1. Digestion Flashcards
What is the problem with large biological molecules ?
Eg starch/ proteins
Too big t cross cell membrane.
Can’t be absorbed from the gut into blood
What happens to these large molecules ?
Broken down into smaller molecules (glucose/ amino acids) which are capable of moving across membranes.
They can easily absorb into gut in blood to be transported around body for use in body cells
HOW are these large molecules broken down ?
As they’re polymers they can be broken down into smaller molecules ( monomers) using hydrolysis reaction.
Hydrolysis of carbohydrates
Disaccharides and monosaccharides
Hydrolysis of fats
Fatty acids and monoglycetides
Hydrolysis of proteins
Amino acids
Function of digestive enzymes
Used to break down biological molecules in food.
Produced by specialised cells in digestive system.
Released in gut to mix with food. Thank
Why are digestive enzymes significant?
Different enzymes needed to catalyse breakdown of different food molecules
Function of amylase
Catalyses breakdown of starch.
It hydrolysis the glycosidic bonds in starch to produce maltose (disaccharide)
Enzyme > polysaccharide > disaccharide
Amylase
Amylase > starch > maltose
What is starch ?
Mixture of 2 polysaccharide chains
Each long chains of alpha glucose molecules
Where is amylase produced
Salivary glands
Released into mouth
Pancreas
Released into small intestine
What are membrane bound disaccharidases?
Enzymes
Attached to cell membrane of epithelial cells linking ileum
Help breakdown disaccharides into monosaccharides
This involves hydrolysis of glycosidic bonds
Sucrase
Membrane bound disaccharidase
Catalyses breakdown of sucrose into the monosaccharides glucose fructose
Maltase
Membrane bound disaccharidase
Catalyses breakdown of maltose into monosaccharides glucose and glucose
Lactase
Membrane bound disaccharidase
Catalyses breakdown of lactose into monosaccharides glucose and galactose
How to the monosaccharides transport across epithelial cell membrane ?
Via specific transporter proteins
What bonds to carbohydrates break ?
Glycosidic
Function of lipase enzymes
Catalyse breakdown of lipids into fatty acids and monoglycerides
Hydrolysis of water bond in lipids
Where are lipases produced?
Pancreas
Released into small intestine where they act.
Structure of monoglycetide molecule
Glycerol molecule
1 fatty acid attached
Where are bile salts produced ?
Liver
Function of bile salts
They emulsify lipids
Cause the lipids to form small droplets.
Several small droplets have a bigger surface area than a single large droplet (same volume)
This greatly increases surface area of lipid for lipase to work on
What bonds are hydrolysed in breakdown of lipids?
Ester
Once the lipid has been broken down by the lipase, monoglycerides and fatty acids stick with the bile salts, what structures form ?
Tiny structures
Micelles
These help with products of lipid digestion to be absorbed
Peptidases are also called
Proteases
What are proteins broken down into ?
Combination of different peptidases.
Endopeptidases
Exopeptidases
Catalyse hydrolysis of proteins into amino acids breaking the peptide bonds between amino acid
Function of endopeptidases
Hydrolysis peptide bonds within protein
How to remember what endopeptidases do
enDopeptidases
break bonds insiDe the proteins
Example of endopeptidases
Pepsin
Released in stomach
Works in acidic conditions - hydrochloric acid
Function of exopeptidases
Hydrolysise peptide bonds at the end of protein molecules
Remove single amino acids
What are dipeptidases?
Exopeptidases that work specially on dipeptides
Separate 2 amino acids that make up the dipeptide by hydrolysing peptide bonds.
Located on cell surface membrane of epithelial cells in small intestine
