Digestion and Absorption Flashcards
Can large biological molecules cross cell membranes?
Large biological molecules in food are too big to cross cell membranes. This means they can’t be absorbed from the blood into the gut
What happens to large molecules during digestion?
During digestion, large molecules are broken down into smaller molecules, which can move across cell membranes. This means they are easily absorbed from the gut into the blood, to be transported around the body for use by the body cells
How can large biological molecules be broken down?
Through hydrolysis reactions - hydrolysis reactions break bonds by adding water
During hydrolysis what are carbohydrates, fats and proteins broken down into?
Carbohydrates are broken down into disaccharides, then monosaccharides. Fats are broken down into fatty acids and monoglycerides. Proteins are broken down into amino acids
Where are digestive enzymes produced?
Digestive enzymes are produced by specialised cells in the digestive systems of mammals
What are carbohydrates broken down by?
Carbohydrates are broken down by amylase and membrane-bound disaccharides
What is amylase?
Amylase is a digestive enzyme that catalyses the conversion of starch (a polysaccharide) into the smaller sugar maltose (a disaccharide). This involves the hydrolysis of the glycosidic bonds in starch
Where is amylase produced?
Amylase is produced in the salivary glands (which release amylase into the mouth) and also by the pancreas (which releases amylase into the small intestine)
What are membrane-bound disaccharides?
Membrane-bound disaccharides are enzymes that are attached to the cell membranes of epithelial cells lining the ileum
What do membrane-bound disaccharides do?
They help to break down disaccharides into monosaccharides. This involves the hydrolysis of glycosidic bonds
How can monosaccharides be transported across cell membranes?
Monosaccharides can be transported across cell membranes of the ileum epithelial cells via specific transporter proteins
What are lipids broken down by?
Lipase with the help of bile salts
What do lipase enzymes do?
Lipase enzymes catalyse the breakdown of lipids into monoglycerides and fatty acids. This involves the hydrolysis of the ester bonds in lipids
Where are lipases made and where do they work?
Lipase are made in the pancreas. They work in the small intestine
What do bile salts do?
Bile salts are produced in the liver and emulsify lipids - this means they cause the lipids to form small droplets