Chemistry In Medicine

Question 1

What causes Indigestion

Answer 1

Excess HCl in stomach

Question 2

Indigestion remedies

Answer 2

Antacids - neutralise excess HCl

Most Metal Hydroxides, Carbonates or Hydrogencarbonates

Question 3

How can Mg(OH)2 and CaCO3 percentage in a remedy be determined

Answer 3

Via back titration

Question 4

Indigestion equations

Answer 4

Question 5

Protective layer on skin surface

Answer 5

Acid Mantle
Made up of water and fatty acids prod from glands in skin

Also lactic acid and AA from sweat

pH 4-5

Question 6

How does acid mantle protect from bacteria

Answer 6

Blood is alkaline
If bacteria adapts to acidic surface to penetrate - will be less adapted to alkaline blood

Question 7

Desquamation

Answer 7

Self-cleaning mechanism by which skin cells are shed

Question 8

Changes in Skin pH

Answer 8

Age, Stress, Dust, Pollutants, Soap and Cleaning Prod, Hormonal Changes and Sun exposure

Most soap pH 8-11 - remove acid mantle and lipids from skin where dirt and unwanted bacteria trapped

Skin cleaning prod should ideally be slightly acidic - do not disrupt pH of acid mantle

Question 9

Warts

Answer 9

Caused by Human Papillomavirus

Cause excessive keratin in top layer of skin - hard protein gives wart tough texture

Removed with corrosive chemicals; salicylic acid, di/tri/chloroethanoic acid and formic acid

Chemicals destroy living tissue of wart and area around it - killing virus

Question 10

Chlorine Atom in Removal of Warts

Answer 10

Cl in Chloroethanoic acid is electronegative and draws e- towards it

Pulls e- towards O in O-H
Ce acid stronger than ethanoic acid

Effect greater with more Cl

Question 11

Alkyl groups in removal of warts

Answer 11

Push e- away from themselves and pushes e- in O-H towards H

Ethanoic weaker acid than methanoic

Question 12

Eye Diseases

Answer 12

Silver(I) ion, Ag+

Antibacterial prop, particularly against E. coli and Staph

Silver(I) Nitrate , AgNO3

Relatively inexpensive and used in treatment of conjunctivitis in newborn babies

Antibiotics - Erythromycin a d Tetracycline now more commonly used

Question 13

Cisplatin

Answer 13

Anticancer drug

Z form of [Pt(NH3)2Cl2]

Square planar shape

No overall charge

Reacts w/ water and one chloro ligand sub for water ligand

Question 14

2 Ways [Pt(NH3)2Cl(H2O)]+ acts as anticancer drug

Answer 14

1. N atom in guanine (DNA base) bonds to Pt, displacing water ligand
2. H atom on one of NH3 ligands H bonds to a N or O atom in guanine

Question 15

DNA Replication

Answer 15

process by which a double stranded DNA molecule is copied to produce 2 identical DNA molecules

Question 16

How does Cisplatin stop Cancer

Answer 16

Attached to guanine residues in DNA prevents Replication - enzymes cannot copy this base

Cell the enters programmed cell death and is destroyed

Question 17

Risks of anticancer drugs

Answer 17

Damage normal cells as well as cancer cells - drug given in short bursts to allow time between treatments

Lose hair and some cause perm or temp sterility

Question 18

Resistance of Cisplatin

Answer 18

Cancer cells develop resistance, limited use

Bond cisplatin to aspirin - Asplatin
Used to treat cancer cells resistant to cisplatin

Question 19

Aspirin

Answer 19

Manufactured by Salycilic Acid with Ethanoic Anhydride

Question 20

Method For Manufacturing Aspirin

Answer 20

•place 20g 2-hydroxybenzoic acid in pear shaped flask and add 40cm3 ethanoic anhydride

•add 5cm3 conc phosphoric(v) acid, slowly

•heat under reflux 30min

•add water to hydrolyse any unreacted ethanoic anhydride to ethanoic acid - pour mixture onto 400g crushed ice in beaker

•remove solid prod by suction filtration and wash with cold solvent

•recrystallise product using minimum volume of hot solvent - filter thorough food filter paper and allow to cool and crystallise - suction filter to obtain - wash with cold solvent and dry in desiccator

•determine mp to check purity

Question 21

Volumetric Determination of Aspirin Conc

Answer 21

Sol weak acid may be titrated with strong alkali (NaOH) using phenolphthalein

Conc of aspirin solution may be calc

Mol NaOH = Mol aspirin

Question 22

Back Titration Aspirin

Answer 22

When NaOH added, ester group may be hydrolysed as well as acid group reacting w/ alkali

Excess alkali may be added - mixture warmed to hydrolyse ester group

1mol aspirin react with 2mol NaOH - excess may be back titrated with HCl

Question 23

TLC to test Drugs

Answer 23

•sample of synth aspirin placed in test tube and dissolved in small vol of suitable solvent to make conc sol

•sample of pure commercial aspirin dissolved in ethanol in another test tube

•pencil line drawn 1cm from bottom TLC plate with 2 X

•each sample spotted onto X’s - wait few moments to let solvent evaporate

•plate placed in beaker with lid and suitable solvent at bottom (ethyl ethanoate)

•when solvent close to top, remove it and mark position solvent front

•use UV light or dev agent to identify spots on TLC plate

•Rf values calc by dividing dostance moved by spot by solvent front

only one spot for synth aspirin good indication its pure

Question 24

GLC-MS

Answer 24

Gas-liquid chromatograph is attached to the mass spectrometer

Retention time the same but impurities may have same - mass spectrometer would not match however

Question 25

Haemaglobin

Answer 25

Complex of iron(II) ion surrounded by a porphyrin ring Iron(II) ion can accept 6 pairs electrons from ligands Porphyrin ring contains 4 N atoms - can form 4 coord bonds with Fe Amino acid in a protein chain forms fifth coord bond to iron(II) ion surrounded by

Question 26

Oxyhaemoglobin

Answer 26

Each Fe2+ containing haem can accept a pair of e- and form coord bond with Oxygen Conformation changes allow it to bind more oxygen at diff sites

Question 27

Carboxyhaemoglobin

Answer 27

200 more times stable than oxyhaemaglobin When incomplete combustion occurs and CO is prod and inhaled - people poisoned because stable CHG prevents blood from carrying O2 Cause if death in almost all house fires

Question 28

Edta

Answer 28

Can form complex with Ca2+ Ca2+ + edta4- -> [Ca(edta)]2- Ca2+ important in blood clotting mech - activation of platelets Edta is chelating agent - highly stable complex with Ca2+ Removing hy sequestering with edta means not available for blood clotting

Question 29

Sequestering

Answer 29

formation of a complex so that an ion is no longer available for reactions Blood banks use to prevent stored blood from clotting