Carbohydrates and Sugars PDF

Carbohydrates and Sugars  Carbohydrates- are a major source of energy from our diet.  Composed of the elements C, H, and O  Also called saccharides Main functions: → Main source of energy for all living organisms → Structural support → Act as “road markers” --- sign...

Carbohydrates and Sugars  Carbohydrates- are a major source of energy from our diet.  Composed of the elements C, H, and O  Also called saccharides Main functions: → Main source of energy for all living organisms → Structural support → Act as “road markers” --- signal o Cell markers are carbohydrate chains on the surface of cells where they act as “road signs” allowing molecules to distinguish one cell from another → Can be represented by the stoichiometry formula  They can exist as linear chains or as ring-shaped (CH2O), where n is the number of carbons in the molecules. molecule.  In aqueous solution, they are usually found in ring → The ratio of carbo to hydrogen to oxygen is 1:2:1 form.  α solution: if the OH group is in carbon number 1  β solution: if the OH group is above the plane. Carbohydrates as Structural Support Classifications (differences) of CARBOHYDRATES: Types of Monosaccharides: GLUCOSE Monosaccharides  Glucose is an alpha-carbohydrates (α-  The simplest carbohydrates carbohydrates)  Cannot be broken down to smaller carbohydrates  Dextrose or blood sugar  One sugar unit  Primary fuel for the body  Pinagmumulan ng lahat ng carbohydrates  Not commonly found in diet but can be produced by  Important single sugar are: breaking down complex structures with the help of o Glucose enzymes. o Fructose o Galactose  The number of carbons usually ranges from 3 to 7.  Most monosaccharide name and with the suffix –ose  If the sugar has an aldehyde group, then it is named as aldose  If the sugar has a ketone group, it is known as ketose  Depending on the number of carbons in the sugar, they also may be known as trioses, pentose, and/or hexoses.  Oligosaccharides  Type of carbohydrate formed when 3 to 10 simple FRUTOSE sugars are linked together  Short chain or monosaccharides  Are classified as β-carbohydrates  Small amounts occur naturally in many plants  Sugar of fruit, honey  Can have many functions including cell recognition  Sweetest of all simple sugar  Usually present in soft drink, ready to use cereals and cell binding and deserts  Converts to glucose in the body GALACTOSE  Are classified as β-carbohydrates  found combines with glucose in the disaccharide lactose present in milk  They are known as milk sugar Polysaccharides  Are large molecules of monosaccharides that are Disaccharides connected to each other through their anomeric  Consists of two monosaccharide units that are joined carbons together.  Classifications: o Contain only single monosaccharide (can  They can be split into two monosaccharides be branched or unbranched) o Maltose= glucose + glucose o Lactose= glucose + galactose o Contain two or more monosaccharide (can be branched or unbranched) o Sucrose= glucose + fructose  Formation of covalent bonds which are known as glycosidic bonds.  It can be alpha or beta bond  Types: o α bond- formed when OH group on carbon o Storage polysaccharides- contain only α- 1 of the first glucose is below the ring glucose units (starch, glycogen, and plane. amylopectin) o β bond- formed when the OH group on the o Structural polysaccharides- contain only β- carbon 1 above the ring plane. glucose unit (cellulose and chitin) Starch- can be branched or unbranched If starch is unbranched then it is,  Amylose o Makes up 20% of plant starch o Long chains of amylose tend to coil  o Can be found in plant foods If starch is branched, then it is,  Amylopectin o Makes up 80% of plant starch o More complicated structure Sources of Carbohydrates glucose Fruits, honey, corn syrup fructose Fruits, honey Glycogen galactose milk + Can be similar in structure with starch maltose Backed starched + Storage form of polysaccharide found in sucrose Cane & beat sugar animals lactose Milk products + When glucose is needed, glycogen is Starch & dextrin Grains, root & tubers, hydrolyzed in the liver to glucose legumes glycogen Meat product, sea food cellulose Vegetables. Outer coat of seed Pectin & gum Fruits, plant secretion, seeds DIGESTION AND ABSORPOTION OF CARBOHYDRATES Digestion in Mouth  Mechanical Digestion o Chewing crumble known as mastication, crumble the carbohydrate food into smaller and smaller pieces forming bolus.  Chemical Digestion o Salivary glands in oral cavity secrets saliva o Starch -> maltose o Only 5% of starch are broken down in mouth Digestion in Stomach  Mechanical Digestion Cellulose o Peristalsis  Chemical Digestion + Contains glucose unit bonded o Action of ptyalin continues only inside bolus + The chain of glucose units is straight; this o About 30-40% of dietary starch is allow chains to align next to each other to digested before bolus is broken down and form a strong rigid structure acidified o Enzymatic reaction stops when chyme is passed down to the small intestine Digestion in Small Intestine  Mechanical Digestion o These is no mechanical digestion  Chemical Digestion o Action of pancreas o Pancreatic juice o Absorption Intestinal Enzymes Undigested Carbohydrates  Certain carbohydrate like cellulose is undigested by human due to lack of enzymes like cellulase  However, it provides fibers for absorption of water into the large intestine which expand the muscle walls and trigger muscle contraction for egestion. Glucose when needed, are transported in most cells through: Excess intake of Carbohydrates: ✓ Places a large metabolic load on the body which leads to weight gain, poor metabolic health and increased risk of heart disease ✓ Consuming too many carbs especially those with a high glycemic load, can increase the risk of several disorders, including type II diabetes ✓ Diet containing too many carbs can also raise fat that travels in the blood leading to cardiovascular disease. Low intake of Carbohydrates: ✓ Long-term restriction of carbs in the diet may lead to kidney damage, increased risk of cancer, impairment of physical activity and lipid abnormalities