Biochem Oct. 1st

Carbohydrates also called sugars, are one of four major classes of biomolecules.
Monosaccharides: Single carbohydrate units, e.g., glucose.
Polysaccharides: Formed by joining together monosaccharides, similar to how amino acids form polypeptides.

Sorab’s Experience: A student who drinks coffee to stay awake during class discussions about nutrition.
Types of snacks ordered by friends, raising questions about healthiness versus calorie content.
- Doughnut vs. Muffin: Common misconception about healthier options. Nutrition labels may be misleading.

Carbohydrates are measured in grams, typically provided on food labels, broken down into sugars and fibers.
- Example of a muffin: may state 60 grams of carbohydrates, but breakdown does not always equal the total (hidden ingredients may be included).

Monosaccharides can be characterized by their chemical structure:
- Pentose: 5 carbon atoms.
- Hexose: 6 carbon atoms.
Classification by functional groups:
- Aldose: Contains an aldehyde group.
- Ketose: Contains a ketone group.
- D and L Isomers: Stereochemistry based on the position of the hydroxyl group on the highest-numbered chiral carbon.
- D-sugar: Hydroxyl group on the right.
- L-sugar: Hydroxyl group on the left.

Fischer Projection: A two-dimensional representation used for sugars, established by Emil Fischer (Nobel Prize winner, 1902).
- Important in determining stereochemistry of sugars and representing their structure.
Characteristics:
- Aldose configuration - carbonyl group at the end (C=O).
- Drawing indicates substituent positions and stereochemistry.
Meme Example: Comparing L and D sugars to Samuel L. Jackson meme (visual representation of mirror images).

Sugars like glucose tend to cyclize due to nucleophilic attack (O from fifth carbon attacks carbonyl).
Results in a stable ring structure typically containing 5 or 6 members (favorably cyclized form).
Equilibrium Process: Glucose exists in equilibrium between linear chain and cyclic form.

Hayworth Projection: Simplified representation of cyclic sugars created by Percy Hayworth (Nobel Prize 1937).
Rings are drawn in a way to avoid long bonds, making organic structures cleaner.
Relation between Fischer and Hayworth projections useful for interconverting between the two forms.
- Key formulas indicate the stereochemistry of the corresponding sugar.

Identification of the anomeric carbon (carbon with two bonds to oxygen) is crucial for defining alpha (a) and beta (b) forms of sugars.
- Alpha glucose: Hydroxyl on the opposite side of the anomeric carbon.
- Beta glucose: Hydroxyl on the same side as the anomeric carbon.
Common mnemonic: Vowels (alpha/opposite) and consonants (beta/same).
Both forms are interconvertible in a reaction termed mutarotation.

-Disaccharides: Formed when two monosaccharides bond through a glycosidic bond via a condensation reaction.

Example: Lactose (from beta-galactose and glucose) created through a one-four linkage.
- Involves an O glycosidic bond formation.

Disaccharide formed from glucose and fructose (table sugar).
- Key structural characteristics noted in both Fischer and Hayworth forms.
Identification of the anomeric carbon evident in the structure of both components needed to determine binding characteristics and resulting properties.

Questions and activities to engage students on differentiating between structures:
- Identifying anomeric carbons, recognizing differences in alpha and beta sugars, and determining the correct Fischer/Hayworth representation.
- Engage in peer discussion to reinforce understanding.

Connects the study of sugars to their biochemical significance in nutrition, metabolism, and practical food sciences.
Through clear examples and representations, students are prepared for assessments regarding structure and function of carbohydrates in biological contexts.