Biochemistry Lecture: Carbohydrates

Study Notes

Introduction to Carbohydrates

Carbohydrates are polyhydroxyaldehydes or polyhydroxyketones, yielding these components upon hydrolysis.
Commonly referred to as saccharides or sugars, they consist of carbon, hydrogen, and oxygen, with occasional nitrogen.
General formula: Cn(H2O)m, indicating a structure similar to water molecules.
They serve as a main energy source, particularly glucose, and act as chemical energy storage in glycogen (animals) and starch (plants).

Classification of Carbohydrates

Classified based on the number of carbon atoms, functional groups, polymerization, optical rotation, anomers, sugar units, glycosidic linkage, and reducing properties.
Major categories include monosaccharides, disaccharides, and polysaccharides.

Monosaccharides

Basic building blocks of carbohydrates that cannot be hydrolyzed further.
Generally sweet, soluble in water, and typically end with the suffix '-ose'.
Examples: glucose, ribulose, and maltose.

Functional Group Classification

Aldoses contain aldehyde groups; examples include glyceraldehyde.
Ketoses contain ketone groups; examples include dihydroxyacetone.
Both aldoses and ketoses are constitutional isomers with the formula C3H6O3.

Carbon Atom Classification

Carbohydrates categorized as trioses, tetroses, pentoses, and hexoses based on carbon atom count.
Examples:
- Trioses: glyceraldehyde, dihydroxyacetone
- Pentoses: ribose, arabinose
- Hexoses: glucose, fructose

Structural Representations

Fischer Projections represent the open-chain form and D/L conformation of carbohydrates.
Haworth Projections depict the cyclic chain form and α/β conformation of carbohydrates.
Optical rotation and anomers are essential features in these representations.

Glycemic Index and Carbohydrate Sources

Glycemic index categorizes foods based on their effect on blood sugar levels.
'Good' carbohydrates have a low glycemic index and are high in fiber, while 'bad' carbohydrates have a high glycemic index and are often processed.
Carbohydrates are essential macronutrients needed for proper bodily functions, sourced from both healthy (animal and plant) and unhealthy (processed foods, artificial sugars) origins.

Description

Explore the classification of carbohydrates in this biochemistry lecture. The quiz covers the different categories, chemical formulas, and structures that define carbohydrates. Perfect for students in the BSPSYA program looking to deepen their understanding of this essential biomolecule.