Unit 2 - Biochemistry

1. Unit 2 - Biochemistry Chapters 2 and 3 Biology: Concepts and Connections

2. Intro to BioChem DNA lipid carbohydrate protein

3. 2.1 Living Organisms are composed of about 25 chemical elements • Remember our biological hierarchy • Base of hierarchy was atoms, elements, molecules • Matter – anything occupying space and having mass • Element – substance that can’t be broken down to another substance (periodic table of elements) 25 chemical elements required for life • 96% Carbon, Hydrogen, Oxygen, Nitrogen (proteins, fats, and sugars) • 4% Calcium, Phosphorus, Potassium, Sulfur, Sodium (important biological functioning)

4. 2.3 Elements can combine to form compounds • Compound – Two or more elements in a fixed ratio. Bonded together • Example H20 Water is a compound because it consists of the elements hydrogen and oxygen in a 2:1 ratio One molecule of H20

5. 2.4 Atoms consist of protons, neutrons, and electrons • Atomic Structure • Important – The number of electrons and protons is always the same. This number is signified by the atomic number on the periodic table Electrons orbit the nucleus Protons and neutrons occupy the nucleus of the atom

6. 2.6 Electron arrangement determines the chemical properties of an atom. • Electrons in an atom occupy electron shells. • Depending on the number of electrons there may be several electron shells. • Shells can hold a specific number of electrons and your understanding of this is crucial for understanding chemical bonding.

7. 2.6 Continued – electron arrangement • For simplicity purposes we will worry only about the first three shells • Each shell can occupy, at max, the following number of electrons • The shells closest to the nucleus fill up first

8. 1 p 3 p 2 p 4 p 2.6 Continued – electron arrangement examples Lithium = atomic number 3 Hydrogen = atomic number 1 Helium = atomic number 2 Beryillium = atomic number 4

9. 10 p 6 p 8 p 2.6 Continued – electron arrangement examples Neon = Atomic number 10 Carbon = Atomic number 6 Sodium = Atomic number 11 Oxygen = Atomic number 8 11 p

10. 2.6 Continued – electron arrangement • Atoms who are not happy and how do they become happy? • Atoms who have outer shells that are not full (unpaired electrons) • Tend to interact with other atoms – chemical reactions • Outer shell rule – atoms tend to react with other atoms to fill their outer shells • Chemical bonds – attractions between atoms to ensure that outer shells are filled • This can be accomplished by giving and receiving electrons or by sharing electrons.

11. 2.8 Covalent bonds join atoms into molecules through “electron sharing” • Covalent bond – a chemical bond in which two atoms share one or more pairs of outer electrons. • Molecule – two or more atoms held together by a covalent bond

12. 2.8 Covalent bonds – single bonds • CH4 – molecular formula for “methane” Single covalent bond Electron Configuration Structural Formula

13. 2.8 Covalent bonds – double bonds • Oxygen molecule = O2 • Double bonds – electrons that share two pair of electrons to fill outer level Structural formula – Each line represents a shared pair of electrons

14. 2.8 Covalent bonds H – H H2 F – F F2 O = C = O CO2

16. Covalent Bonding Instructions • Write the symbols for each element. H H • Use M & M’s to show the number of valence electrons around each element H H • Rearrange the electrons (M and M’s) to form pairs H H

17. Covalent Bonding Instructions • Draw circles to show the sharing of electrons. • This symbolizes that both shells are • filled as a result of “sharing”. • Draw the structural formula using symbols & lines. • H-H • 6. Write the chemical/molecular formula. • H2 • Remove the M and M’s and use a color pencil • to symbolize the electrons. H H

18. 3.1 Life’s molecular diversity is based on the properties of carbon • Almost all molecules a cell makes are composed of carbon atoms bonded to one another • Carbons are connecting points in four directions • Because of carbon having four unpaired electrons it forms long very diverse molecules. (over 2 million)

19. 3.1 Life’s molecular diversity is based on the properties of carbon

20. 3.1 Life’s molecular diversity is based on the properties of carbon CH4 Ball and Stick model Structural formula Molecular Formula 3-D model shows angels 2-D model represents ratio of bonds represent shared of atoms in molecule electrons

21. 3.1 Life’s molecular diversity is based on the properties of carbon Butane C4H10 (lighter fluid) • Hydrocarbons • Hydrogen and Carbon Chains • Many possible combinations • Different combinations and shapes result in different properties

22. 3.3 Cells make a large number of large molecules from a small set of small molecules • Macromolecules – large molecules made from many covalently bonded atoms • Polymer – large molecule consisting of many “repeating” units called monomers. • Monomers are building blocks polymers. • Example: Trillions of different types of proteins (polymers) made from 20 different amino acids (monomers) • Example: DNA is made from 4 different monomers.

