Chapter 2 - Biochemistry

1. Chapter 2 - Biochemistry Wakefield 2010-2011

2. Nature of Matter (2.1) • Life Depends on chemistry - • The science of matter and the changes it undergoes

3. Nature of Matter (2.1) • Matter - everything around you - anything made of atoms and molecules • Atoms – the basic unit of matter • Means unable to be cut • First referred to by the Greek philosopher, Democritus about 2500 years ago • Made up of sub-atomic particles

4. Nature of Matter (2.1) • Atoms – the basic unit of matter • Made up of sub-atomic particles • Protons – located in the nucleus of the atom and have a (+) positive charge • Neutrons – located in the nucleus of the atom and have a (+/-) neutral charge • Electrons – located in orbit around the nucleus of the atom and have a (-) negative charge • Nucleus – the center of the atom

5. Nature of Matter (2.1) • Atoms – the basic unit of matter • Atoms are usually neutral in charge because the # of positively charged protons and the # of negatively charged electrons are equal – giving the atom a neutral charge

6. Nature of Matter (2.1) • Element - pure substance containing only one type of atom – indicated by a chemical symbol or abbreviation • More than 100 known elements • Only about 2 dozen commonly occurring elements

7. Nature of Matter (2.1) • Element - pure substance containing only one type of atom • Atomic Number – indicates the # of protons present • Atomic Mass - indicates the sum of the protons and neutrons in the nucleus (Protons + Neutrons = Mass #) • Atomic Mass is also an average of the protons and neutrons as they naturally occur

8. Nature of Matter (2.1) • Isotopes – occur when atoms of the same element have different numbers of neutrons – identified by their atomic mass number Nonradioactive carbon-12 Nonradioactive carbon-13 Radioactive carbon-14 6 electrons 6 protons 6 neutrons 6 electrons 6 protons 7 neutrons 6 electrons 6 protons 8 neutrons Carbon 12 Carbon 13 Carbon 14 See Figure 2-2 – page 36

9. Nature of Matter (2.1) • Radioactive isotopes – occur because the nucleus of these atoms become unstable and start to break down over time Nonradioactive carbon-12 Nonradioactive carbon-13 Nonradioactive carbon-14 6 electrons 6 protons 6 neutrons 6 electrons 6 protons 7 neutrons 6 electrons 6 protons 8 neutrons (See Figure 2-2 – page 36)

10. Nature of Matter (2.1) • Radioactive isotopes – • Unstable and break down over time • Give off radiation that can be dangerous • Can be practical and useful • Treat Cancer • Kill Bacteria • Used as labels & tracers to follow movement of substances within organisms

11. Nature of Matter (2.1) Radiation Therapy

12. Nature of Matter (2.1) • Compounds – a substance formed by the chemical combination of 2 or more elements in definite proportions • Indicated by a chemical formula • H2O, CO2 • Properties of a compound are usually very different from those of the elements from which it is formed • NaCl for example

13. Nature of Matter (2.1) • Chemical Bonds – atoms in compounds are held together by chemical bonds • Involves the electrons that orbit the nucleus of the atoms involved in the bond

14. Nature of Matter (2.1) • Chemical Bonds – atoms in compounds are held together by chemical bonds • Ionic Bonds – formed when one or more electrons are transferred from one atom to another Salt Na+Cl-

15. Nature of Matter (2.1) • Chemical Bonds – atoms in compounds are held together by chemical bonds • Covalent Bonds – formed when electrons are shared between atoms • Single Covalent Bond - formed when only 2 electrons are shared in the bond • Double Covalent Bond – formed when 4 electrons are shared in the bond • Triple Covalent Bond – formed when 6 electrons are shared in the bond (rarely does this occur) 3-D molecular structure of H2O

16. Nature of Matter (2.1) • Molecule – substance formed from bonding of elements and is the smallest part of a compound

17. Nature of Matter (2.1) • van der Waals – intermolecular bonding

18. Properties of Water (Section 2.2) Page 40

19. Earth – “the blue planet”

20. Properties of Water 2.2 • Water • Covers ¾ of the earth’s surface • One of the few compounds that is liquid in most of our environments • Expands when it freezes so it floats • Evaporates when it is heated

21. Properties of Water 2.2 • Water • Molecule of water is neutral in charge • Water does have polarity • Occurs when there is an uneven distribution of electrons between the oxygen and the hydrogen atoms • Water molecule is bent in shape • Oend has a slightly negative (-) charge • H end has a slightly positive (+) charge

22. Properties of Water • Cohesion – an attraction of like molecules

23. Properties of Water • Adhesion – the attraction between molecules of different substances.

26. Properties of Water Adhesion >>>>>> Capillary Action • Capillary Action – adhesion between water and another substance – will draw water up that substance • Ex. Water up the stem of a plant to the leaves

27. Mixtures, Solutions & Suspensions • Mixture – a material composed of two or more elements or compounds that are physically mixed together but not chemically combined • Other • Types of Mixtures • Solutions • Suspensions

28. Mixtures, Solutions & Suspensions • Solution – • Components are evenly distributed • Contains: • Solute - substance getting dissolved • Solvent – Substance which dissolves the solute Cl- Cl- Na+ Na+ Water Water

29. Mixtures, Solutions & Suspensions • Suspension - occurs when solute breaks into tiny pieces - some so small they cannot be seen – they then stay suspended in the solvent . . . . . . . . But will eventually settle out of suspension.

30. Acids, Bases & pH • Acid – any compound that forms H+ ions in solution • Base – a compound that produces hydroxide ions (OH- ions) in solution • pH – measurement to indicate the concentration of H+ ions in a solution • Buffer – weak acids or bases that can react with strong acids or bases to prevent sharp, sudden changes in pH