Understand enzyme structure and purpose - AP Biology

GLUT1 is a protein that allows glucose to pass into a cell through the membrane. Glucose is a large polar molecule, meaning that it will require a protein in order to diffuse across the membrane. GLUT1 must span the entire length of the plasma membrane in order to provide a "passage" for glucose to diffuse. As a result, GLUT1 is classified as an integral protein, or a protein that fully transverses the membrane.

Peripheral, or extrinsic proteins, are situated on the surfaces of membranes, and do not span across the bilayer. Enzymes catalyze biological reactions; GLUT1 is a transport protein, and does not catalyze any reactions.

Enzymes are biological catalysts that increase the rate of a chemical reaction. This is accomplished by lowering the activation energy for the reaction. Enzymes increase the rate of a reaction, but do NOT increase the amount of products formed in the reaction. They simply cause the products to be formed faster.

A catalyst speeds up the rate of a reaction by lowering the activation energy, which is caused by the high energy transition state. Enzymes are a class of catalyst specific to biological processes, accelerating these processes by lowering activation energy and transition state energy. Catalysts and enzymes may help reactions move faster, but they do not affect the final equilibrium amounts of reactants and products.

While some proteins (such as histones) can pass down information from generation to generation, typically DNA is the macromolecule associated with encoding information.

Proteins commonly catalyze reactions. When these reactions occur in a biological organism, the proteins are considered enzymes. Proteins can also be embedded in cellular membranes, acting as channels or receptors to allow molecular transport. One protein, tubulin, is used to build cilia and flagella (as well as microtubules) that are essential to cell motility.

Proteins are organic molecules made of amino acids that are capable of interfacing with certain substrates and facilitating cellular activities. Enzymes are a sub-group of proteins that are used to speed up reactions within the body. Enzymatic proteins are essential to many biological and cellular processes, such as cellular respiration, transcription, and DNA replication.

Pepsin is an enzyme in the stomach that digests proteins. Because it is active in the stomach, which is highly acidic, pepsin best functions at a low pH between 2 and 2.5.

Pepsinogen is secreted by chief cells and converted into active pepsin after catalyzation by hydrochloric acid. The acid is secreted by parietal cells in response to gastrin secretion by G cells. After the stomach contents enter the duodenum of the small intestine, the acid is neutralized by bicarbonate secretions from the pancreas. This prevents the acid from damaging the walls of the small intestine.

The correct answer to this question is the products contain less energy the reactants.

The products indeed do contain less energy than the reactants because when a spontaneous reaction occurs, it releases energy, which is used to do work. Energy is released in the form of ATP and heat, not noise. Also an input of energy is required before the reaction proceeds, otherwise the reaction does not proceed.

You should immediately realize that amylase is an enzyme because it ends in "-ase". Remember that enzymes are proteins; therefore they are made up of amino acids. All amino acids contain a carboxylic acid (-COOH), an amine (-NH2), and a hydrogen (-H) attached to the central carbon. Phosphate groups (-PO3) are more commonly found in lipids and nucleic acids, not in proteins. No amino acids contain phosphate groups, though phosphates can be added to certain amino acids to activate certain proteins and enzymes (phosphorylation).

Catalysts are molecules that are capable of increasing reaction speed. Enzymes are a particular subset of catalysts; enzymes are proteins that can aid in biological reactions and are crucial to many metabolic processes that occur in cells. Enzymes lower the activation energy of a given reaction, allowing the reaction to proceed faster. The active site of an enzyme is the region of the enzyme that can bind a substrate, when a substrate collides into the enzyme molecule. Joining of an enzyme and substrate results in a chemical reaction whereby the substrates are converted into products. The active site of an enzyme is specific to the substrate's shape, like a lock-and-key mechanism.

Enzymes are catalysts that function to increase the rate of a reaction. All enzymes are proteins and they are never consumed in a reaction. Another form of biological catalyst is ribozymes, which are made of protein and RNA, but are not classified as enzymes.

Enzymes work by lowering the activation energy of a reaction, which can occur either by bringing reactants closer together or by destabilizing the transition state. They do not affect the equilibirum of the reaction, meaning they do not affect the amount of reactants or products. They simply increase the speed at which products can be formed by reducing the amount of energy needed to power the reaction.

Enzymes are biological catalysts that bind to specific substrates. Enzyme activity is tightly regulated by activators and/or inhibitors. Enzymes will change shape as a result in an induced fit when bound to their substrates, activators, and/or inhibitors. Since enzymes are proteins, environmental changes will affect their activity. For example, high temperatures will denature the protein, rendering the enzyme inactive. Isozymes are a group of enzymes that do not have the exact same amino acid sequence, yet they catalyze the same reactions. Enzymes need cofactors, such as prosthetic groups and/or coenzymes in order to function properly. The precursors to coenzymes are vitamins in the diet.

An organism's metabolism is the sum of its chemical processes. Catabolism and anabolism are different aspects of metabolism. Catabolism refers to the breakdown of organic molecules, producing useable forms of energy, such as ATP. Anabolism refers to the use of energy to build macromolecules such as proteins, nucleic acids and carbohydrates.

Enzymes increase the rate of reactions through stabilizing the transition state, which decreases activation energy.

The stomach is an acidic environment; therefore, one would expect pepsin to be most active at an acidic pH. The answer choice “2” is the most acidic pH. It is also the pH that is generally found in the stomach. Although a pH of 6 is slightly acidic, it is not the pH found in the stomach.

A catalyst is responsible for a decrease in activation energy of a reaction. This allows an enzyme to use less energy to manipulate its substrate into a transition state.

Enzymes are biological molecules that help catalyze reactions by lowering the energy of activation and increasing the rate of a reaction. They can do this by a number of mechanisms including: providing a template for substrates to join together in an efficient manner; distorting a substrate so it approaches the unstable/transition state; and providing a microenvironment conducive to a reaction. Inhibitors and activators can affect enzymes activity by slowing down and increasing enzyme activity respectively.

Enzyme activity can be affected by environmental factors such as temperature and pH. This is because proteins denature and lose their shape at high temperatures and extreme pHs. Most enzymes prefer to act under a temperature close to body temperature. Optimal pH is usually physiologic at pH 6 to 8; however, digestive enzymes prefer lower pH around 2 to 3 (e.g. pepsin, which makes sense because pepsin works in acidic conditions within the stomach).

Enzymes are all proteins, however there are some RNA molecules that have been found to catalyze reactions, but they are termed ribozymes, not enzymes. They speed up reactions by lowering the activation energy of a reaction and do not change the energy states of the reactants or products.