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BIOL 2020 (121)
Lecture

Section 1.docx

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Department
Biology
Course
BIOL 2020
Professor
Patrice Cote
Semester
Fall

Description
Section 1 December-08-11 10:46 AM Four types of biological molecules  Carbohydrates (sugars) o Monosaccharides  (CH2O)n  A single monomer o Disaccharides  Ex. Sucrose  Two monomers o Oligosaccharides  A small chain of 3-10 monomers covalently attached to lipids and proteins  Can attach to lipids, and proteins  Are found near the surface of the cell  They're like a cell's ID tag o Polysaccharides  Composed of many monomers  Many different polysaccharides can be formed with the same sugars, but using different bonds  Proteins  Nucleic acids  Carbs, proteins and nucleic acids start as monomers and combine into polymers  Lipids o Soluble in certain organic solvents o Not soluble in water o Fats  Composed of three fatty acid tails bound to a glycerol moiety via ester bonds  Used mainly as energy stores  Stores in cells called adipocytes  Fatty Acids  Are amphipathic  Hydrocarbon chain  Hydrophobic  Carboxyl group (-COOH)  Hydrophilic  Kinks in fatty acid tails are C=O  Cis-fatty acid  Kinked unsaturated fatty acid  Liquid at room temperatire  Trans-fatty acid  Unsaturated, but not kinked C=C bond  o Steroids  Cholesterol is the best known steroid  Found in membranes  Sits between fatty acid tails  Makes the membrane more rigid  Is amphipathic because of its OH group  The rest of the cholesterol is hydrophobic  This causes molecules of cholesterol to clump together o Phospholipids  Composed of glycerol moiety with two fatty acid tails, a phosphate group, bound to a polar head group  Fatty acid tails hydrophobic, the rest is hydrophilic  Are the basic building blocks of cells Building blocks of macromolecules  Monosaccharides --> Polysaccharides  Fatty acids --> Lipids  Amino acids --> Proteins  Nucleotides --> Nucleic Acids Amino acids  Alpha carbon bound to: o Carboxyl group o Amino group o R group (side chain) o Hydrogen  Types of R groups o Polar charged  Hydrophilic, acts as acid or base, full charge (+ or -), form ionic bonds and tend to be involved in chemical reactions o Polar uncharged  Hydrophilic, partial charge (+ or -), can participate in chemical reactions, form H bonds and associate with water  Usually faces outside of protein o Nonpolar  Hydrophobic, forms the inner core of soluble proteins. Associates with lipid bilayer in membranes  Points towards lipids, or inner core of protein o Unique properties  Glycine  Single H, fits in hydrophilic or hydrophobic environment, at sites of close contact between two polypeptides  Makes polypeptide chain flexible  Cysteine  Can form a covalent link with another cysteine to form a disulfide link  Proline  Has a cyclic structure; bonds from alpha carbon to the N group on an amino acid  Produces a kink in the chain  Will eventually disrupt the secondary structure of a protein  Join via peptide bonds o H of Amino group binds to OH of carboxyl group
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