23. 3.3 Cells make a large number of large molecules from a small set of small molecules • Dehydration Synthesis Reaction – reaction responsible for joining monomers to polymers. During this reaction –OH (hydroxyl group) forms with a H atoms forming H2O

24. 3.4 Monosaccharides are the simplest carbohydrates • Four different classifications of biologically important macromolecules • Carbohydrates • Lipids • Proteins • Nucleic Acids

25. 3.4 Monosaccharides are the simplest carbohydrates • Carbohydrates - Large classification ranging from small sugar molecules (monosaccharide) to large polymers (polysaccharides) • Monosaccharides • CH2O – Hence carbo “hydrate” • Glucose, Galactose, Fructose = all C6H12O6 • Main fuel for cellular work (energy released when carbon – hydrogen bonds are broken) Blood sugar

26. 3.5 Cells link two single sugars to form disaccharides. • Carbohydrates cont’ • Dissaccharide – two monosaccharides joined together by dehydration synthesis. • Lactose—contains glucose and galactose • Maltose—contains two glucose molecules • Sucrose (table sugar)—contains glucose and fructose • Most efficient form for transportation in plants

27. 3.5 Cells link two single sugars to form disaccharides. Sucrose = glucose + fructose Table sugar Maltose = glucose + glucose Malt sugar Lactose = glucose + galactose Milk sugar

28. 3.6 How sweet is sweet? Chemical structure of sugar determines its shape, which determines how well its fits into a taste receptor.

29. 3.7 Polysaccharides are long chains of sugar units Polysaccharide – • polymers of monosaccharides • Break down as needed to obtain sugar • Ex. Starch • Many glucose monomers linked together

30. 3.7 Polysaccharides are long chains of sugar units • Obtaining energy from polysaccharide • Bonds must be broken between glucose molecules. Cells can absorb glucose because it is small. • Each time a Carbon Hydrogen bond is broken energy is released. (occurs in mitochondria) • Glycogen – “animal polysaccharide” stored in liver and muscles • Cellulose – “plant polysaccharide” • Forms “tough” cell walls. • In trees this forms the wood. • Fiber – can’t be digested but is “roughage”

31. 3.7 Polysaccharides are long chains of sugar units Glycogen – branched Cellulose – unbranched glucose is and glucose arranged in same direction arranged in same direction

32. 3.7 Polysaccharides are long chains of sugar units (Summary) • Starch – plant energy storage • Glycogen – animal energy storage • Cellulose – plant structural carbohydrate (cell wall)

33. 3.8 Fats are lipids that are mostly energy storage molecules • Lipid – diverse compound consisting of mainly carbon and hydrogen bonds. Hydrophobic (water fearing) • *Fats – energy storage and “cushioning” • Waxes – water barrier • Phospholipids – cell membrane • Steroids – human sex hormones

34. 3.8 Lipids as Fats • Fats • Large lipid made from two smaller molecules • Glycerol • Fatty Acid Fatty acids

35. 3.8 Lipids as Fats • Fat and triglyceride are synonymous • Glycerol bonded to three fatty acids • Energy storage!! 9 cal/gram…carbon – hydrogen bonds • More compact storage than carbohydrates

36. 3.8 Saturated vs. Unsaturated • Saturated – Solids…due to single bonds between Carbons (more compact) • “saturated” with hydrogen • Unsaturated – Liquid or Oil…due to double bonds between Carbons (not as compact • Not “saturated” with hydrogen

37. 3.8 Saturated vs. Unsaturated • Unsaturated • Liquid at room temp • Plant fats (sunflower oil, etc.) • Kink in chain causes less compaction • Saturated • Solid at room temp • Animal fat • Straight chains make solid

38. 3.8 Lipids and health • Saturated fats associated with atherosclerosis – lipid containing deposits build up on blood vessel walls. • Hydrogenated fats • Unsaturated fats that have had “hydrogens” added. Why??? • Also associated with heart disease.