Digestion and enzymes Flashcards
Define digestion
The breakdown of large insoluble food molecules into small soluble food molecules by chemical and physical means
State an enzyme found in saliva
Amylase
State two examples of physical digestion
Teeth and churning of food in the stomach
State the enzyme found in the stomach
Pepsin (a protease which breaks down protein)
State some examples of enzymes found in the first part of the small intestine.
Pancreatic Amylase (secreted from the pancreas)
Protease (secreted from the pancreas)
Lipase (secreted from the pancreas)
Maltase (secreted by the small intestine)
Define enzyme
Protein biological catalayst that speeds up chemical reactions by lowering the activation energy.
Describe the active site of an enzyme
Specific and complementary in terms of shape and charge to the substrate. This means that the substrate can attach and enzyme-substrate complexes can form.
Explain why the rate of reaction is low for an enzyme at 5 degrees (very below optimum).
Because there is less kinetic energy the enzyme is inactive
Then there will be fewer successful collisions between enzyme and its subtrate molecules, leading to fewer enzyme-substrate complexes forming;
Therefore, the rate of reaction is slower, producing fewer products.
Explain why the rate of reaction is highest for an enzyme at its optimum temperature.
Because the enzyme is at its optimum temperature;
Then enzyme activity will be highest as there will be the greatest number of successful collisions between enzymes and substrates leading to the greatest number of enzyme-substrate complexes forming;
Therefore, the rate of reaction is fastest, producing the greatest amount of products.
Explain why the rate of reaction is lowest for an enzyme way above it’s optimum.
Because there is too much kinetic energy the enzyme becomes denatured
then the 3D structure of the active site of enzyme has changed and is no longer specific and complementary in terms of shape and charge to its substrate, so fewer enzyme-substrate complexes can form
Therefore, the rate of reaction is lowest, producing the least amount of products.
Define absorption
the movement of digested food molecules into the blood or lymph.
Define assimilation
the movement of digested food molecules into the cells of the body where they are used or become part of the cell.
Describe the function of the mouth in the digestive system.
Digestion. This means that the teeth physically break down food and saliva contains an enzyme, amylase, which chemically breaks down starch.
Give the function of the oesophagus in the digestive system
An organ which moves food from the mouth to the stomach by muscle contraction called peristalsis.
Give the function of the stomach in the digestive system
A muscular bag organ which churns food physically as well as chemically breaks down proteins with pepsin.
