BIO 202 Lecture 2

• Hydroxyl is OH and is polar
• Carbonyl is CO and is polar
• Carboxyl is COOH and is negatively charged
• Amino is NH2 and is positively charged
• Sulfhydryl is SH and is polar and participates in S-S bonds
• Phosphate is PO4 and is negatively charged and bulky.
• An example of simple sugars is glucose.
• Sugars are carbohydrates and has a ratio of 2:1
• Glucose can be found in cellulose of cell walls, glycolipids and glycoproteins in cell membranes
• Polysaccharides are made from sugar monomers by the removal of water called condensation synthesis.
• Fatty acids are sources of food and the produce more energy than glucose.
• Fatty acids are part of phospholipids
• Fatty acids are stored as triglycerides and phospholipids
• If the fatty acid has no double C=C bonds it is saturated
• If the fatty acid chain has double C=C bonds, it is unsaturated
• The structure of a phospholipid has a hydrophilic head and a hydrophobic tail
• The double bond in unsaturated fatty acid chains bend, which results in a kink preventing close packing of phospholipids.
• When phospholipids are placed in aqueous environment, they form a phospholipid bilayer.
• Hydrophobic tails face each other and hydrophilic heads face towards the water.
• Sterols include cholesterol
• Sterols contribute to membrane fluidity and rigidity due to their bulky structure.
• Sterols are precursors to steroid hormones.
• Nucleotides function as energy carrier, signals, and subunits of DNA and RNA
• Pyrimidines are cytosine, thymine, and uracil. They have 6 membered rings
• Purines are adenine and guanine. They have 5 membered rings attached to 6 membered ring.
• A nucleoside contains a base plus a sugar
• Carbons 3 and 5 of a nucleoside are functionally very important.
• In DNA, the sugar is deoxyribose which lacks oxygen at position 2.
• In RNA, the sugar is ribose which has oxygen at position 2.
• Thymine has a methyl group at position 5, while uracil has a hydrogen at position 5
• Deoxyribose lacks oxygen at position 2
• To turn a nucleoside into a nucleotide, esterification occurs at position 5
• The backbone of DNA is a phosphate group and a sugar. This stays constant
• The base of a nucleotide can change
• Nucleic acids are found in the nucleus, cytoplasm, mitochondria, chloroplasts, and ribosomes
• Nucleic acids store genetic information, transfers genetic information, for structural, for transport, for enzyme activities, and for gene regulation.
• Linear DNA and RNA are polar. They have 5' end with phosphate group and 3' end with OH group
• DNA is a double helix with the bases on the inside caused by hydrogen bonds
• C-G pairing is stronger and more stable because they use 3 bonds
• A-T uses 2 hydrogen bonds