Carbohydrates Flashcards
What are the elements found in carbohydrates
Carbon, hydrogen, oxygen
What are the 3 reason that carbohydrates are important
They are a source of short term energy for a cell
They are the main reactant in cellular respiration
They are necessary to build biological molecules.
What are the functional groups in carbohydrates
carbonyl and hyrdoxyl
Functions of carbohydrates
Source of energy
Building materials
Cell surface markers for cell to cell identification and communication
Monosaccharides
Made up of 1 simple sugar. Most common is glucose others include galactose and fructose. Glucose is produced during photosynthesis, galactose is in milk and fructose is in fruits.
What process produces majority of carbohydrates
Photosynthesis
Draw glucose, fructose and galactose
Difference between glucose and galactose
Different shapes
Different physical and chemical properties
Isomers
Same chemical formula but different arrangement of atoms.
2 forms of glucose
alpha glucose where the 1 oh group on carbon points downwards and beta glucose where 1 oh group point upwards
ribose
a 5 carbon sugar(pentose) found in DNA and RNA
Fructose is a type ribose
2 types of ribose
Ribose- OH group on C2
Deoxyribose- missing oxygen on C2
Disaccharide
Made of 2 monosaccharides and are joined by a glycosidic link and all have 1 glucose
Example of disaccharides
Maltose- glucose +glucose (grains)
Sucrose- glucose+fructose (table sugar
Lactose- glucose+galactose (milk)
Condensation/ dehydration synthesis reaction
When two monosaccharides combine, there is a loss of an OH from one molecule and an H from another molecule, which together form H2O as a byproduct.
The resulting bond is called a glycosidic linkage. Anabolic (forming complex molecules)
Polysaccharides
Complex carbohydrates
Hundreds of glucose molecules formed by glycosidic bonds
Functions of Polysaccharides
Energy storage(animals) and structural support(plants). (insoluble in water)
Energy storage of polysaccharides
Starch-
Glycogen-polymer of alpha glucose in animals (stored in liver if excess)
Structural polysaccharides
Chitin- Modified glucose units containing functional groups in insect exoskeleton. found in fungal cells
Cellulose-polymer of beta glucose in plant cell walls
Starch
- polymer of alpha glucose in plants (skeleton for plants)
- mixture of 2 polysaccharides
- amalyose which is unbranched(consists entirely of monomers connected by 1-4 glycosidic linkages )
- amylopectin branched ( consists of mostly 1-4 linkages, but some periodic 1-6 which gives it a branching effect )
- Insoluble
-Excess glucose is stored in the form of starch in plants
Glycogen
-stored in liver and muscle cells.
-Whenever blood glucose levels decrease, glycogen is broken down (via hydrolysis) to release glucose monomers that cells can absorb and use.
Α-1,4-link glycosidic
Cellulose
- Polymer of β-glucose
- β 1,4 link (alternating bond orientation)
- H-bonds between cellulose molecules form bundles with high tensile strength
Why can’t we digest cellulose
-The chains of polysaccharides cluster together to form parallel bundles that are held together by hydrogen bonds between hydroxyl groups
- makes them extra strong so they can’t be broken by human digestive enzymes.
Chitin
- made out of modified glucose units that bear a nitrogen-containing functional group
- the hard exoskeleton of arthropods is made of chitin
- found in the cell walls of fungi
Similar to cellulose
