Select The True Statement About Dehydration Synthesis Or Hydrolysis

Dehydration synthesis and hydrolysis are fundamental biochemical processes that play crucial roles in building and breaking down macromolecules within living organisms. Understanding the differences between these two processes is essential for comprehending how cells construct complex molecules and extract energy from them.

Understanding Dehydration Synthesis

Dehydration synthesis, also known as condensation, is the process by which monomers combine to form polymers. In this process, a water molecule (H2O) is removed. Specifically, a hydroxyl group (-OH) is removed from one monomer and a hydrogen atom (-H) is removed from the other, allowing the two monomers to form a covalent bond.

The Mechanism of Dehydration Synthesis

1. Monomer Alignment: The monomers align in such a way that the reactive parts of each monomer are positioned close together. This proximity is often facilitated by enzymes, which act as catalysts to speed up the reaction.
2. Water Removal: A hydroxyl group (-OH) from one monomer and a hydrogen atom (-H) from the adjacent monomer are removed. These combine to form a water molecule (H2O).
3. Bond Formation: As the water molecule is removed, a covalent bond forms between the two monomers, creating a dimer. This process can be repeated multiple times to add more monomers and create a polymer.

Examples of Dehydration Synthesis

• Protein Synthesis: Amino acids are linked together to form polypeptide chains. The carboxyl group (-COOH) of one amino acid reacts with the amino group (-NH2) of another, releasing a water molecule and forming a peptide bond.
• Carbohydrate Formation: Monosaccharides, such as glucose, combine to form disaccharides (like sucrose) or polysaccharides (like starch and cellulose). For example, two glucose molecules can combine to form maltose, with the release of a water molecule.
• Nucleic Acid Synthesis: Nucleotides are joined to form DNA and RNA strands. The phosphate group of one nucleotide bonds to the sugar molecule of another, releasing water and creating a phosphodiester bond.
• Lipid Synthesis: Fatty acids combine with glycerol to form triglycerides (fats and oils). The carboxyl group of a fatty acid reacts with a hydroxyl group of glycerol, releasing water and forming an ester bond.

Significance of Dehydration Synthesis

• Building Complex Molecules: Dehydration synthesis is essential for creating the large, complex molecules necessary for life, including proteins, carbohydrates, nucleic acids, and lipids.
• Energy Storage: Polysaccharides like starch and glycogen are formed through dehydration synthesis, providing a means to store glucose for later energy use.
• Structural Support: Polymers such as cellulose (in plant cell walls) and chitin (in fungal cell walls and exoskeletons of arthropods) are synthesized via dehydration synthesis, providing structural integrity to cells and organisms.

Understanding Hydrolysis

Hydrolysis is the reverse of dehydration synthesis. It is the process by which polymers are broken down into monomers through the addition of a water molecule. The word "hydrolysis" literally means "water splitting," which accurately describes what happens during the reaction.

The Mechanism of Hydrolysis

1. Water Addition: A water molecule (H2O) is added to the polymer. The water molecule splits into a hydroxyl group (-OH) and a hydrogen atom (-H).
2. Bond Breaking: The covalent bond between two monomers is broken. The hydroxyl group (-OH) attaches to one monomer, and the hydrogen atom (-H) attaches to the other, separating the monomers.
3. Monomer Release: The monomers are released as individual units. These monomers can then be used for energy or as building blocks for new molecules.

Examples of Hydrolysis

• Digestion of Proteins: During digestion, proteins are broken down into amino acids. Peptide bonds are hydrolyzed, with water being added to break the bond between adjacent amino acids.
• Breakdown of Carbohydrates: Polysaccharides like starch are hydrolyzed into glucose molecules. Glycosidic bonds are broken by the addition of water, releasing glucose for energy.
• Nucleic Acid Degradation: DNA and RNA strands are hydrolyzed into nucleotides. Phosphodiester bonds are broken with the addition of water, releasing nucleotides that can be reused or excreted.
• Lipid Breakdown: Triglycerides are hydrolyzed into glycerol and fatty acids. Ester bonds are broken by the addition of water, releasing these components for energy or other metabolic processes.

