Organic Chemistry Essentials

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Questions and Answers

Explain how the properties of the R-group of an amino acid contribute to the overall structure and function of a protein. Provide an example.

The R-group's properties (size, charge, polarity) dictate how the amino acid interacts with other molecules and its location within the protein. For example, hydrophobic R-groups tend to cluster in the protein's interior, away from water.

Describe how a condensation reaction and a hydrolysis reaction are related, yet distinct, in the context of polymer formation and breakdown.

Condensation reactions form polymers by removing water molecules, while hydrolysis reactions break down polymers by adding water. They're opposite processes involved in polymer synthesis and degradation.

Explain how the $\alpha$ and $\beta$ orientations of glucose affect the structure and function of polysaccharides like starch versus cellulose.

$\alpha$ glucose linkages in starch create a helical, loosely packed structure digestible by animals. $\beta$ glucose linkages in cellulose form linear, rigid, tightly packed structures indigestible by animals without specific enzymes.

Describe the role of disulfide bridges in the tertiary structure of proteins, including what amino acid is required.

Disulfide bridges, formed between the sulfur atoms of cysteine residues, covalently link different parts of a protein chain, stabilizing its 3D structure. Signup and view all the answers

Explain why lipids are described as hydrophobic and how this property determines their behavior in an aqueous environment.

Lipids are hydrophobic due to their nonpolar hydrocarbon chains. In an aqueous environment, they cluster together to minimize contact with water, leading to phenomena like the formation of lipid bilayers or micelles. Signup and view all the answers

Describe how the arrangement of phospholipids in a bilayer contributes to the selective permeability of cell membranes.

Phospholipids form a bilayer with hydrophobic tails facing inward and hydrophilic heads facing outward. This arrangement creates a barrier that restricts the passage of polar and charged molecules while allowing nonpolar molecules to pass through more easily. Signup and view all the answers

Explain the difference between a saturated and an unsaturated fatty acid, and how this difference affects the physical properties (e.g., solid vs. liquid at room temperature) of the triglycerides they compose.

Saturated fatty acids have no double bonds, allowing tight packing and resulting in solids at room temperature. Unsaturated fatty acids have double bonds, creating kinks that prevent tight packing and resulting in liquids at room temperature. Signup and view all the answers

Describe how moderate heating can affect the different levels of protein structure, and explain why some levels are more sensitive to heat than others.

Moderate heat primarily disrupts secondary and tertiary structures by breaking hydrogen bonds and hydrophobic interactions. Primary structure (peptide bonds) is more resilient unless heating is extreme. Signup and view all the answers

Describe how the size and shape of glycine and proline affect protein folding and flexibility, and explain why they are often found in specific locations within a folded polypeptide.

Glycine's small size increases flexibility in the protein backbone, often found in loops or turns. Proline's rigid cyclic structure introduces kinks and reduces flexibility, generally disrupting alpha helices. Signup and view all the answers

Explain how environmental conditions such as pH and salt concentration can affect protein structure and function.

Changes in pH and salt concentration can disrupt ionic bonds and hydrogen bonds in proteins, leading to denaturation and loss of function. Extreme conditions can cause irreversible unfolding. Signup and view all the answers

Flashcards

Four main classes of organic molecules

Carbohydrates, lipids (or fats), proteins, and nucleic acids.

Isomer Definition

Isomers are molecules with the same molecular formula but different structural arrangements.