O- Enzymes + DNA

Question 1

How does a substrate react with an enzyme?

Answer 1

• bonds temporarily by IMF
• which promote movement of e- within substrate
• ↓ Ea

Question 2

What is the use of computer modelling in medicine?

Answer 2

• predict shapes of proteins (b4 synth)
• predicts properties
• design drugs

Question 3

Which end of cisplatin binds to DNA?

Answer 3

Cl

Question 4

How does cisplatin work?

Answer 4

• binds to N on 2 adj. guanine bases on DNA
• distorts shape –> prevents replication
• lone pairs on N form dative covalent bonds w/ platinum (Pt)
• Cl- displaced by H2O ligands
• H2O displaced by N on guanine (better ligand)
• ligand substitution

Question 5

How many H bonds formed between C&G and A&T?

Answer 5

A-T = 2
C-G = 3

Question 6

Explain the origin of H bonds in an alpha helix. (4)

Answer 6

• both N & O are electronegative
• C=O & N-H are polar bonds
• lone pair on O attracted to δ+ H
• H bond forms

Question 7

After cisplatin enters a cell, one of the chloride ligands is replaced by a water molecule to form a complex ion, B.
Give the eqaution for this reaction. (2)

Answer 7

[Pt(NH3)2Cl2] + H2O –> [Pt(NH3)2Cl(H2O)]+ + Cl-