Enzymes in digestion
Enzymes: Globular proteins that are biological catalysts which increase the rate of a reaction by lowering the activation energy
- Digestive enzymes are released into the gut from
glands and are used in catabolic reactions that break down large molecules
- Lowering the activation energy
high temperatures are not needed because it would cause damage to cells and proteins
- An enzyme allows for a reaction to occur
more quickly at body temperature
- Large food molecules must be digested before the nutrients can be absorbed
By digesting larger molecules the products are:
- Soluble
- Small
enough for absorption into blood and assimilation into tissues
Large molecules are unable to diffuse across cell membranes into the blood by:
- Digestion
- Absorption
One process of making large molecules smaller is chemical digestion
Proteins: Proteins - Amino acids done by Protease
Lipids: Trigylcerides - Glycerol and Fatty acids done by Lipase
Carbs: Mono/di/polysaccharides - Monosaccharides done by Carbohydrase example (Amylase)
Main enzymes in Human Digestion
Amylases break down carbohydrates
- Example:
- Salivary Amylase
- Substrate:
- Starch
- Product: Maltose
- Source: Salivary glands in mouth
- Optimum pH: 7 - 7.8
Proteases break down polypeptides
- Example:
- Pepsin
- Substrate: Polypeptides
- Product:
- Amino acids
- Source:
Stomach
- Optimum pH: 2
Lipases break down fats and lipids
- Example: Pancreatic
- lipase
- Substrate: Triglycerides
- Product:
- Fatty acids and glycerol
- Source: Pancreas delivered into
small intestine
- Optimum: 7.2 -7.5
Organs and digestive enzymes
Mouth: Amylase
- Amylase is secreted by the salivary glands starts to break down
starch into maltose
Stomach: Pepsin
- Pepsin is a Protase enzyme that works in an optimum pH of 2
- Hydrochloric acid kills bacteria and provides
acidic conditions
Pancreas: Lipase
- Pancreas secretes Pancreatic juice which has enzymes (carbohydrase, protase and lipase) which digest starch, proteins and lipids
- Alkaline to
neutralize stomach content
Enzymes
- Allow digestive processes to occur at body temperature and at the necessary speed to meed organisms survival requirements
- Specific for a given substrate this allows digestion of certain molecules
The Pancreas
Pancreatic juice has enzymes:
- Carbohydrase
- Endopeptidase
- Trypsin
- Protease
- Lipase
which digests starch, lipids and proteins
Alkaline to neutralize stomach content
The Pancreas also produces Insulin and Glucagon for Glucose Metabolism
Endopeptidase hydrolyses long polypeptides into smaller polypeptides. Other protein-digesting enzymes hydrolyze smaller polypeptides into amino acids
And that's the end! Yay!
References:
https://www.google.com/url?sa=i&url=https%3A%2F%2Fwww.macmillan.org.uk%2Fcancer-information-and-support%2Fpancreatic-cancer%2Fthe-pancreas&psig=AOvVaw07YVMNVWT2RfWBrbyvOAmb&ust=1625292937337000&source=images&cd=vfe&ved=0CAoQjRxqFwoTCLC5wZnew_ECFQAAAAAdAAAAABAQ
https://www.google.com/url?sa=i&url=https%3A%2F%2Fwww.pinterest.com%2Fpin%2F701294973219612257%2F&psig=AOvVaw1tt9jMPhJKWokjqD5hKgQn&ust=1625293092045000&source=images&cd=vfe&ved=0CAoQjRxqFwoTCKjqkOXew_ECFQAAAAAdAAAAABAN
Drafted by Venetia (Biology)