Question

1. people with heartburn often take antacids, medicines that lower the acidity of the stomach to make it less acidic. could this affect the digestion of food? how? be specific.
2. dna polymerase cannot break down protein. pepsin cannot make dna. explain why.

Explanation:

For question 10:

Stomach acid (HCl) serves two key digestive roles: it activates pepsinogen into pepsin, the enzyme that breaks down proteins, and it helps dissolve and denature proteins to make them accessible to enzymes. Antacids neutralize stomach acid, reducing its acidity. This lowers the activation of pepsinogen, decreasing pepsin levels and impairing protein breakdown. Additionally, less acidic conditions reduce protein denaturation, making it harder for digestive enzymes to act on proteins. Antacids may also slightly slow the breakdown of some other nutrients by reducing the acidic environment that aids in initial food breakdown, though the primary impact is on protein digestion.

For question 11:

Enzymes are highly specific biological catalysts, with their function dependent on their unique three-dimensional structure, particularly the active site. The active site of an enzyme matches the shape and chemical properties of its specific substrate. DNA polymerase has an active site shaped to bind DNA nucleotides and catalyze DNA synthesis, so it cannot interact with protein substrates to break them down. Pepsin has an active site specialized to bind and break down protein molecules, so it cannot recognize DNA nucleotides as substrates to catalyze DNA formation. This specificity arises from the enzyme's amino acid sequence and folding pattern.

Answer:

1. Yes, antacids can affect digestion, primarily by impairing protein breakdown:

• Stomach acid activates pepsinogen to pepsin (the main protein-digesting enzyme); reduced acidity lowers pepsin production, slowing protein breakdown.
• Stomach acid denatures proteins (unfolds their structure) to make them accessible to enzymes; less acidity reduces this denaturation, making proteins harder to digest.

1. This is due to enzyme specificity:

• Each enzyme has a unique active site that only binds its specific substrate.
• DNA polymerase's active site fits DNA nucleotides (for DNA synthesis), not proteins.
• Pepsin's active site fits protein molecules (for protein breakdown), not DNA nucleotides.