Topic 4:Chemicals of life

1. Topic 4:Chemicals of life Molecules and Atoms Water Carbon and other elements

2. 1. Atoms and Molecules 1.1 Elements and Compounds 1.2 Elements of Life 1.3 Chemical and Physical Bonds 1.4 Importance of Carbon, Nitrogen, and Water

3. 1.1 Elements and Compounds cannot be broken down to other substances by chemical reactions Elements combine to form compounds. Matter is made up of elements. Organisms are composed of matter. anything that has mass and takes up space

4. + Sodium Chloride Sodium Chloride Emergent Properties compounds have characteristics different from those of their elements

5. 1.2 Elements of Life Essential Elements (elements required by living organisms) • trace elements • Fe, I, Cu, Mn, etc. • required in minute (tiny) amounts • microelements • Na, K, Ca, Mg, P, S, Cl • 4% of living matter • macroelements • C, H, O, N • 96% of living matter

6. the properties of elements depend on the chemical characteristics of their atoms

7. chemical characteristics of atoms depend on the arrangement of electrons in electron shells (electron configuration)

8. Electronegativity • the attraction of an atom for electrons from other atoms • important property of elements of life

9. 1.3 Chemical and Physical Bonds Bonds Chemical Bonds Physical Bonds form between elements form between molecules Covalent Ionic Dipole Interactions Van der Waals

10. Chemical Bonds Ionic Bonds Covalent Bonds elements of similar electronegativity share pairs of electrons elements of very different electronegativity transfer electrons, creating ions (anions and cations)

11. The properties of a compound (solubility, melting point, etc.) depend on the type of bonding involved.

12. Covalent bonds are the most important in biological molecules because they allow for a variety of properties single covalent bond H O H O double covalent bond N N triple covalent bond they can be single, double, or triple bonds

13. Covalent bonds can be classified as non-polar or polar water non-polar covalent bonds (elements of the same or almost the same electronegativity) polar covalent bonds (elements of slightly different electronegativity) ethane create dipoles - molecules with partial negative (𝛿-) and positive (𝛿+) charges at opposite ends

14. weak attractions between molecules (not the result of chemical reactions) Physical Bonds

15. There are two major types of Physical Bonds Dipole Interactions Attraction between opposite poles of polar molecules (dipoles) Van der Waals Interactions (aka London Dispersion Forces) Caused by momentary asymmetric distribution of moving electrons in large non-polar molecules.

16. H Water (H2O) O H  +  – Ammonia (NH3) N H H d+ + H Hydrogen Bonds  –  + • the most important dipole interaction in biology • forms when a hydrogen atom covalently bonded to one electronegative atom is also attracted to another electronegative atom from a different molecule  +

17. bonds determine the shape of the molecule

18. Shape of a Molecule • determines the biological function • Differently-shaped molecules have different functions • similar shape molecules can mimic the function of another molecule (morphine/endorphins)

19. 1.4 Importance of C, N, and H2O inorganic carbon (CO2) autotrophs organic carbon (glucose) heterotrophs Carbon is the element most widely used in biomolecules due to its special properties. Organisms can obtain carbon in two ways:

20. inorganic nitrogen (N2) atmosphere – microorganisms, fungi minerals – nitrates for plants organic nitrogen from other organisms Nitrogen is also essential to living organisms, making part of proteins and nucleic acids. Organisms can obtain nitrogen in two ways:

21. Water • fundamental to life • organisms are composed mostly of water (65% in humans, 99% in jellyfish) • most chemical reactions in organisms take place in water (wet chemistry)