1. Chemistry of Life…and some Biology

2. Fundamental Building Blocks Elements-can’t be broken down by chemical reaction Atoms-basic unit of an element Atomic number- the number of protons in the atom

3. Atoms Atoms are composed of protons, neutrons, electrons (e - ) Electrons are located in shells around the nucleus. The electrons closest to the nucleus are held close, those further away have more energy and less attraction to the protons in the nucleus

4. Atoms and Their Energy As atoms get more stable they have less energy Atoms are more likely to react with each other when they have more energy (i.e. less stable) An atom becomes stable when its outermost shell is filled or loses enough electrons to lose its outer shell Which of the above are the most stable?

5. Atoms and Their Energy Lets look at sodium… Sodium (Na) has 11 protons (how can you tell this?) In its free state it has 11 protons and 11 electrons making it neutral. Due to lack of stability the outer most electron can be lost and Na can have 11 neutrons and 10 electrons This is an ion, a charged but stable atom In this case Na would have a +1 charge

6. Bonding Atoms tend not to just gain and lose electrons. For example for Na to lose its outermost electron it needs to be around an atom that will pick up, or gain, that electron. Look at Chlorine (Cl) on the chart. Can you see why Na and Cl combine to make NaCl? This is an example of an ionic bond. There are 3 types of bonds we will discuss: Ionic Covalent Hydrogen

7. Ionic Bonds Form between positive and negative ions One atom is losing an electron and another is gaining an electron Strongest chemical bond

8. Sharing of electrons between atoms Less strong than ionic bonds Occurs when there are 2 or more reactive atoms that both become stable by gaining electrons Rather than being selfish they share the electrons Covalent Bonds

9. There are many important covalent bonds in biology One of the most common is the one between Carbon (C) and Hydrogen (H) Covalent Bonds

10. Polarity occurs when there is a slight difference of charge across the molecule Polarity occurs when one of the atoms has less of an affinity for the electrons than the other atom in the bond Ex: in water oxygen (O) has more affinity for the electrons than the hydrogen (H) does causing a lightly more negative area by the O and a slightly more positive area by the H. Covalent Bonds and Polarity

11. Due to this polarity hydrogen bonding can occur. This is the least strong of the bonds we talk about. These hydrogen bonds give water some of its important characteristics Polarity and Hydrogen Bonds

12. Compounds will dissolve in water if they: Are polar and will form hydrogen bonds with the water Are in an ionic bond These are hydrophilic compounds Non-polar compounds do not dissolve in water and are considered hydrophobic Water is the solvent in this case and NaCl is the solute Water Table salt (NaCl) in Water (H 2 O)

13. pH is referring to the number of H + in a liquid In an acidic solution there are many H + In a basic solution there are many OH - which grab up the H +, thus decreasing their concentration pH Scale

14. Concentration Gradient Difference in concentration of molecules in one area compared to another

15. Diffusion Small substances diffuse faster than larger substances Heat increases the rate of diffusion The greater the difference in concentration of two substances, the greater the rate of diffusion

16. Selective Permeability Selective about what crosses based on: Size Electrical charge Other properties

17. Osmolarity

18. The Chemical Building Blocks of Life Four major classes of molecules are essential to life: Carbohydrates* Proteins* Lipids Nucleic acids Each of these molecules is made up of varying combinations of carbon, hydrogen, oxygen, nitrogen, phosphorus, and sulfur *we will only talk about these today. We have talked about lipids, and will talk about nucleic acids at a later date.

19. The Chemical Building Blocks of Life The vast array of biological processes are dependent on a carbon-carbon framework with small amounts of other atoms attached An organic molecule is one that contains at least one carbon- hydrogen bond Living cells contain many types of organic molecules

20. The Chemical Building Blocks of Life Small organic molecules can bond to other organic molecules to form macromolecules Macromolecules are made up of building blocks called polymers, which contain small, repeating organic molecules known as monomers The properties of organic polymers depend on the clusters of atoms covalently bonded together, called functional groups

21. Carbohydrates Sugars are a source of stored energy and are called carbohydrates Sugars are found in almost every cell and is involved in every chemical reaction that produces energy in living organisms

22. Carbohydrates Glucose is a type of simple sugar called a monosaccharide Table sugar is an example of a disaccharide, which is formed when two monosaccharides, glucose and fructose, are covalently bonded Polysaccharides are large polymers built by linking many monosaccharides together

23. Carbohydrates Cellulose and starch are both found in plants and made from glucose, but differ in the way the monosaccharides are linked Glycogen is a highly branched polysaccharide that stores energy in animal cells for rapid release when needed

24. Proteins Proteins are categorized by the function they perform: Storage Structure Transport Catalysis

25. Proteins Are Built from Amino Acids All proteins are built from monomers called amino acids There are 20 different amino acids that can be arranged in a multitude of ways to construct the variety of proteins needed for life

26. Proteins Are Built from Amino Acids Amino acids differ only in the type of R group that they include The R group gives each protein its unique properties and can vary from having just one atom to complex ring structures

27. primary structure secondary structure tertiary structure quaternary structure A Protein Must Be Correctly Folded to Be Functional

28. The sequence of amino acids in a polypeptide is known as the primary structure

29. A Protein Must Be Correctly Folded to Be Functional The secondary structure is created by the regional folding of the polypeptide into three-dimensional patterns

30. Is Secondary Structure that Important?

31. A Protein Must Be Correctly Folded to Be Functional The tertiary structure is formed by the interactions of distantly placed segments of the polypeptide chain

32. A Protein Must Be Correctly Folded to Be Functional Certain proteins have a quaternary structure created by the interaction of another polypeptide chain Denaturation is the destruction of a protein’s three-dimensional shape, resulting in a loss of protein activity Extreme temperatures, pH, and salt concentration can cause denaturation of proteins