Metabolic Processes

1. Metabolic Processes • What does that mean?? • The cell is a highly organized assembly of atoms and molecules programmed by genetic instructions to carry out chemical reactions that define “life”. • Living organisms are characterized by a balance of anabolism and catabolism. Together, they are called metabolism.

3. Metabolic Processes:Chemistry of Life Monday, March 1st Miss Tee

4. Chemical Fundamentals

5. Chemical Fundamentals

6. The Atom • Mass number: # protons, neutrons • Atomic number: # of protons • Isotope: atom of an element with same atomic number but different mass number

7. Isotopes • Nucleus of some isotopes spontaneously decays • We call these radioisotopes and they are radioactive • Radioactivity results in: • Formation of new element • Release of subatomic particles • Radiation

8. Isotopes

9. Half-life • Every radioisotope has a characteristic property: half-life • What is a half-life? • The time it takes for ½ atoms in a sample to decay • What application does this have for us today? • Radioisotopes emit radiation as they decay  can be detected • Radioactive tracers are used to follow chemicals through reactions as they occur in the body • BIG medical research industry

10. Chemical Bonding • Orbital • Volume of space where electrons are most likely to be found • Can accommodate no more than 2 electrons • When 2 electrons pair up and occupy an orbital = more stable • Ion • Cation, anion (loss, gain of e-) • Ionic bond • Force of attraction between anion and cation • NaCl

11. Ionic Bonding

12. Covalent Bonding • Atoms share electrons in outer shell, creating full shells for both • Diamond is a good example

13. Molecular Shape • Overall shape contributes to molecule behaviour • When atoms react to form covalent bonds, their valence electrons undergo “hybridization” • Change in orientation of the valence electrons • Since electrons are all –vely charged, the pairs will repel each other and will move as far apart as possible • Molecular shapes include: • Tetrahedral • Pyramidal • Angular • Linear

15. Water • H2O’s polar covalent bonds and asymmetrical shape create a highly polar molecule • Allows it to form chemical bonds with other molecules and ions • Bonds BETWEEN molecules are called “intermolecular bonds” • Intermolecular bonds weaker than intramolecular bonds • 3 types: • London Forces • Dipole-dipole forces • Hydrogen bonds

16. London Forces • Weakest, exist between all atoms and molecules • Formed by temporary unequal distribution of electrons as they move randomly about the nucleus • Transient “electron cloud” will attract positive nucleus of neighbour atom

17. London Forces

18. Dipole-dipole Forces • Hold polar molecules together • Partially positive side of a molecule attracts the partially negative side of another molecule

19. Hydrogen Bonds • Especially strong dipole-dipole forces • Form only between electropositive H of one molecule and an electronegative N, O, or F atom of neighbour polar molecule

20. Hydrogen Bonds

21. Van der Waals forces • London forces, dipole-dipole forces and hydrogen bonds are collectively referred to as “Van der Waals forces” • Electrostatic charges between adjacent atoms

22. Water as a Solvent • Small non-polar molecules (O2, CO2) cannot form hydrogen bonds with water  only slightly soluble • That is why we need hemoglobin • Large non-polar molecules (fats, oils) also do not form hydrogen bonds • “hydrophobic” (opposite is…?)

23. Unique Properties of Water • Water clings • Cohesion • Adhesion • Water absorbs a lot of heat • High specific heat capacity • High specific heat of vaporization • Solid water is less dense than liquid water

24. Unique Properties of Water • Homework: • Make a table listing the 5 unique properties of water with: • A definition for each property • The effect of that property • An example of that property in everyday human or animal life • Prepare your unit glossary

25. Acids, Bases and Buffers • At 25°C, 2 H2O molecules/ 550 million react with each other • 1 H2O donates an H+ to the other H2O molecule  OH-, H3O+ • This is called “autoionization”

26. Acids, Bases and Buffers • What is an acid? Base? • An acid is a proton donor; a base is a proton accepter • What do you know about pH and the human body? • Internal environment of multicellular organisms is very sensitive to pH levels • Most cellular processes operate best at pH 7.0- 7.4 • Living cells use “buffers” (proton accepting/donating system) to resist significant changes in pH

27. Acids, Bases and Buffers • The most important buffer to the human body is carbonic acid (H2CO3) and bicarbonate (HCO3-) buffer system

28. Buffers • Acidosis and alkalosis can be serious medical conditions, potentially fatal • Internal buffers can donate H+ ions when they are required (if a patient is alkalotic) and can remove H+ ions when there are too many in a solution (if a patient is acidotic). • They are reversible reactions.