Function of digestive enzymes - digestion of starch by saliva Flashcards
What is saliva ?
A mixture from different salivary glands: Parotid, submandibular, sublingual and buccal glands.
What does the parotid gland produce?
serous diluted saliva with a high volume of amylase.
What is alpha-amylase?
A hydrolytic enzyme which cleaves a-1,4-glycosidic bonds of starch molecules –> resulting in dextrin and maltose products.
What is the optimal pH for proper functioning of alpha-amylase?
Near pH 7,0
How can the amount of amylase in a sample be estimated?
By semiquantitative analysis–> detection of amylase activity by colour reactions.
What is saliva composed of?
99,4% water, organic substances (protein) and inorganic substances (mineral). Bacterial cells and white blood cells
Salivary amylase is also called?
Ptyalin
Function of Ptyalin?
hydrolyzes starch into maltose and dextrin.
Which animals does not have alpha-amylase in their saliva?
Horse, dog, cat
Where does polysaccharide digestion start?
In the mouth
How much of starch is digested in mouth?
5-10%
Where and how is the rest of the starch digested?
In small intestine by pancreatic amylase (40-50%)
What solution is used to detect starch?
Lugol’s solution –> iodine
How does iodine react with starch?
Iodine I2 changes into an iodine Ion –>I3- which forms a dark-blue complex with the starch molecule.
How can we see if the starch is degraded by a-amylase?
Lugol’s solution keeps its original dark-red colour. (Starch has been degraded to dextrine/maltose)
