Question

Name an enzyme that acts on each molecule. (a) Lactose (b) Protein (c) RNA

Short answer

(a) Lactase (b) Protease (c) Ribonuclease (RNase)

Step-by-step solution

Identify Enzyme for Lactose

Lactose, a disaccharide sugar, is broken down into its monosaccharide components by the enzyme lactase. The reaction occurs in the small intestine where lactase catalyzes the hydrolysis of lactose into glucose and galactose.

Identify Enzyme for Protein

Proteins are broken down by proteolytic enzymes called proteases or peptidases. These enzymes, such as trypsin, chymotrypsin, and pepsin, catalyze the hydrolysis of peptide bonds within proteins to form smaller peptides or amino acids.

Identify Enzyme for RNA

RNA molecules are degraded by enzymes known as ribonucleases (RNases). These enzymes cleave the phosphodiester bonds in RNA, resulting in the breakdown of RNA into smaller components or nucleotides.

Key concepts

Lactase

Lactase is an important enzyme that primarily works in the small intestine. Its main role is to facilitate the digestion of lactose, which is a sugar found in milk and other dairy products. Lactase does this by breaking down lactose into two simpler sugars: glucose and galactose.
The absence or deficiency of lactase in the digestive system can lead to lactose intolerance. In lactose intolerance, undigested lactose passes into the large intestine where it is fermented by bacteria. This fermentation can cause uncomfortable symptoms such as bloating, gas, and diarrhea.

• Lactase breaks lactose down into glucose and galactose.
• It is crucial for the digestion of dairy products.
• Lactose intolerance results from insufficient lactase production.

Understanding lactase and its function helps in managing dietary habits and recognizing symptoms related to lactose intolerance.

Proteases

Proteases are enzymes that play a critical role in the digestion of proteins. They are also known as proteinases or peptidases. These enzymes break down proteins into smaller peptides or even individual amino acids, a process essential for various bodily functions.
One can find proteases in different parts of the digestive system, including the stomach and small intestine. Some of the key proteases include:

• Trypsin and chymotrypsin - primarily active in the small intestine.
• Pepsin - mainly functions in the acidic environment of the stomach.

Beyond digestion, proteases have important roles in many physiological processes such as cell division, immune function, and blood clotting. These enzymes are integral to maintaining protein homeostasis in the body.

Ribonucleases

Ribonucleases, commonly referred to as RNases, are enzymes that specialize in the degradation of RNA molecules. They are crucial for various biological processes because they help regulate the levels of RNA inside cells.
By cleaving the phosphodiester bonds that connect the RNA nucleotides, ribonucleases break down RNA into smaller pieces or individual nucleotides. This process is vital for the normal turnover of RNA and for defending the cell against RNA viruses.

• RNases help maintain cellular RNA balance.
• They play a role in defending cells from RNA viruses.

The activity of ribonucleases is carefully regulated to ensure proper cellular function, highlighting their importance in the molecular machinery of life.