Significance of Hydrolysis

• Digestion and Nutrient Absorption: Hydrolysis is crucial for breaking down complex food molecules into smaller, absorbable units during digestion.
• Energy Release: Hydrolysis releases energy stored in the bonds of polymers, providing the cell with the energy needed for various metabolic processes.
• Recycling of Monomers: Hydrolysis allows cells to break down and recycle polymers into their constituent monomers, which can then be used to build new molecules.

Key Differences Between Dehydration Synthesis and Hydrolysis

To summarize, the main differences between dehydration synthesis and hydrolysis are:

• Process:
  • Dehydration Synthesis: Builds polymers by removing water.
  • Hydrolysis: Breaks down polymers by adding water.
• Water Involvement:
  • Dehydration Synthesis: Water is a product.
  • Hydrolysis: Water is a reactant.
• Energy:
  • Dehydration Synthesis: Requires energy (endergonic).
  • Hydrolysis: Releases energy (exergonic).
• Bond Formation/Breakage:
  • Dehydration Synthesis: Forms covalent bonds.
  • Hydrolysis: Breaks covalent bonds.

True Statements About Dehydration Synthesis and Hydrolysis

Given the explanations above, let's evaluate some possible statements to identify the true ones:

1. Dehydration synthesis requires the input of energy to form bonds.
   • True. Dehydration synthesis is an endergonic process, meaning it requires energy to create the covalent bonds that link monomers together.
2. Hydrolysis releases energy as polymers are broken down into monomers.
   • True. Hydrolysis is an exergonic process, releasing energy as the bonds between monomers are broken.
3. Dehydration synthesis involves the addition of a water molecule to break bonds.
   • False. Dehydration synthesis involves the removal of a water molecule to form bonds.
4. Hydrolysis involves the removal of a water molecule to form bonds.
   • False. Hydrolysis involves the addition of a water molecule to break bonds.
5. Dehydration synthesis is used to digest large food molecules into smaller, absorbable units.
   • False. Hydrolysis is used to digest large food molecules into smaller, absorbable units. Dehydration synthesis does the opposite by building large molecules.
6. Hydrolysis is used to build proteins from amino acids.
   • False. Dehydration synthesis is used to build proteins from amino acids. Hydrolysis breaks proteins down into amino acids.
7. In dehydration synthesis, a water molecule is formed as a byproduct.
   • True. During dehydration synthesis, a hydroxyl group (-OH) from one monomer and a hydrogen atom (-H) from another combine to form a water molecule (H2O).
8. In hydrolysis, a water molecule is split to break a bond between monomers.
   • True. In hydrolysis, a water molecule is added, splitting into -OH and -H, which attach to the separated monomers.
9. Dehydration synthesis is also known as condensation.
   • True. Dehydration synthesis is often referred to as condensation because water is removed during the process.
10. Hydrolysis is also known as polymerization.
    • False. Polymerization refers to the process of forming polymers, which is achieved through dehydration synthesis, not hydrolysis.

Further Elaboration on the Biochemical Significance

Role in Cellular Metabolism

Both dehydration synthesis and hydrolysis are integral to cellular metabolism. Metabolism encompasses all the chemical reactions that occur within a cell to maintain life. These reactions can be broadly classified into two categories:

• Anabolism: These are reactions that build complex molecules from simpler ones, requiring energy. Dehydration synthesis is a key anabolic process.
• Catabolism: These are reactions that break down complex molecules into simpler ones, releasing energy. Hydrolysis is a key catabolic process.

Enzyme Involvement

Enzymes play a critical role in both dehydration synthesis and hydrolysis. Enzymes are biological catalysts that speed up chemical reactions without being consumed in the process. They do this by lowering the activation energy of the reaction, making it easier for the reaction to occur.

