BIOLOGY I

TUTORIAL 2
BASIC MOLECULES OF CELLS II

Student’s Guide:
At university level, the tutor facilitates student learning without spoon-feeding. Therefore, you are expected to:

• Read your textbook, attempt the questions before the tutorial • You may enter the class and sign your attendance after showing your tutor that all tutorial questions have been completed; even if you don’t know how to do, write something - you’re not advised to leave answers blank in the finals. • Write answers on board if you wish to receive tutor feedback (no answer, no feedback) • Be independent: consult textbooks or dictionaries on your own first before asking the tutor • All questions are compulsory. 1 mark may reflect 1 answer point. (No half mark is awarded in the finals marks)

(Source: Final examination, Dec 2012)
Q1. (a) Amino acids are the building blocks of proteins. Figure 1.1 shows the dipeptide molecule.

[pic]
Figure 1.1

i) Briefly explain the formation of dipeptide from two amino acids. (3 marks)

ii) Name the molecular unit that could determine the structure of a protein. (1 mark)

(Source: Final examination, Apr 2012)
Q2 (a) Figure 2.1 shows a representation of a phospholipid molecule and Figure 2.2 shows the detailed structure of a fat molecule.
[pic] [pic]
Figure 2.1 Figure 2.2

(i) Based on Figure 2.1, name the parts of the molecule labeled as A, B and C. (3 marks)

(ii) Based on Figure 2.1 and 2.2, briefly describe the chemical structure of lipids that account for their insolubility in water. (1 mark)

(iii) During a practical session, Ms. Chan demonstrated to the students that when water and oil were added to a test tube,