1 Molecular basis of life (1)

2 Chemical basis of molecular interactions Polar and nonpolar molecules Water Universal solvent O-H bonds are polarized Partial positive and negative charges

3 Chemical basis of molecular interactions Polar and nonpolar molecules Water is polar blank

4 Chemical basis of molecular interactions Polar and nonpolar molecules Hydrocarbons are nonpolar Properties are conferred by functional groups A functional group Behaves as a unit Confers physical properties, chemical reactivity, & solubility blank

5 Chemical basis of molecular interactions Noncovalent bonds Not based on electron sharing Attractive forces – readily broken and reformed Major classes Ionic bonds Hydrogen bonds Hydrophobic interactions and van der Waals forces

6 Chemical basis of molecular interactions Classification of Bio-Molecules by function Macromolecules Four major categories Carbohydrates Lipids Proteins Nucleic Acids Metabolic intermediates (metabolites)

7 Classification of Bio-Molecules Carbohydrates Simple sugars (monosaccharides) Small chains (oligosaccharides) Long chains (polysaccharides)

8 Classification of Bio-Molecules Carbohydrates Simple sugars (monosaccharides) Linking simple sugars by covalent glycosidic bonds – form : Small chains (oligosaccharides) Long chains (polysaccharides)

9 Carbohydrates Linking simple sugars by covalent glycosidic bonds

10 Carbohydrates Glycogen Branched polymer containing only one type of monomer – glucose Starch – in plants Amylose Unbranched, helical Amylopectin Blank

11 Classification of Bio-Molecules Lipids Important categories Fats Steroids phospholipids

12 Lipids Fats – Structure Glycerol molecule + 3 fatty acids (ester bonds) Triacylglycerol

13 Lipids Fats – Fatty Acids Long, unbranched hydrocarbon chains Single terminal carboxyl group Each end has very different structure and properties Hydrocarbon chain is hydrophobic Carboxyl end group is hydrophilic Termed amphipathic

14 Lipids Fats A Fat molecule may have the same FA or mixed FA High energy reserve One gram of fat contains over twice the energy of one gram of carbohydrate – lack water. Stored in specialized cells – adipocytes

15 Lipids Steroids Built around a characteristic four ring hydrocarbon skeleton Cholesterol Precursor for steroid hormones

16 Blank Lipids Phospholipids A diacylglycerol structure Third hydroxyl group on the glycerol is covalently bonded to a phosphate group – then linked to a small polar group (eg. Choline)

17 Nucleic Acids Macromolecules – long strand of monomer nucleotides Primary function – storage and transmission of genetic information Also structural and catalytic roles Two types Deoxyribonucleic acid – DNA Ribonucleic acid - RNA Classification of Bio-Molecules

18 Nucleic Acids RNA – will serve as the example

19 Nucleic Acids RNA Each nucleotide has three parts A five-carbon sugar – ribose A nitrogenous base (having N in the ring structure of the molecule) A phosphate group

20 Nucleic Acids RNA Each nucleotide has three parts Phosphate linked to the 5’ carbon of ribose The nitrogenous base is linked to the 1’ carbon of ribose Blank

21 Nucleic Acids RNA During the assembly of the nucleic acid strand The OH group on the 3’ carbon of ribose on one nucleotide is linked by an ester bond to the phosphate group of its neighbor The nucleotides are connected by sugar-phosphate linkages

22 Nucleic Acids RNA Nitrogenous bases Two groups Pyrimidines – smaller – single ring Purines – larger – two rings

23 Nucleic Acids RNA Nitrogenous bases Two groups Pyrimidines – smaller – single ring cytosine and uracil Purines – larger – two rings adenine and guanine DNA Thymine replaces uracil

24 Nucleic Acids Complementary Base Pairing Hydrogen bonding

25 Nucleic Acids RNA Consist of a single continuous strand Often folded back on itself Blank

26 Nucleic Acids Nucleotides not involved in building nucleic acids Adenosine triphosphate (ATP) – energy storage Guanosine triphosphate (GTP) – signal cascade