digestion & absorption Flashcards
1
Q
starch digestion
A
- amylase hydrolyses glucosidic bonds in starch —> maltose
- maltase hydrolyses glycosidic bonds in maltose —> glucose
(glucose small enough to diffuse across gut wall)
2
Q
where is amylase found?
A
- amylase found in saliva & pancreas
- ileum contains membrane-bound disaccharides
3
Q
co-transport of glucose/amino acids
A
- Na+ ions actively transported from ileum cell to blood
- forms Na+ conc. gradient outside cell for Na+
- Na+ ions move into ileum via facilitated diffusion, co-transporting glucose/amino acids with it
4
Q
lipid absorption
A
lipase hydrolyses ester bonds in lipids —> fatty acids & glycerol
5
Q
where are lipase enzymes found?
A
- lipase found in pancreas
- liver makes bile salts
6
Q
advantages of lipid droplet & micelle formation
A
- droplets increase SA for absorption
- so faster hydrolysis of lipids
- micelles carry fatty acids to cell
- micelles contain bile salts —> makes fatty acids more soluble in water by emulsification
- fatty acids absorbed by diffusion
- triglycerides reformed in cell
7
Q
role of golgi apparatus
A
- modifies triglycerides
- combines triglycerides with proteins
- forms vesicles for exocytosis
8
Q
test for lipids
A
add water, then ethanol & shake —> white, milky emulsion
9
Q
test for proteins
A
add biurets reagent —> colour change to purple
10
Q
digestion =
A
hydrolysis of larger insoluble substances to smaller soluble ones
11
Q
absorption =
A
taking up of substances by a cell/tissue
12
Q
protein digestion =
A
- endopeptidases hydrolyse internal peptide bonds within polypeptides (more ends increases SA for exopeptides)
- exopeptidases hydrolyse peptide bonds at ends of polypeptides
*dipeptidases hydrolose peptide bonds in dipeptides —> amino acids
13
Q
where are peptidases found?
A
- peptidases found in the pancreas & stomach
- dipeptides work in small intestines
14
Q
features of specialised cells for absorption
A
- microvilli & folded membrane —> large SA for absorption
- large no. of mitochondria—> produces more ATP for active transport
- large no. of carrier proteins —> more active transport
15
Q
process of carbohydrate digestion in human digestive system
A
- amylase in saliva hydrolyses glycosidic bonds in starch into maltose
- maltase hydrolyses glycosidic bonds in maltose into glucose
- glucose small enough to diffuse across gut wall
