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UIUC MCB 100 - The Chemistry of Microorganisms (cont.)

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MCB 100 1st Edition Lecture 8 Outline of Last Lecture I. Biological polymers II. Proteins III. Polysaccharides IV. Nucleic acids V. LipidsVI. Bonds that join biological polymers A. EsterB. –amide (peptide)C. phosphodiesterD. glycosidic VII. Water Outline of Current Lecture I. Amino acidsII. The folding of a protein to its final shape Current LectureI. Amino acids A. Proteins are linear chains of amino acids B. Typical proteins consist of 200-400 amino acids, but some are smaller than this and others are larger. Key factor that determines the structure ad ultimately the function of an enzyme is the sequence of amino acids found in the proteinC. All amino acids contain nitrogen in the form of an amino group. They also always have a carboxylic acid group (C=O-O-H) the amino groups and the carboxylic groups are involved in the formation of the bonds that join amino acids into long chains to make proteins. i. Glycine- R-group is small and hydrophobicii. Leucine- R-group is large and hydrophobiciii. Serine- R-group is small and polar D. There are 20 different amino acids commonly found in proteins (even though there's more than 100 different aa's found in cytoplasm that are not used in protein synthesis)E. All amino acids have the same basic shape, they differ only in the group labeled "R". For some amino acids "R" is large, for others, "R" is small. For some amino These notes represent a detailed interpretation of the professor’s lecture. GradeBuddy is best used as a supplement to your own notes, not as a substitute.acids "R" is polar and easily dissolved in water, for others, "R" is hydrophobic. For some, "R" is positively/negatively charged, for others "R" is not charged. F. Amino acids are grouped by types of side chains (non-polar/hydrophobic, aromatic- mostly hydrophobic, polar- hydroxyl/amide groups, acidic, sulfur containing, basic) G. Amino acids are held together by peptide bonds i. The formation of peptide bond requires a free carboxylic acid group and afree amino groupii. A molecule of water is produced when the 2 amino acids are joinediii. Note how the dipeptide has a free amino group and a free carboxylic acid group. Another amino acid can be attached by the formation of another peptide bondH. Since each amino acid has an amino group and a carboxyl group, a linear chain ofgreat length can be made (most proteins are chains of 100-1000 amino acids) II. The Folding of a Protein to Its Final Shape A. Primary structure i. The sequence of amino acids in the chainii. Determined by the genetic information encoded in the mRNAiii. Determines the final shape and function of the proteinB. Secondary structurei. Local folding of a protein chainii. Alpha helix and Beta sheet are common motifs iii. Stabilized by the interactions between backbone groups that are fairly close to each other in the primary sequence C. Tertiary structurei. Final folding of a single protein chain to its globular form ii. Stabilized by interactions between groups on side chains that may be far apart in the primary sequence but close together in the final 3-D shapeD. Quaternary structurei. The non-covalent attraction of 2 or more separate protein chains (subunits) to form a functional unitii. Stabilized by interactions between groups on side chains that may be far apart in the primary sequence but close together in the final 3-D shape E. Lysosome: an enzyme that breaks down bacterial and fungal cell walls F. Surface of a globular protein is covered with organic functional groups that are arranged in a specific 3-D pattern. Each type of protein is different in the details of the arrangements of the functional groups --> non-covalent attraction between macromolecules is responsible for maintaining order and structure in a cell G. Examples of specific attractions between biological macromoleculesi. Regulatory protein binds to a specific sequence of DNA causing a gene to be turned on ii. 2 alpha subunits and 2 beta subunits combine to make a molecule of hemoglobin (the smaller the subunits, the faster they travel)iii. Phospholipids that make up a cell membrane associate with one another to make a sheet-like structureiv. Antibody molecules attach to viral surface proteins v. Molecules of the protein actin stick to each other to form microfibers thatare found in muscle cells vi. Epithelial cells stick to each other to form a tissue layer because of specific surface proteins called


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