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Biologically Important Carbohydrates:
- Monosaccharides
- Disaccharides
- Polysaccharides

Structures and Names:
- Example of Monosaccharides: Basic units with either an aldehyde or ketone group.
- Aldoses: Carbohydrates with an aldehyde as its carbonyl unit.
- Ketoses: Carbohydrates with a ketone as its carbonyl unit.
Open-Chain and Ring Forms:
- Fischer Projections: Represent open-chain structure.
- Haworth Projections: Represent cyclic form.
- Cyclization: Monosaccharides cyclize to form a ring structure due to nucleophilic attack by hydroxyl group on carbonyl carbon, leading to reduction of carbonyl to alcohol.
- Anomeric Carbon: The new chiral center formed during cyclization.
- Configurations:
  - α-anomer: Hydroxyl group trans to the CH₂OH substituent.
  - β-anomer: Hydroxyl group cis to the CH₂OH substituent.

Stereoisomers: Sugars that have the same molecular formula but differ in the spatial arrangement of atoms.
- Enantiomers: Non-superimposable mirror images, differing at all chiral centers.
- D and L Isomers: Designated based on the orientation of the furthest chiral center from the carbonyl.
  - Example: D-glucose and L-glucose are enantiomers but have the same solubility properties.
- Diastereomers: Stereoisomers that are not mirror images.
- Epimers: Special case of diastereomers differing at one specific chiral center.

Examples:
- Ribose: Standard five-carbon sugar.
- Glucose: Standard six-carbon sugar (common in human metabolism).
- Galactose: Epimer of glucose.
- Mannose: Epimer of glucose.
- Fructose: Ketose form of glucose.

Glycosidic Bond: Connects monosaccharides through condensation reaction.
- Formation: Involves the linking of an anomeric carbon with a hydroxyl carbon, resulting in a molecule formed from two sugars.
- Common Disaccharides:
- Lactose: Galactose-β-1,4-glucose.
- Sucrose: Glucose-α-1,2-fructose (nonreducing sugar).
- Maltose: Glucose-α-1,4-glucose.

Types of Polysaccharides:
- Homopolysaccharides: Composed of one type of monosaccharide.
- Heteropolysaccharides: Composed of multiple kinds of monosaccharides.
- Structure: Can be linear or branched.
- Three Major Biological Polysaccharides:
- Cellulose: Polymer of β-D-glucose (1-4 linked), structural component in plants.
- Starch: Mixture of amylose (unbranched) and amylopectin (branched) serving as storage in plants.
- Glycogen: Branched polymer of glucose serving as storage in animals; highly branched with (α1→6) linkers every 8–12 residues.

Examines the role of glycan structures in various biological processes such as cellular structure and signaling.
Glycoconjugates: Combines carbohydrates with proteins/lipids, often involved in cell signaling and recognition.
Glycosylation: The posttranslational modification of proteins via carbohydrate attachment.

Glycoproteins: Proteins with carbohydrate chains.
Functions of Glycoconjugates:
- Cell signaling
- Immune responses
- Cell recognition

The World Health Organization (WHO) and American Heart Association dietary recommendations for added sugars in diets:
- Children: <20g (5-6 tsp) per day
- Women: Max 25g (6 tsp) per day
- Men: Max 36g (9 tbs) per day
Example of Health Impact: Monitoring reducing sugars, like glucose in urine, may indicate diabetes.

Numerical Data:

Average molecular weight of carbohydrates can range from as low as 90 g/mol (glyceraldehyde) to over 200,000,000 g/mol (amylopectin).

Glycosyltransferases: Enzymes responsible for attaching glycans to proteins/lipids, playing a crucial role in forming complex glycoconjugates.
Research Objectives: Focus on identifying glycan structures and their interactions with cancer progression, linkages to disease phenotypes, and cellular communication.

Penicillin: Functions as a β-lactamase inhibitor, targeting bacterial cell wall synthesis via irreversible binding.
Methodologies: Use of liquid chromatography and mass spectrometry for glycoprotein analysis.