Download Cardiff International School Dhaka (CISD) Lost Class Make Up

Cardiff International School Dhaka (CISD)
Lost Class Make Up Assignment
Class: A2/A3
Subject: Chemistry
Date: 22nd (Sunday)-28th (Saturday) February 2015
Total Mark- 20
Instructions: All of your assignment must be done in A4 size paper. Mention your Name,
Class, Roll and Section clearly on the top sheet of your assignment.
Submission Deadline: Saturday 28th February 10.00 AM to the respective subject teacher.
The deadline is strict.
Name:.................................................................................................................................................
Class: .........................Roll: ........................ Sec: .................. Teacher: ......................................
Sunday-Saturday
22-28 February 2015
Lesson:
28.5 Factors affecting enzyme activity
Task:
Study –
i. Difference between competitive and non-competitive inhibitor
ii. Effect of temperature on enzyme activity
iii. Effect of pH on enzyme activity
iv. Chemical denaturation
v. Cofactors: prosthetic groups and coenzymes
Worksheet/Exercise:
Q1. (a) Describe three differences between a competitive inhibitor and a non-competitive
inhibitor.
[3]
(b) Thallium is a heavy metal.
i. Write an equation to show the reaction of thallium (I) ions, TI+, with the sulfhydryl group in
a cysteine residue.
[2]
ii. What type of inhibitors are thallium (I) ions? Explain.
[2]
Q 2. (a) Sketch a graph to show how the activity of an enzyme varies with temperature.
[3]
(b) Explain the shape of the graph in terms of kinetic theory and the effect of temperature on
the integrity of the enzyme’s structure.
[3]
(c) Sketch a graph to show how pH affects the activity of a neutral protease.
[3]
(d) Explain the shape of the graph in terms of changes taking place in the region of the
enzyme’s active site.
[4]
Text Book/Reference Book:
Chemistry Coursebook, Page No. 417 - 421, Chapter – 28
Answer Keys:
Q1.(a) For example: A competitive inhibitor has a similar shape and distribution of charge to
the normal substrate. On the other hand, a non-competitive inhibitor doesn’t have a similar
shape to the normal substrate.
(b) Heavy metals (Ag, Hg, TI), ions react with one or more sulfhydryl groups, replacing the
hydrogen atom with a metal ion.
Q2. (a) At temperatures between 0o C and about 40 o C the rate of enzyme activity increases
with temperature. Enzyme activity decreases markedly above 40 o C.
(b) As temperature increases the molecules move faster, a greater proportion of the molecules
collide etc.
(c) Extremes of pH denature enzymes by disrupting their tertiary structure. Most enzymes
are active over a narrow pH range.
(d) The activity of some enzymes depends on particular amino acid residues at the active site
being charged, or not being charged. In these cases, a shift of pH by even 1 unit change can
change the enzyme activity significantly.
Help Lines:
For any assistance, please contact
Chemistry Teacher:
Jobaida Akther, [email protected]
Principal Head of School: G.M.Nizam Uddin, +88-01622181818, [email protected]