Carbs, Proteins, Lipid And Enzyme Questions Flashcards
Explain why phospholipids can form a bilayer but triglycerides can’t? (3)
- phospholipids have head which is a phosphate group that attracts to water
- phospholipid two fatty acid tails are hydrophobic and repel water
- triglyceride is only hydrophobic as has no phosphate group
GOS are polymers of galactose.
Explain why GOS are described as polysaccharides. (2)
-galactose is a monosaccharide
- GOS is made up of many galactose molecules bonded together by glycoside bonds in a condensation reaction
Explain why amylase, produced in the human digestive system, does not digest GOS. (2)
- amylase is an enzyme so its active site is only complementary to starch
- due to tertiary structure
Prebiotics are food used to promote good health in humans. Prebiotics simulate the growth of ‘healthy’ bacterial populations in the human digestive system.
The bacteria in these ‘healthy’ populations produce enzymes that hydrolyse GOS.
Suggest how GOS can work as a prebiotic. (3)
- provides galactose
- bacteria uses galactose for respiration
- bacteria use galactose for binary fission
When bread becomes stale, the structure of some of the starch is changed. This changes starch is called ‘retrograded starch’.
Scientists have suggested retrograded startch is a competitive inhibitor of amylase in the small intestine.
Assuming the scientists are correct, suggest how eating stale bread could help reduce weight gain. (3)
- retrograded starch molecules will bind to amylase active site and inhibit starch molecules from it, this reduces rate of reaction of hydrolysis of starch reducing the amount of maltose formed
- so glucose isn’t absorbed by body and so can’t gain weight
Describe how monomers join to form the primary structure of a protein. (3)
- two amino acid monomers are bonded together by peptide bonds in a condensation reaction forming a dipeptide
- many of these form making a polypeptide chain
- this is a specific sequence of amino acids
