Advanced Botany

Lactose is the main source of sugar from milk and milk products from all mammals except the sea lion. Inadequate lactase activity allows lactose to reach the large intestine. There, the gut flora provides a salvage pathway for lactose digestion by cleaving lactose into short-chain fatty acids and gas, mainly hydrogen (H2), carbon dioxide (CO2), and methane (CH4). Non-digested lactose can cause osmotic diarrhoea; products of its bacterial digestion can lead to secretory diarrhoea and gas distending the intestines, events that are likely to lead to clinical symptoms.  Lactose malabsorption actually refers to inefficient digestion of lactose due to reduced expression or impaired activity of the enzyme lactase. After ingestion, lactose passes into the small intestine where it comes into contact with lactase at the intestinal brush border where it is hydrolysed into the monosaccharides glucose and galactose, which can be readily absorbed. Dis accharide digestion occurs on the brush bord...

  The word 'carbohydrate' was coined more than 100 years ago to describe a large group of compounds include polymers and other compounds synthesized from polyhydroxylated aldehydes and ketones. In general carbohydrates have the empirical formula (CH 2 O) n . They are polyhydroxylated aldehydes or ketones and their derivatives. Chemically, carbohydrates are molecules that are composed of carbon, along with hydrogen and oxygen. The compounds carbohydrates have common same functional groups, glyceraldehydes and gulose are classifed as aldoses and ribulose and dihydroxyacetone as ketoses. All of these compounds are alcohols with many hydroxyl groups. They are polyhydroxylated and either aldehydes or ketones. Classification of carbohydrates Monosaccharides The simplest and smallest unit of the carbohydrates is the monosaccharide, (mono = one, saccharide = sugar). Monosaccharides are either aldehydes or ketones, with one or more hydroxyl groups; the six-carbon monosaccharides g...