Carbohydrate Chemistry Quiz

Carbohydrates Overview

• Carbohydrates are a group of carbonyl compounds (aldehydes or ketones) that also contain several hydroxyl groups.
• The general formula for carbohydrates is (CH₂O)ₙ.
• Carbohydrates can be classified by the number of monomers: monosaccharides, disaccharides, oligosaccharides, polysaccharides.

Carbohydrate Objectives

• Recognize the general structure of carbohydrates.
• Classify carbohydrates.
• Recognize disaccharides.
• Recognize polysaccharides.
• Explain carbohydrate-modified protein structures and their functions.
• Explain the digestion of carbohydrates.

Carbohydrate Structure and Classification

• Key components include carbonyl groups (aldehydes or ketones) and hydroxyl groups.
• Aldoses have an aldehyde group at the end of the carbon chain.
• Ketoses have a ketone group within the carbon chain.
• The number of carbons categorized carbohydrates as trioses, tetroses, pentoses, hexoses, heptoses, and nonoses, among others.
• Isomers have the same chemical formula but different structures.

Monosaccharides

• The simplest carbohydrates.
• Examples include glucose, fructose, and galactose.
• Important for energy and building blocks.
• Can exist in linear or ring forms.
• The presence of an aldehyde or ketone group is important for their role.
• Classified as aldoses or ketoses based on the functional group.
• Specific types of carbohydrates have specific roles based on the placement of oxygen and/or hydroxyl groups.

Disaccharides

• Two monosaccharides joined together.
• Examples include sucrose, lactose, and maltose.
• Joined by a glycosidic bond.
• Glycosidic bonds are crucial for joining molecules.

Polysaccharides

• Many monosaccharides linked together to form long chains.
• Examples include glycogen, starch, and cellulose.
• Glycogen and starch are energy storage molecules.
• Cellulose is a structural component in plant cell walls.
• They have different structures, which determine their function; (i.e., linear or branched).

Protein-Carbohydrate Structures

• Carbohydrates can combine with proteins to form glycoproteins and proteoglycans.
• Glycans are short sugar chains.
• A proteoglycan is a protein and a carbohydrate.
• Glycosylation is a common post-translational protein modification where sugar chains are added to the protein after formation in the cell.
• Many molecules have glycoproteins.
• Glycoproteins are often found on the cell surface.

Digestion of Carbohydrates

• Enzymes break down glycosidic bonds.
• Different enzymes are needed for different types of glycosidic bonds.
• Carbohydrates are broken down into smaller components during digestion to be absorbed into the body.
• Humans cannot digest cellulose, but some microorganisms can.

Absorption of Monosaccharides

• Monosaccharides are absorbed by cells in the small intestine.
• Specific transport proteins (e.g., SGLT-1, GLUT-5).
• Blood glucose levels are carefully regulated.
• Glucose is crucial for energy and brain function.

Other important notes:

• Different types of carbohydrates have different roles in the body, from energy storage to structural support.
• The structure of carbohydrate molecules significantly affects their function.
• Understanding carbohydrate digestion and absorption is key for maintaining blood glucose homeostasis.