4.2.2.1 the human digestive system

• What do carbohydrates provide for the body?

  Fuel for body reactions
• What is the best-known example of a simple carbohydrate?

  Sugar (glucose)
• What larger carbohydrate molecules can glucose units form?

  Starch and cellulose
• What are complex carbohydrates made of?

  • Long chains of simple sugar units
  • Linked together to form larger molecules
• What forms do lipids take in the diet?

  Fats, oils, and phospholipids
• What two molecules make up lipids?

  Fatty acids and glycerol
• What are proteins used for in the body?

  Building cells and tissues
• How many different amino acids are there?

  Around 20 different amino acids
• What are enzymes classified as?

  Biological catalysts
• What is the significance of an enzyme's shape?

  The shape is vital for enzyme function
• What are enzymes made of?

  Large protein molecules
• What is an active site?

  It is where the substrate binds on the enzyme
• What is the visual representation of enzyme action often referred to?

  The lock and key mechanism
• What happens to the enzyme after it catalyzes a reaction?

  It remains unchanged and can be reused
• What types of metabolic reactions do enzymes catalyse?

  • Building large molecules from smaller ones
  • Changing one molecule into another
  • Breaking down large molecules into smaller ones
• What large molecules can be built from glucose?

  Starch, glycogen, and cellulose
• What is an example of changing one molecule into another?

  Changing glucose to fructose
• What happens during the breakdown of large molecules?

  They are converted into smaller molecules
• What happens to enzymes at high temperatures?

  Their protein structure is affected and denatured
• What occurs to the active site of an enzyme when it is denatured?

  The shape of the active site changes
• What is the consequence of an enzyme being denatured?

  It can no longer act as a catalyst
• At what temperature do most human enzymes work best?

  37°C
• What happens to enzymes when body temperature reaches about 41°C?

  They start to be denatured
• What is the potential outcome if enzymes are denatured due to high temperature?

  It can result in death
• How does pH affect enzyme action?

  It changes the shape of the enzyme
• How do digestive enzymes differ from other enzymes?

  They work outside your cells
• Why is it important for food to be broken into small pieces?

  To increase surface area for enzymes
• What is the pH level of the stomach?

  Low, acidic pH value
• What are enzymes that break down carbohydrates called?

  Carbohydrase
• What carbohydrate is commonly broken down by carbohydrase?

  Starch
• Where does starch digestion begin?

  In the mouth
• What enzyme catalyses the breakdown of starch?

  Amylase
• Where is amylase produced?

  In the salivary glands and pancreas
• Where does most starch digestion occur?

  In the small intestine
• What enzymes catalyse the breakdown of proteins?

  Protease enzymes
• What foods are broken down by proteases?

  Meat, fish, and cheese
• Where does protein breakdown occur?

  In the stomach and small intestine
• What are lipids broken down into?

  Fatty acids and glycerol
• What enzyme catalyses the breakdown of fats?

  Lipase
• Where are lipase enzymes produced?

  In the pancreas and small intestine