Question

Classify the following types of chemical reactions. a. glucose \(+\) fructose \(\rightarrow\) sucrose \(+\mathrm{H}_{2} \mathrm{O}\) b. lactose \(\rightarrow\) glucose \(+\) galactose c. \(\mathrm{NH}_{4} \mathrm{Cl}+\mathrm{H}_{2} \mathrm{O} \rightarrow \mathrm{NH}_{4} \mathrm{OH}+\mathrm{HCl}\) d. ATP \(\rightleftharpoons \mathrm{ADP}_{+} \mathrm{P}_{\mathrm{i}}\)

Short answer

a. Dehydration synthesis, b. Hydrolysis, c. Ionization, d. Reversible reaction.

Step-by-step solution

Identifying Reaction Type for Part (a)

The reaction given is glucose plus fructose yielding sucrose and water. This is a typical example of a dehydration synthesis or condensation reaction, where two smaller molecules combine to form a larger molecule with the loss of water (H₂O).

Identifying Reaction Type for Part (b)

The reaction involves the breakdown of lactose into glucose and galactose. This is considered a hydrolysis reaction because it involves the breaking down of a molecule (lactose) using water to produce two smaller molecules.

Identifying Reaction Type for Part (c)

In this reaction, ammonium chloride reacts with water to form ammonium hydroxide and hydrochloric acid. This is an example of an ionization reaction in water, where the substance dissociates into different ions or compounds when dissolved in water.

Identifying Reaction Type for Part (d)

The ATP to ADP and Pᵢ reaction is an example of a reversible reaction because ATP can be hydrolyzed to form ADP and an inorganic phosphate, and the process can also reverse where ADP can combine with an inorganic phosphate to regenerate ATP.

Key concepts

Dehydration Synthesis

Dehydration synthesis, also known as a condensation reaction, is one of the essential processes in biology. This reaction occurs when two smaller molecules come together to form a larger molecule, with the removal of a water molecule. This is crucial in the formation of various biological polymers like carbohydrates, proteins, and nucleic acids.

For instance, in the formation of sucrose from glucose and fructose, a water molecule is removed. This bond formation through dehydration synthesis is key in building and storing larger molecules. The removal of water helps to stabilize the newly formed bond. The process is essential for storing energy in the form of larger molecules.

Key Points:

• Involves forming larger molecules from smaller ones.
• A water molecule is removed (dehydrated) during the reaction.
• Crucial for the creation of polymers like carbohydrates and proteins.

Hydrolysis Reaction

The hydrolysis reaction is essentially the opposite of dehydration synthesis. It involves the breakdown of complex molecules into simpler ones by adding a water molecule. This reaction is vital for digestion and energy release within cells.

In the example given with lactose, it breaks down into glucose and galactose by adding a water molecule. The water helps to cleave the chemical bonds in lactose, thereby splitting it into two simpler monomers that can be readily absorbed by the body.

Key Points:

• Decomposition of larger molecules into smaller ones with the addition of water.
• Fundamental for digestion and nutrient assimilation.
• Increases the solubility of molecules, aiding in absorption within organisms.

Ionization Reaction

Ionization reactions involve the conversion of neutral molecules into ions. In biological systems, these reactions are pivotal because they influence enzyme activity, transport across membranes, and more.

For example, the reaction of ammonium chloride with water breaks down into ammonium hydroxide and hydrochloric acid. Here, the ionization in water separates the compound into its respective ions. Such dissociations are crucial for various cellular activities and metabolic pathways.

Key Points:

• Involves splitting of molecules into ions (charged particles).
• Crucial for biochemical reactions and cellular functions.
• Affects pH and enzyme reaction rates inside cells.

Reversible Reaction

Reversible reactions are chemical reactions where the reactants form products, which can react again to form the original reactants. This is a common occurrence in biological systems where equilibrium is crucial.

A great example of this is the conversion of ATP to ADP and phosphate. While ATP hydrolyzation releases energy, the reverse reaction is essential for energy storage. Such equilibrium processes allow cells to efficiently manage and use energy.

Key Points:

• Reactions can proceed in both directions (forward and backward).
• Crucial for maintaining metabolic balance and energy flow.
• Equilibrium can shift based on concentration and environmental conditions.