Give an advantage of lactase and other digestive enzymes being located in the plasma membrane of cells lining the small intestine rather than being secreted by lumen of SI?

enzymes not lost with gut contents. More effective absorption of products by these enzymes

Absorption of galactose from SI is reduced if absorbing cells are treated with respiratory inhibitor. Suggest an explanation for this?

No ATP made. Therefore less galactose moves into cells by active transport.

Describe role of Rough ER in formation of chylomicrons?

For protein synthesis, chylomicrons are made of proteins

How do chylomicrons leave the epithelial cell?

Exocytosis because chylomicrons are very large.

Describe the role of enzymes of the digestive system in the complete breakdown of starch? [5 marks]

Salivary amylase hydrolyses starch into dissacharide maltose. Maltase breaks down maltose to glucose by hydrolysing glycosidic bonds

Describe the processes involved in the absorption of the products of starch digestion?

Glucose moves in with sodium via carrier protein, sodium removed from epithelial cell by active transport (sodium potassium pump) into blood.

Why does damage to the microvilli mean people will have a lower conc of aa in their blood

Less surface area, less absorption takes place. damage to channel proteins amino acids wont be absorbed as fast,

Why does higher conc of bile salts (smaller droplets of bile salts) cause a mixture of bile salts and lipase to become a lower PH

smaller droplets = larger SA = larger surface for lipase to act so more triglycerides digested. More fatty acids produced which lowers PH.

How are epithelial cells of SI adapted for the absorption of glucose? [6 marks]

Microvilli- Increase SA so diffusion can happen at a faster rate. Thin - Short diffusion pathway Many carrier proteins for active transport. Many mitochondria for ATP channel/ carrier proteins for facilitated diffusion Membrane bound dissacharidases

Describe the action of these membrane bound dipeptidases and explain their importance?

Break the peptide bonds and absorb amino acids.

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Explain why maltse catalyses only this reaction? (maltase > maltose hydrolysed)

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What organ produces maltase?

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Chapter 6 - Digestio

A level Biology Chapter 6 - Digestion+Absorption

Question	Answer
Explain why maltse catalyses only this reaction? (maltase > maltose hydrolysed)	specific tertiary structure of enzyme = specific active site shape complementary to specific substrate of maltose only. Every enzyme specific shape = only makes enzyme substrate complex with specific active site and substrate
What organ produces maltase?	Small Intestine
Name one other digestive enzyme located in the plasma membrane of cells lining the small intestine?	Dipeptidase
Give an advantage of lactase and other digestive enzymes being located in the plasma membrane of cells lining the small intestine rather than being secreted by lumen of SI?	enzymes not lost with gut contents. More effective absorption of products by these enzymes
Absorption of galactose from SI is reduced if absorbing cells are treated with respiratory inhibitor. Suggest an explanation for this?	No ATP made. Therefore less galactose moves into cells by active transport.
Describe role of Rough ER in formation of chylomicrons?	For protein synthesis, chylomicrons are made of proteins
How do chylomicrons leave the epithelial cell?	Exocytosis because chylomicrons are very large.
Describe the role of enzymes of the digestive system in the complete breakdown of starch? [5 marks]	Salivary amylase hydrolyses starch into dissacharide maltose. Maltase breaks down maltose to glucose by hydrolysing glycosidic bonds
Describe the processes involved in the absorption of the products of starch digestion?	Glucose moves in with sodium via carrier protein, sodium removed from epithelial cell by active transport (sodium potassium pump) into blood.
Why does damage to the microvilli mean people will have a lower conc of aa in their blood	Less surface area, less absorption takes place. damage to channel proteins amino acids wont be absorbed as fast,
Why does higher conc of bile salts (smaller droplets of bile salts) cause a mixture of bile salts and lipase to become a lower PH	smaller droplets = larger SA = larger surface for lipase to act so more triglycerides digested. More fatty acids produced which lowers PH.
How are epithelial cells of SI adapted for the absorption of glucose? [6 marks]	Microvilli- Increase SA so diffusion can happen at a faster rate. Thin - Short diffusion pathway Many carrier proteins for active transport. Many mitochondria for ATP channel/ carrier proteins for facilitated diffusion Membrane bound dissacharidases
Describe the action of these membrane bound dipeptidases and explain their importance?	Break the peptide bonds and absorb amino acids.

Created by: ksatti12

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