1.
What best describes cytochrome P450 isoenzymes?
Correct Answer
B. They are located in the liver and are responsible for oxidative metabolism of a majority of drugs
Explanation
The correct answer is that cytochrome P450 isoenzymes are located in the liver and are responsible for oxidative metabolism of a majority of drugs. This is because the liver is the primary site of drug metabolism in the body, and cytochrome P450 enzymes play a crucial role in the oxidation of drugs, which helps in their elimination from the body. The small intestine also plays a role in drug metabolism, but it is primarily the liver where cytochrome P450 enzymes are predominantly found. Additionally, the term "oxidative metabolism" refers to the process of adding oxygen to a drug molecule, which is a key function of cytochrome P450 enzymes.
2.
What reversibly inhibits HMG-CoA reductase to reduce cholesterol biosynthesis in the liver?
Correct Answer
D. Statins
Explanation
Statins are a class of drugs that reversibly inhibit HMG-CoA reductase, an enzyme involved in cholesterol biosynthesis in the liver. By inhibiting this enzyme, statins reduce the production of cholesterol in the body. Aspirin, diisopropylfluorophosphate (DIFP), and clavulanate are not known to have this inhibitory effect on HMG-CoA reductase.
3.
Which drug is a protease inhibitor?
Correct Answer
D. All of the above
Explanation
All of the drugs listed, Nelfinavir, Sequinavir, and Indinavir, are protease inhibitors. Protease inhibitors are a class of antiviral drugs that work by inhibiting the protease enzyme, which is necessary for the replication of certain viruses, including HIV. These drugs prevent the virus from maturing and infecting new cells. Therefore, all of the listed drugs are protease inhibitors.
4.
What acts by irreversibly inhibiting cyclooxygenase (COX) involved in prostaglandin biosynthesis?
Correct Answer
A. Aspirin
Explanation
Aspirin acts by irreversibly inhibiting cyclooxygenase (COX) involved in prostaglandin biosynthesis. This means that it blocks the action of COX, an enzyme responsible for the production of prostaglandins, which are involved in inflammation, pain, and fever. By inhibiting COX, aspirin reduces the production of prostaglandins, leading to its anti-inflammatory and analgesic effects.
5.
What irreversibly inhibits beta-lactamase?
Correct Answer
C. Clavulanate
Explanation
Clavulanate is the correct answer because it irreversibly inhibits beta-lactamase. Beta-lactamase is an enzyme produced by bacteria that can break down beta-lactam antibiotics, rendering them ineffective. Clavulanate is a beta-lactamase inhibitor that can bind to the enzyme, preventing it from breaking down the antibiotic. This allows the antibiotic to remain active and effectively kill the bacteria. Aspirin, organophosphate pesticides, and statins do not have this inhibitory effect on beta-lactamase.
6.
What irreversibly inhibits acetylcholinesterase?
Correct Answer
B. OrganopHospHate pesticides
Explanation
Organophosphate pesticides irreversibly inhibit acetylcholinesterase. Acetylcholinesterase is an enzyme that breaks down the neurotransmitter acetylcholine, allowing for proper nerve signal transmission. Organophosphate pesticides bind to and inhibit this enzyme, leading to an accumulation of acetylcholine and overstimulation of the nervous system. This can result in symptoms such as muscle weakness, paralysis, and even death in severe cases. Aspirin, clavulanate, and statins do not have this inhibitory effect on acetylcholinesterase.
7.
What converts angiotensinogen into angiotensin l?
Correct Answer
C. Renin
Explanation
Renin is the enzyme responsible for converting angiotensinogen into angiotensin I. This conversion is the first step in the renin-angiotensin-aldosterone system, which plays a crucial role in regulating blood pressure and fluid balance in the body. Renin is released by the kidneys in response to low blood pressure or low sodium levels, and it acts on angiotensinogen to initiate the production of angiotensin I. Angiotensin I is then further converted into angiotensin II by angiotensin converting enzyme (ACE), which is not the correct answer in this case.
8.
What converts angiotensin l into angiotensin ll?
Correct Answer
A. Angiotensin converting enzyme (ACE)
Explanation
Angiotensin converting enzyme (ACE) converts angiotensin l into angiotensin ll. ACE is an enzyme found in the lungs and blood vessels that plays a crucial role in the renin-angiotensin-aldosterone system. This system regulates blood pressure and fluid balance in the body. Angiotensin l is a hormone that is converted into angiotensin ll by ACE. Angiotensin ll is a potent vasoconstrictor that causes blood vessels to narrow, leading to an increase in blood pressure. Therefore, ACE is responsible for the conversion of angiotensin l to angiotensin ll, which ultimately affects blood pressure regulation.
9.
What are chymotrypsinogen and trypsinogen considered?
Correct Answer
B. Zymogens
Explanation
Chymotrypsinogen and trypsinogen are considered zymogens. Zymogens are inactive forms of enzymes that are converted into their active forms through a series of enzymatic reactions. In the case of chymotrypsinogen and trypsinogen, they are converted into the active enzymes chymotrypsin and trypsin, respectively, which play important roles in the digestion of proteins. This activation process helps to prevent the enzymes from causing damage to the cells that produce them, as they are only activated when needed.
10.
Which of the following are coenzymes of coenzymes?
Correct Answer
D. Vitamins
Explanation
Vitamins are coenzymes of coenzymes. Coenzymes are small organic molecules that assist enzymes in carrying out their functions. They bind to enzymes and help facilitate the chemical reactions that enzymes catalyze. Vitamins, such as vitamin B complex and vitamin C, are essential nutrients that are required in small amounts for various metabolic processes in the body. Some vitamins, like vitamin B complex, act as coenzymes themselves, directly participating in enzymatic reactions. However, other vitamins, like vitamin A, function as precursors for coenzymes, meaning they are converted into active coenzymes once inside the body. Therefore, vitamins can be considered coenzymes of coenzymes.
