University:
Cameron University
Course:
1004 | General Biology
Academic year:

2019
Views:

143

Pages:

1
Author:

Clint W.

CARBOHyDRATES Monosaccharides Polysaccharides The monomer of a carbohydrate is called a monosaccharide • Monosaccharides primarily function as an energy source Monosaccharides are covalently joined by glycosidic linkages to form polymers (requires condensation reactions) Examples of monosaccharides include glucose and ribose Monosaccharides may be joined into disaccharides for ease of transport, or may form more complex polysaccharides CH2OH HOCH2 O OH O OH OH HO OH OH Glucose OH Ribose Polysaccharides may be used for a variety of cell functions: • Short term energy storage (e.g. glycogen, starch) • Structural components (e.g. cellulose) • Recognition / receptors (e.g. glycoproteins) The carbohydrate formed depends on the monosaccharide subunits used and the bonding arrangement between them Types of Polysaccharides Cellulose (component of plant cell wall) • Linear molecule made of β-glucose subunits • Subunits bound in a 1-4 arrangement Starch (energy storage in plants) • Composed of α-glucose subunits and exists in two forms • Amylose is linear (helical) and bound in 1-4 arrangements • Amylopectin is branched (bound in 1-4 and 1-6 arrangements) Cellulose Amylose Glycogen Amylopectin Glycogen (energy storage in animals) • Branched molecule composed of α-glucose subunits • Is like amylopectin but with more frequent 1-6 bonding Energy Storage Body Mass Index Carbohydrates and lipids are both used as energy storage molecules, however they differ in certain key aspects: • Storage (lipids used for long term storage) • Osmotic pressure (lipids easier to store) • Digestion (carbohydrates easier to utilise) • ATP yield (lipids store more energy per gram) • Solubility (lipids insoluble / harder to transport) While carbohydrates (and lipids) are important components of a healthy diet, excess intake can affect body mass Lipid Storage Short term Long term Osmolality More effect Less effect Digestion Easier to digest Harder to digest ATP Yield Smaller Larger (~2×) Solubility Soluble (mono-/dimer) Insoluble in water BMI can be calculated with an alignment chart (nomogram) 150 Weight (kilograms) Carbohydrate The body mass index (BMI) can be calculated as follows: • BMI = Mass in kg ÷ (Height in m)2 Obese 130 110 al Nor m 90 70 50 Underweight 1.5 1.6 1.7 1.8 1.9 Height (metres) 2.0 2.1 2.2