Carbohydrates Overview

Carbohydrates

• Carbohydrates are the body's primary fuel source
• They range from small sugar molecules (monosaccharides) to large polysaccharides
• Monosaccharides contain hydroxyl groups and a carbonyl group
• Many sugars end with the suffix "-ose"
• Common monosaccharides include glucose and fructose
• Most monosaccharides form rings in aqueous solutions
• Polysaccharides are formed through dehydration reactions
• Examples of disaccharides include maltose (glucose + glucose), sucrose (glucose + fructose)
• Sucrose is a common energy source for plants
• Polysaccharides are long chains of sugar units, including starch, glycogen, and cellulose.
• Starch is stored in plants, glycogen in animals, and cellulose in plant cell walls.
• Plants store glucose as starch, and animals store glucose as glycogen.
• Cellulose is the most abundant organic compound on Earth, with glucose monomers joined differently than starch and glycogen. Its parallel strands create hydrogen bonds for structural integrity.
• Many animals can't digest cellulose
• Cellulose's structure makes it insoluble fiber
• Pandas's diet is primarily cellulose in bamboo shoots.

Lipids

• Lipids are hydrophobic (water-fearing) molecules composed largely of carbon and hydrogen.
• Fats (triglycerides) consist of glycerol linked to three fatty acids via dehydration
• Lipids typically end in "-ol"
• Some fatty acids contain double bonds, forming unsaturated fatty acids. Plant oils typically have unsaturated fatty acids.
• Saturated fatty acids have the maximum number of hydrogens and are typically found in animal fats. Their structure allows them to be packed tightly, making them solid at room temperature.
• Unsaturated fatty acids have fewer hydrogens and are typically found in plant oils. They have kinks in their structure and are liquid at room temperature.
• Partially hydrogenated oils are created by adding hydrogens to unsaturated fats, and sometimes make trans fats, which can increase the risk of heart disease.
• Phospholipids are major components of cell membranes, being amphipathic with a hydrophobic tail and a hydrophilic head.
• Steroids are ring-containing lipids.
• Cholesterol is the most common steroid and is a precursor to other steroids, including sex hormones.
• Cholesterol affects cell membrane fluidity. Insertion of cholesterol into cell membranes decreases fluidity.
• Red blood cells (RBCs) contain hemoglobin, which carries oxygen. Increased cholesterol in RBC membranes can decrease motility, reducing oxygen transport.

Additional Notes

• Soaps are amphipathic, cleaning by binding to both water and oil/fat.