11.
What inorganic ion(s) serve as a cofactor for pyruvate kinase?
Correct Answer
D. A and C
Explanation
Pyruvate kinase is an enzyme involved in the final step of glycolysis, which converts pyruvate into ATP. Inorganic ions such as magnesium (Mg) and potassium (K) can serve as cofactors for pyruvate kinase, enhancing its activity. Therefore, both options A and C, which include magnesium and potassium, are correct answers. Manganese (Mn) is not known to serve as a cofactor for pyruvate kinase, so option B is not correct.
12.
What inorganic ion(s) serve as a cofactor for hexokinase?
Correct Answer
A. Magnesium Mg
Explanation
Magnesium ions (Mg) serve as a cofactor for hexokinase. Cofactors are inorganic ions or non-protein molecules that assist enzymes in carrying out their catalytic functions. In the case of hexokinase, magnesium ions help to stabilize the enzyme-substrate complex and facilitate the transfer of a phosphate group from ATP to glucose during the initial step of glucose metabolism. Therefore, magnesium is essential for the proper functioning of hexokinase.
13.
What inorganic ion(s) serves as a cofactor for ribonucleotide reductase?
Correct Answer
B. Manganese Mn
Explanation
Manganese (Mn) serves as a cofactor for ribonucleotide reductase. This enzyme is responsible for the conversion of ribonucleotides to deoxyribonucleotides, which are essential building blocks for DNA synthesis. The presence of manganese ions is crucial for the activity of ribonucleotide reductase, as they play a role in the catalytic mechanism of the enzyme. Therefore, manganese is necessary for the proper functioning of this important biological process.
14.
What inorganic ion(s) serve as a cofactor for glutathione peroxidase?
Correct Answer
B. Selenium Se
Explanation
Selenium serves as a cofactor for glutathione peroxidase. Cofactors are non-protein molecules that are required for the proper functioning of enzymes. Glutathione peroxidase is an enzyme that helps in the reduction of hydrogen peroxide and organic hydroperoxides by using glutathione as a reducing agent. Selenium is an essential component of the active site of glutathione peroxidase and is necessary for its catalytic activity. Therefore, selenium is the inorganic ion that serves as a cofactor for glutathione peroxidase.
15.
What inorganic ion(s) serve as a cofactor for alcohol dehydrogenase?
Correct Answer
C. Zinc Zn
Explanation
Zinc ions (Zn) serve as a cofactor for alcohol dehydrogenase. Cofactors are non-protein molecules or ions that are required for the proper functioning of enzymes. In the case of alcohol dehydrogenase, zinc ions bind to the enzyme and help in the catalysis of the reaction that converts alcohol to aldehyde. Magnesium (Mg) and selenium (Se) are not mentioned as cofactors for alcohol dehydrogenase, so the correct answer is zinc (Zn).
16.
What enzyme catalyzes group transfer reactions?
Correct Answer
A. Transferase
Explanation
Transferase is the correct answer because transferase is an enzyme that catalyzes group transfer reactions. Group transfer reactions involve the transfer of a functional group from one molecule to another. Transferases play a crucial role in various biological processes, including metabolism and signal transduction. They are involved in transferring groups such as methyl, acetyl, and phosphate, among others. Therefore, transferase is the enzyme that specifically catalyzes group transfer reactions.
17.
What enzyme catalyzes hydrolysis reactions?
Correct Answer
B. Hydrolase
Explanation
Hydrolase is the correct answer because it is an enzyme that catalyzes hydrolysis reactions. Hydrolysis is a chemical reaction in which a molecule is broken down into smaller units by the addition of water. Hydrolases play a crucial role in various biological processes, such as digestion, metabolism, and cellular signaling. They help break down complex molecules, such as proteins, carbohydrates, and lipids, into their respective building blocks through hydrolysis. Therefore, hydrolase is the enzyme that specifically catalyzes hydrolysis reactions.
18.
What enzyme catalyzes the addition of groups to double bonds or formation of double bonds by the removal of groups?
Correct Answer
C. Lyase
Explanation
Lyase is the correct answer because this type of enzyme catalyzes the addition of groups to double bonds or the removal of groups to form double bonds. It is involved in various metabolic processes, such as the breaking down of molecules or the creation of new bonds. Unlike other enzymes listed, lyase specifically focuses on the formation or elimination of double bonds.
19.
What enzyme catalyzes the transfer of groups within molecules to yield isomeric forms?
Correct Answer
D. Isomerase
Explanation
Isomerases are enzymes that catalyze the transfer of functional groups within molecules, resulting in the formation of isomeric forms. Isomerization involves rearranging the atoms within a molecule, leading to the formation of different structural isomers. Therefore, isomerase is the correct enzyme that catalyzes this type of reaction. Transferase enzymes, on the other hand, catalyze the transfer of functional groups between molecules, not within molecules. Hydrolases are involved in hydrolysis reactions, lyases catalyze the addition or removal of groups to form double bonds, and ligases catalyze the joining of two molecules using energy from ATP.
20.
What enzyme catalyzes the formation of covalent bonds by condensation reactions coupled to cleavage of ATP or similar cofactors?
Correct Answer
E. Ligase
Explanation
Ligase is the correct answer because it catalyzes the formation of covalent bonds by condensation reactions coupled to the cleavage of ATP or similar cofactors. Ligases are enzymes that join two molecules together by forming a new covalent bond, often using ATP as an energy source. This process is important in DNA replication, repair, and recombination, as well as in the synthesis of proteins and other molecules.