Digestion And Haemoglobin Flashcards
Define digestion
- physical and chemical breakdown of large insoluble molecules into small soluble molecules
How is starch digested ?
- hydrolyse salivary amylase first into maltose = goes into stomach where stomach acid is too acidic which denatures enzyme to prevent future hydrolysis
- pancreatic juice release to duodenum that has pancreatic amylase continue break down starch into maltose
- in ileum, walls pushes maltose down then being broken down by maltase ( a membrane bound disaccharides produce by ileum ) into monomers of alpha glucoses, involve hydrolysis of glycosidic bond
How is lipids digested in small intestines ?
- bile salts released from gall bladder into liver, emulsify lipids into smaller droplets of lipids = provide large SA for hydrolysis of lipase enzymes
- lipase complete final hydrolysis of ester bond into monoglycerides and FA, ready to leave the cell
How is protein digested ? (4)
- involves hydrolysis of peptide bonds of polypeptide chains
- endopeptidase hydrolyse peptide bonds of central region in the chain = produce series of peptide molecules
- exopeptidase hydrolyse peptide bonds at the end of polypeptide chain = produce dipeptides and single amino acids
- membrane bound dipeptidase hydrolyse dipeptide into separate amino acids
How is monomers sugars absorbed after digestion of starch ?
- glucose absorbed by A.T with Na+ ions of carrier proteins via co transport
-galactose absorb using carrrier proteins - fructose absorb through facilitated diffusion of channel proteins
How is amino acid absorbed after digestion ?
- by co transport
- Na+ ions active transport out of ileum epithelial cell to create conc. grad.
Then sodium diffuses from lumen of ileum into epithelial cells by carrier proteins, carrying amino acids with it by co transport
How is lipids absorbed after digestion ?
micelles can release monoglycerides and fatty acids
- then enter epithelial cell of ileum walls by diffusion
- triglycerides are reform again in S.E.R and Golgi packaged cholesterol and lipid protein into chylomicrons
- then released by exocytosis to lymphatic vessel called lacteal to be transported into blood stream back into circulatory system
Explain how aerobic respiration in cells leads to a change in ph of blood plasma ? (2)
- CO2 is produced and forms carbonic acid
- H+ ions released to make plasma more acidic
What is advantage of tissue cells with low affinity of Hb when ph of plasma decreases? (2)
- ph decrease because of high rate respiration = cells need more O2
- low affinity allows O2 to be unload easily
Explain advantage of animals living at high altitude have dissociation Curve to the left ? (2)
- high altitude has low p.p of O2
- means animals will have high affinity of Hb , allow sufficient O2 supply to cells
Explain advantage of more active species having dissociation curve to the right ? (2)
- they have greater rate of respiration = means ph of plasma decreases so low affinity of Hb
- so O2 is released more easily for supplying cells
How does myoglobin benefit us in muscles for sustained contraction ? (3)
- myoglobin has high affinity of Hb means oxygen can be stored
- O2 can be released when at low p.p of O2
- allow aerobic respiration to continue
E.g. describe the process in absorption and transport of digested lipids from ileum into lymph vessels (5)
M1 micelles contain bile salts and fatty acids
- micelles release fatty acids and monoglycerides to lining of ileum
- fatty acids absorbed by diffusion
- triglycerides reformed by ER and chylomicrons form
- exocytosis occurs to release chylomicrons to lacteal
Functions of Golgi in absorption of lipids (3)
- processes triglycerides
- combine triglycerides with proteins into chylomicrons
- release by exocytosis to cell membrane
Explain how does monosaccharides glucose absorb into felling lining of ileum by co transport of sodium ions (3)
- Na+ diffuse from cell epithelium to blood stream by active transport against concentration gradient
- maintain the conc grad fro sodium ions to diffuse from gut to cells while carrying glucose with it in co transport
- glucose enters blood by facilitated diffusion with sodium ions
Explain advantage of lipid droplets and micelles formation (3)
- droplets increase surface area for lipase to hydrolyse
- so faster hydrolysis of digestion
- micelles carry fatty acids to epithelial cell of ileum lining
What is the advantage of micelles forming after digestion of lipids ? (2)
M1 makes fatty acids more soluble in water = enable to carry FA to epithelial cell lining of ileum
M2 ensure a high conc of FA out inside the cell surface membrane = that can then diffuse out the membrane later
How to collect data to get a reliable mean ? (2)
1) random sample
2) large sample size
Describe 3 functions of bile salts (3)
1) emulsify lipids
2) increase SA for increased lipase activity
3) form micelles to be transported easily
