Enzymes in Digestion
What is the name of the enzyme in saliva that begins starch digestion?
Amylase
In which organ does most chemical digestion occur?
Small intestine
What is the building block of proteins?
Amino acids
What causes lactose intolerance?
Lack of the enzyme lactase
What is peristalsis?
Wave-like muscle contractions that move food through the digestive tract
This enzyme breaks proteins into peptones and is activated by HCl in the stomach.
Pepsin
What part of the small intestine receives enzymes from the pancreas?
Duodenum
Which macronutrient provides the quickest source of energy?
Carbohydrates
Name one hormone involved in digestion and its role.
Gastrin: stimulates release of gastric juices
What is the difference between physical and chemical digestion?
Physical: mechanical breakdown; Chemical: enzymatic breakdown of macromolecules
What are three factors that can affect enzyme activity?
pH, temperature, and substrate concentration
Where is bile stored, and where does it act?
Stored in the gall bladder; acts in the small intestine
What is the role of emulsification in fat digestion, and what substance helps with this?
Breaks fat into smaller droplets; bile
What is the function of the mucous lining in the stomach?
Protects stomach lining from acidic gastric juices
What are the four steps of digestion (in order)?
Ingestion, Digestion, Absorption, Egestion
What enzyme is released by the pancreas and breaks down triglycerides into fatty acids and glycerol?
Pancreatic lipase
Name the four parts of the digestive tract where protein digestion takes place in order.
Mouth (mechanical only), stomach, small intestine (duodenum and jejunum)
Where are amino acids and monosaccharides absorbed, and how?
In the small intestine through villi into the blood capillaries
Explain what causes jaundice and which organ is involved.
Liver dysfunction or bile duct blockage leading to bile buildup
What’s the difference between saturated and unsaturated fats?
Saturated: single bonds, solid at room temp; Unsaturated: double bonds, liquid at room temp
Explain the difference between competitive inhibition and feedback inhibition.
Competitive inhibition: inhibitor blocks the active site. Feedback inhibition: product of a reaction inhibits the enzyme through a regulatory site.
Explain the process of how bicarbonate ions help regulate pH in digestion.
Secretin triggers pancreas to release bicarbonate into the duodenum to neutralize stomach acid.
Name 2 enzymes involved in fat digestion and their function.
Pancreatic lipase (triglycerides → glycerol + fatty acids), Phospholipase (phospholipids → glycerol + fatty acids + phosphate)
What is PKU, and how does it relate to enzyme deficiency?
PKU is a condition where the enzyme phenylalanine hydroxylase is missing, leading to toxic buildup of phenylalanine
Describe the pathway of a steak (protein) through the digestive system from mouth to absorption.
Mouth → Esophagus → Stomach (pepsin) → Small intestine (trypsin, erepsin) → Absorption into villi