3.3.3.1 Proteins - Enzymes and Digestion Flashcards
The 2 stages of digestion in humans are…
Physical breakdown by teeth or stomach churning
Chemical digestion by enzymes
What is the function of the pancreas?
Releases pancreatic juice onto food, as it exits the stomach, which contains proteases, lipases and carbohydrases.
Give some examples of proteases involved in digestion
Endopeptidase
Exopeptidate
Dipeptidase
What is the function of teeth?
To physically bread down food and increase its surface area
Identify the part of the digestive system
Oesophagus
Identify the part of the digestive system
Gall Bladder
What is meant by chemical digestion?
When large food molecules are hydrolysed into smaller molecules by enzymes.
Give some examples of carbohydrases involved in digestion
Salivary Amylase
Pancreatic Amylase
Maltase
Sucrase
Lactase
Name the cell membrane-bound protease
Dipeptidase
Bile salts are produced by the…
liver
What is the function of maltase?
To break down maltose into 2 α-glucose molecules
What is the function of the stomach?
Produces proteases for protein digestion
Churns food to physically break it down
Identify the part of the digestive system
Rectum
What is the function of salivary amylase?
To hydrolyse starch into maltose
What is the function of lipase?
To hydrolyse the ester bonds in triglycerides to give fatty acids and monoglycerides
How does the body break down maltose?
The lining of the ileum has maltase enzymes bound to their membranes.
Identify the part of the digestive system
Pancreas
What is the function of exopeptidases?
To hydrolyse the peptide bonds at the ends of peptide molecules, which releases amino acids and dipeptides.
Name the 3 membrane-bound disaccharidases…
Maltase
Sucrase
Lactase
What is the function of dipeptidases?
To hydrolyse the peptide bonds between dipeptides.
They are membrane bound enzymes.
What is the function of the ileum (small intestine)?
Produces enzymes to digest food
Absorbs the products of digestion into the blood.
What is the function of the oesophagus?
To carry food from the mouth to the stomach
What is the function of the large intestine?
To absorb water
Identify the part of the digestive system
Salivary Glands
What is meant by egestion?
The removal of faeces via the anus
Identify the part of the digestive system
Ileum (small intestine)
Identify the part of the digestive system
Large Intestine
What is the function of bile salts?
To emulsify large lipid molecules into smaller lipid micelles. To increase the surface area that lipase can act on.
What is the function of lactase?
To hydrolyse the glycosidic bond in a lactose molecule to give glucose and galactose.
What is the function of pancreatic amylase?
To hydrolyse starch in the ileum that was not broken down in the mouth.
How does physical breakdown aid digestion?
Creates a larger surface area for enzymes to act on.
Makes food easier to ingest (swallow).
Starch is not digested when food enters the stomach. Why?
The salivary amylase enzymes are denatured by the hydrochloric acid in the stomach.
What is the function of endopeptidase?
To hydrolyse the central peptide bonds in a large protein molecule to give smaller peptide molecules.
Name the 3 categories of enzymes.
Carbohydrases
Proteases
Lipases
Which type of bond does amylase break?
α 1-4 glycosidic bonds
What is meant by hydrolysis?
When a water molecule is added to a molecule to break a chemical bond.
What is the function of sucrase?
To hydrolyse the glycosidic bond in a sucrose molecule to give glucose and fructose.
Identify the part of the digestive system
Anus
Which enzyme is produced by the salivary glands?
Salivary Amylase
Enzymes are secreted by…
glands
What is the function of the rectum?
The final section of the intestines which stores faeces
What is a monoglyceride?
A glycerol molecule with 1 fatty acid attached.
Name the 3 proteases (peptidases) that are involved in protein digestion.
Endopeptidase
Exopeptidase
Dipeptidase
Bile salts emulsify large lipid molecules into smaller lipid molecules called…
micelles
What is a membrane-bound disaccharidase?
An enzyme that is part of the epthelial cell surface membranes of the ileum. They break down disaccharides.
What is a gland?
An organ in the body that secretes substances such as enzymes or hormones.
Identify the part of the digestive system
Stomach
What is the function of the salivary glands?
They secrete the enzyme salivary amylase, which hydrolyses starch into maltose.
How is glucose absorbed by co transport in the GUT with Na ions?
- co transport
- Na ions actively transported from ileum cell to the blood
- maintains a diffusion gradient for Na to enter the ileum cell from the gut lumen (bringing glucose with it)
- glucose enters with Na
- glucose enter to blood by faciliated diffusion
exo and edopeptidases are required for protein hydrolysis - name another enzyme needed to complete protein hydrolysis
dipeptidases
what do endopeptidases do?
Endopeptidases hydrolyse internal (peptide bonds)
What do exopeptidases do?
Exopeptidases remove amino acids/hydrolyse (bonds) at end(s);
Why does the action of exo and endopeptidases result in more efficient hydrolysis?
endopeptidases create more ends or increase in surface area (for exopeptidases);
Describe the action of membrane dipeptidases
Hydrolyse peptide bond to release amino acids
(dipeptides cannot cross the cell membrane)
define digestion
HYDROLYSIS of LARGE insoluble molecules into SMALLER soluble molecules
