Question
Fig. 5.1 shows a diagram of the molecular structures of tristearin (a triglyceride) and phosphatidylcholine (a phospholipid).
(a) Table 5.1 shows a structural difference between the two molecules shown in Fig. 5.1.
Complete Table 5.1 with two further structural differences other than in numbers of different types of atoms.[2]
(b) Cells in the pancreas secrete enzymes, such as amylase and trypsin, into a duct.
The enzymes are packaged in vesicles so that they can be exported from these cells as shown in Fig. 5.2.
With reference to Fig. 5.2, explain how enzymes that are secreted by cells in the pancreas are packaged into vesicles and exported.[4]
(c) Water has many significant roles to play in cells and living organisms.
Complete Table 5.2 below by stating the property of water that allows each of the following to take place.[3]
[Total: 9]
Answer/Explanation
Ans:
5 (a)
(b) answer may be phrased in the context of amylase/ trypsin ignore anything before Golgi, e.g. shuttle vesicles from RER
1 vesicles, form from/ ‘pinch off’, Golgi (apparatus /body / complex) ;
2 vesicles moves, through cytoplasm/ to cell (surface) or plasma membrane ;
3 role of cytoskeleton/ microtubules in movement of vesicles ;
4 energy /ATP, is required (movement of vesicles / fusion with membrane) ;
5 vesicle fuses with/AW, cell (surface)/ plasma, membrane ;
I bind/ attach A join/ merge/ becomes part of
6 exocytosis / vesicle ‘opens up’ so that enzyme molecules are released ;
7 ref to fluid nature of, membranes / phospholipid bilayer, that makes this possible ;
(c)
