They ensure that the product is more thermodynamically stable than the substrate. _____ Which of the following about types of chemical reactions catalyzed by enzymes are true (Two correct answers) (A) Dehydrogenase is belonged to oxidoreductase. (B) Kinase is one type of ligase since it adds a phosphate group to its substrate. (C) Ligase requires ATP molecule to work correctly. (D) Chymotrypsin is a protease. (E) Hexokinase (conversion of glucose to glucose-6-phospahte) has one substrate. _____ Which of the following are true about cofactors for enzymes? (Two correct answers) (A) Inorganic metal ions, such as Zn^2+ and Fe^2+, are the examples of cofactors. (B) Cofactors that are covalently bound to an enzyme protein are called prosthetic groups (ex. Heme). (C) An apoenzyme is the protein part of an enzyme that is not catalytically active until a cofactor is bound. (D) All enzymes are proteins. (E) Without cofactors, enzymes could not bind substrate(s). A few hours after the death of an animal, the corpse will stiffen as a result of continued contraction of muscle tissue (called rigor mortis). The phenomenon is the result of the loss of ATP production in muscle tissue. a. In terms of the six-step model of power-stroke provided by ATP, how a lack of ATP in sarcomeres could result in the initiation of rigor mortis? b. The Ca^2+ transporter in sarcomeres that keeps the [Ca^2+]~ 10^-7 M requires ATP to derive transport of Ca^2+ ions across the membrane of the sarcoplasmic reticulum. How would a loss of this Ca^2+ transport function result in the initiation of rigor mortis? Rigor mortis is maximal at ~ 12 hrs after death, and by 72 hrs is no longer observed. Propose an explanation for the disappearance of rigor mortis after 12 hrs. Describe the general procedures for ELISA or immunoblotting.
Explanation / Answer
Ans 1. C) They lower the activation energy for the conversion of substrate to product.
The enzymes are also called as biological catalysts . For the substrates to form products , they need to cross an activation energy barrier . Enzymes lower this barrier and cause more number of substrate molecules to get converted into the products.
