A2- DNA and anticancer drugs

Question 1

Why is DNA acidic?

Answer 1

phosphate groups have P-O-H which can donate H+ (and form P–O-)

Question 2

How many H bonds form between A and T?

Answer 2

2

Question 3

How many H bonds form between C and G?

Answer 3

3

Question 4

What do H bonds form between?

Answer 4

a H sandwiched between O or N

Question 5

What 2 groups react (and on which molecules) to form phosphodiester bonds?

Answer 5

OH on Phosphate and OH on sugar

Question 6

What sugar is found in DNA?

Answer 6

deoxyribose

Question 7

Draw cisplatin…

Answer 7

H3N Cl
Pt
H3N Cl

Question 8

How does cisplatin work?

Answer 8

• bonding to strands of DNA
  -distorting shape and prevents replication

Question 9

Where does cisplatin bond to DNA?

Answer 9

2 adjacent G bases

Question 10

How does cisplatin bond to DNA?

Answer 10

• N atom in G bases has lone pair that it donates to Pt
• forming a dative covalent bond

Question 11

What displaces the Cl in cisplatin?

Answer 11

H2O

Question 12

What displaces H2O ligands on cisplatin? What type of reaction is this?

Answer 12

N on Guanine bases
Ligand-substitution

Question 13

What process does cisplatin prevent?

Answer 13

DNA replication

Question 14

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

Answer 14

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

Question 15

What atoms donate electrons to cisplatin when it forms a cross-link between guanine bases/?

Answer 15

• N atoms on guanine
• donate electrons to Pt
• replace Cl ligands