The chemistry of life

1. The chemistry of life Topic 3

2. The four main elements of life… • Hydrogen - H • Carbon - C Electron Proton Neutron • Oxygen - O • Nitrogen - N

3. Image sources • Carbon block - http://www.carboncycle.biz/images/element-carbon.jpg • Hydrogen gas - http://www.webelements.com/_media/elements/element-pics-theo/1_H_2.jpg • Nitrogen gas - http://periodictable.com/Samples/007.4/s12s.JPG • Oxygen gas - http://easycalculation.com/chemistry/elements/images/oxygen.jpg

4. Other elements used in life • Phosphorus P Part of the amino acid methionine • Sulphur S Part of a phospholipid (Plants and animals) • Iron Fe • Sodium Na • Calcium Ca Part of salt – plays a role in osmotic balancing. Part of haemoglobin in the blood Part of the bones Iron – Blood cells - http://singularityhub.com/wp-content/uploads/2008/08/red-blood-cells.bmp Sodium – spoonful of salt - http://images.medicinenet.com/images/SlideShow/salt_shocker_s1_spoon_salt.jpg Calcium – Bones - http://www.high-pasture-cave.org/images/work/AmphibBones.jpg Sulphur – Methionine structure - http://upload.wikimedia.org/wikipedia/commons/thumb/a/aa/Methionine.png/200px-Methionine.png

6. Water The angle between the hydrogen nuclei and oxygen nucleus is 104.3o The size of the hydrogen shell that the electrons whizz around is considerably smaller than the oxygen shell. The electrons therefore spend more time around the oxygen atom than the hydrogen atom making that end of the molecule ‘+ve’ charged and the oxygen ‘–ve’ charged – a polar molecule.

7. Hydrogen bonding in water + + + + + + + + + + • The positive hydrogen ends of each water molecule are attracted to the negative oxygen ends of other water molecules. This makes water molecules stick together. This stickiness is called hydrogen bonding and leads to many properties: • Surface tension • Cohesion • High specific and latent heat capacity. • The excellent solvent properties. - - - - -

8. Surface tension and Cohesion Because the water molecules stick together by hydrogen bonds it means that if you pull one water molecule it will pull others. This is important in plants to get water from the roots to the leaves and creates surface tension for insects to walk on water Giorgio Carboni, Surface phenomena and colloids, http://www.funsci.com/fun3_en/exper2/exper2_11.jpg Lea L Anderson - Ambiente: Água, http://farm1.static.flickr.com/220/503685059_39c8a1a6e8.jpg Fred Liebenberg - Water Strider. http://img1.eyefetch.com/p/5l/452439-5a22e180-a079-43b1-a978-6b3877a7385e.jpg

9. Thermal properties of water • The hydrogen bonds in water means it takes lots of energy to heat it up. This is a high specific heat capacity. As a result water is a Thermal buffer. Daily temperature variation in a forest (red) and a pond (blue) John Burrel - http://click4biology.info/c4b/3/Chem3.1.htm Why is thermal buffering important to living organisms? Chicago Acupuncture Pregnancy http://www.harmonyhealth.us/filebin/1605074.pregnant%20belly.jpg

10. The hydrogen bonds in water means it takes lots of energy to make it evaporate. This is a high latent heat of evaporation. • When you sweat the heat energy from your body goes into the water. Lots of heat energy makes the water evaporate. As it evaporates it takes the energy away. Jenna Hartman http://my.hsj.org/Schools/Newspaper/tabid/100/view/frontpage/schoolid/3288/articleid/356356/newspaperid/3401/Dreading_the_sweating_The_things_you_may_not_have_known.aspx

11. Solvent properties of water Because of the polarity of the water molecule the ‘-ve’ end of the molecule will be attracted to ‘+ve’ ions and will surround them in shells. Also the ‘+ve’ end of the water molecule will be attracted to ‘-ve’ ions. This will isolate ions in a ‘solution’. Water is a universal solvent. This is very important so that water is used as a transport medium: In plants carrying minerals from the soil In animals carrying nutrients in the blood. Niel. Water, Part III, the solvent of life. http://www.dangthatscool.com/wp-content/uploads/2009/08/hyd_nawiki.jpg For more look at this web site: http://www.dangthatscool.com/2009/08/02/water-part-iii-the-solvent-of-life/

12. What is this? • Glucose • Ribose • Amino Acid • Fatty Acid http://click4biology.info/c4b/3/images/3.2/glucose.gif http://www.synapses.co.uk/genetics/xibose.gif

13. Glycerol and fatty acids make a lipid This releases water (in this case 3 molecules.)

14. Click on these hotlinks to watch animations of how molecules join and break apart. • Monosaccharide joining together by condensation http://www.biotopics.co.uk/as/disaccharideformation.html • Disaccharides breaking apart by hydrolysis http://www.biotopics.co.uk/as/disaccharidehydrolysis.html • Amino Acids joining together to make a dipeptide by condensation http://www.biotopics.co.uk/as/aminocon.html • Dipeptide breaking apart to form amino acids by hydrolysis http://www.biotopics.co.uk/as/dipeptidehydrolysis.html

15. Summary of Hydrolysis and Condensation Produces water Hydrolysis Hydrolysis Uses water

16. Sugar Examples • Three examples of sugars: Monosaccharides • glucose, galactose and fructose Disaccharides • maltose, lactose and sucrose Polysaccharides • starch, glycogen and cellulose.

17. Sugar Functions: Animals • Glucose Immediate energy • Lactose Milk sugar • Glycogen Long term energy store • Plants • Fructose • Part of nectar • Sucrose • Transport of sugar in phloem • Cellulose • Forms cell wall

18. Functions of Lipids Pull my finger Santa, www.baronbob.com http://www.baronbob.com/pmfsantabig.jpg 1. Thermal Insulation 2. Electrical Insulation 3. Protection 4. Source for Steroid hormones http://www.naturalhealthschool.com/img/nervecell.gif http://www.woodka.com/wp-content/stuff/nike3_081205_big.jpg2.jpg Ekim Sokahalv, Best Steroids. http://www.isteroids.com/images/best-steroids.jpg