Enzymes And Digestion Flashcards
What is the human digestive system made up of?
A long muscular tube and glands.
What do the glands produce?
They produce enzymes.
What do the enzymes do?
They hydrolyse large molecules into smaller ones ready for absorption.
What is the digestive system?
This is an exchange surface through which food substances are absorbed.
What does the oesophagus do?
This carries food from the mouth to the stomach.
What is the stomach?
A muscular sac with an inner layer that produces enzymes.
What is the role of the stomach?
To store and digest food, especially proteins.
What does the stomach have in order to digest protein?
Glands that produce enzymes that produce proteins.
What is the ileum?
This is a long, muscular tube .
How is food further digested by the ileum?
By the enzymes that are produced in its walls and by glands that pour their secretions into it.
What gives the ileum a large surface area?
The villi.
What can be found on the villi?
Tiny projections known as microvilli.
What is the purpose of the villi?
To absorb the products of digestion into the blood stream.
What does the large intestine absorb?
Water
What is most of the absorbed water secreted from?
From the secretions of many digested glands.
What does the rectum store?
Faeces
What is egestion?
This is where the faeces are removes via the anus.
Where are the salivary glands situated?
Near the mouth
How do the salivary glands pass their secretions to the mouth?
Via a duct
What do the salivary gland secretions contain?
Amylase
What does amylase do?
It hydrolyses starch to maltose.
What is the pancreas?
A large gland.
Where is the pancreas situated?
Below the stomach.
What is the name of the secretion produced by the pancreas?
Pancreatic juice
What does pancreatic juice contain?
Proteases
Lipase
Amylase
What do proteases hydrolyse?
Proteins
What does lipase hydrolyse?
Lipids
What does amylase hydrolyse?
Starch
What are the two stages of digestion?
Physical breakdown
Chemical digestion
What does chemical digestion hydrolyse?
Large, insoluble molecules into smaller, soluble ones.
What carries out hydrolysis?
Enzymes
How do all digestive enzymes function?
By hydrolysis
What is hydrolysis?
The splitting up of molecules by adding water to the chemical bonds that hold them together.
True or false: only one enzyme is needed to hydrolyse a large molecule?
This is false as enzymes are specific so more than one type of enzyme may be needed.
How do enzymes hydrolyse large molecules?
One enzyme hydrolyses the large molecule into smaller sections and then these sections are hydrolyses into smaller molecules by one or more additional enzymes.
What are the 3 types of digestive enzyme?
Carbohydrates
Lipases
Proteases
What do carbohydrates hydrolyse?
Carbohydrates to monosaccharides.
What do lipases hydrolyse?
Lipids into fatty acids and glycerol.
What do proteases hydrolyse?
Proteins to amino acids.
What happens first in carbohydrate digestion?
Amylase hydrolyses the alternate glycosidic bonds of starch to produce maltose.
What happens after the amylase breaks the glycosidic bonds?
The maltose is hydrolysed into alpha glucose.
What type of enzyme hydrolysis maltose to alpha glucose?
Disaccharidase
What is the name of the disaccharidase enzyme that hydrolyses maltose?
Maltose
What does saliva contain?
Salivary amylase and mineral salts.
What is the purpose of the mineral salts in the saliva?
To maintain the pH.
What denatures the amylase?
The stomach acid.
What happens when the food is passed into the small intestine?
It mixes with the secretion from the pancreas called pancreatic juice.
What does the pancreatic juice contain (in carbohydrate digestion)?
Pancreatic amylase
What does the lining of the ileum contain?
It contains maltase.
Why is maltase referred to as it membrane-bound disaccharidase?
This is because maltase is not released into the lumen of the ileum but it is part of the cell-surface membranes of the epithelial cells that line the ileum.
What does sucrase hydrolyse?
The single glycosidic bond in the sucrose molecule. This hydrolysis produces two monosaccharides glucose and fructose.
What does lactase hydrolyse?
The single glycosidic bond in the lactose molecule. This hydrolysis produces two monosaccharides glucose and galactose.
What type of enzymes hydrolyse lipids?
Lipases
Where are lipases produced?
In the pancreas.
What do lipases hydrolyse?
The ester bond that is found in triglycerides. This forms fatty acids and monoglycerides.
What is a monoglyceride?
A glycerol molecule with a single fatty acid molecules attached.
What are lipids first split up into?
They are split up into tiny droplets called micelles by bile salts.
Where are bile salts produced?
In the liver.
What is the process of breaking down lipids into micelles known as?
Emulsification
What does emulsification do?
This increases the surface area of the lipids say that the action of lipases it speeded up.
What are proteins hydrolysed by?
Peptidases
Tell the three types of peptidases?
Endopeptidase
Exopeptidase
Dipeptidase
What do you endopeptidases hydrolyse?
Peptide bonds between amino acid is in the central region of a protein molecule forming a series of peptide molecules.
What do you exopeptidase is hydrolysed?
They hydrolyse the peptide bonds on the terminal amino acids of the peptide molecules formed by endopeptidases in this way they are progressively released as dipeptides and single amino acids.
What do dipeptidases hydrolyse?
They hydrolyse the bond between the two amino acids of the dipeptide. Dipeptidase is membrane-bound, being part of the cell-surface membrane of the epithelial cells lining the ileum.