• Enzymes in Dehydration Synthesis: Enzymes facilitate the alignment of monomers, the removal of water, and the formation of covalent bonds. Examples include enzymes involved in protein synthesis (e.g., ribosomes) and carbohydrate synthesis (e.g., glycogen synthase).
• Enzymes in Hydrolysis: Enzymes facilitate the addition of water and the breaking of covalent bonds. Examples include digestive enzymes like amylase (breaks down starch), protease (breaks down proteins), and lipase (breaks down fats).

Regulation of Dehydration Synthesis and Hydrolysis

The balance between dehydration synthesis and hydrolysis is tightly regulated within cells to maintain homeostasis. This regulation involves various factors, including:

• Enzyme Activity: The activity of enzymes involved in these processes can be regulated by various factors, such as pH, temperature, and the presence of inhibitors or activators.
• Substrate Availability: The availability of monomers and polymers influences the rates of dehydration synthesis and hydrolysis, respectively.
• Hormonal Control: Hormones can influence metabolic pathways and thus affect the balance between anabolism and catabolism. For example, insulin promotes anabolic processes, while cortisol promotes catabolic processes.

Examples in Biological Systems

Proteins

• Dehydration Synthesis: Amino acids are joined together by peptide bonds to form polypeptide chains. This process occurs in ribosomes during protein synthesis, where tRNA molecules bring specific amino acids to the ribosome based on the mRNA sequence.
• Hydrolysis: Polypeptide chains are broken down into individual amino acids during digestion or protein turnover. Proteases, such as pepsin, trypsin, and chymotrypsin, catalyze the hydrolysis of peptide bonds.

Carbohydrates

• Dehydration Synthesis: Monosaccharides, such as glucose, are linked together to form disaccharides (e.g., sucrose, lactose) and polysaccharides (e.g., starch, glycogen, cellulose). Glycogen synthase, for example, is an enzyme that catalyzes the synthesis of glycogen from glucose monomers.
• Hydrolysis: Polysaccharides are broken down into monosaccharides during digestion. Amylase, secreted by the salivary glands and pancreas, catalyzes the hydrolysis of starch into glucose molecules.

Nucleic Acids

• Dehydration Synthesis: Nucleotides are joined together by phosphodiester bonds to form DNA and RNA strands. DNA polymerase and RNA polymerase are enzymes that catalyze the synthesis of nucleic acids during replication and transcription, respectively.
• Hydrolysis: DNA and RNA strands are broken down into nucleotides during DNA repair or RNA degradation. Nucleases, such as DNases and RNases, catalyze the hydrolysis of phosphodiester bonds.

Lipids

• Dehydration Synthesis: Fatty acids are combined with glycerol to form triglycerides (fats and oils). This process occurs in the endoplasmic reticulum of cells.
• Hydrolysis: Triglycerides are broken down into glycerol and fatty acids during digestion or lipolysis. Lipases, such as pancreatic lipase, catalyze the hydrolysis of ester bonds.

Practical Applications and Relevance

Understanding dehydration synthesis and hydrolysis has several practical applications and is relevant in various fields:

• Medicine: Understanding these processes is crucial for understanding metabolic disorders, enzyme deficiencies, and the effects of drugs on biochemical pathways.
• Nutrition: Knowledge of how food molecules are broken down and synthesized is essential for understanding nutrition and designing healthy diets.
• Biotechnology: These processes are used in biotechnology for the synthesis of various biomolecules, such as recombinant proteins and synthetic polymers.
• Agriculture: Understanding carbohydrate synthesis in plants is important for improving crop yields and developing biofuels.

Conclusion

Dehydration synthesis and hydrolysis are fundamental biochemical processes that are essential for life. Dehydration synthesis builds complex molecules by removing water, while hydrolysis breaks down complex molecules by adding water. These processes are involved in the synthesis and breakdown of proteins, carbohydrates, nucleic acids, and lipids. Understanding the mechanisms, significance, and regulation of dehydration synthesis and hydrolysis is crucial for comprehending cellular metabolism, enzyme function, and various biological processes. Selecting the true statement about these processes requires a clear understanding of their opposing roles and the involvement of water, energy, and enzymes.