Carbohydrates Flashcards
Monosaccharides
- Simplest form of carbohydrates
- One sugar and usually water-soluble, crystalline solids and colourless
- Sweet taste
- (CH2O)n
Eg - Glucose
- Fructose
- Galactose
- Ribose
Forms of glucose
- A glucose - OH
- B glucose - ^OH
Disaccharides
- 2 monosaccharides - condensation reaction
- Glycosidic bond forms
Eg - Maltose - 2 alpha glucose
- Sucrose - glucose + fructose
- Lactose - glucose + galactose
Polysaccharide
- Multiple condensation reactions between monosaccharides
- Glycosidic bonds
- Range in structure - linear to branched
- Large, insoluble molecule - doesn’t diffuse or affect water potential
Eg/
Starch - a glucose molecules - plant storage
Cellulose - b glucose molecules - structure
Glycogen - a glucose - body storage
Benedict’s Test
- Reducing sugars
- Benedicts agent (blue)
- Blue to red/orange - non-reducing present
Chemical formula of glucose
C6H12O6
How is glucose used by organisms
Respiration - anaerobic and aerobic + storage in plants
What is an isomer
- Same chemical formula but a different structural formula
Glycogen
- Glucose is converted into glycogen to stop it transporting around the body
Starch
- Polysaccharide - alpha glucose
- Helix - coils = compact
- Glycosidic bonds
- Plant storage + energy source
- Lack of branches = insoluble in water
- Branched = rapid release of energy - ends digested at the same time
Insoluble starch
Advantages
- Don’t affect water concentration inside cells - don’t swell or shrink
- Don’t move away from storage areas in plant
- Broken down into glucose - transported around the plant + used in respiration = energy
Glycogen
- Polysaccharide - alpha
- Helix - shorter chains than starch
- Many branches = increase solubility
- Animal storage
Branched glycogen
- Soluble - transported from one area to another
- Creates lots of ends for enzyme action = release glucose fast
Cellulose
- Polysaccharide - beta
- Long straight chains
- Hydrogen bonds = strong layers
Cellulose cell walls
- Strongly bonded together by hydrogen bonds
- Strength and support
- Tough layered mesh - keep plants upright + withstand pressure from within the cell
- Cellulose chains = microfibrils
Chitin
- Hard, polysaccharide
- Shells of crustaceans
- Cellulose with one hydroxyl group on each monosaccharide replaced by an acetylamine group = increased hydrgoen bonding between adjacent polymers
Structural isomer
- Atoms are linked in different sequences
Optical isomer
- Atoms are linked in identical ways but are mirror images of each other
Explain how the isomeric structure of carbohydrate may affect its chemical behaviour
- Isomeric structure changes how the monosaccharides bond - changes its role in biology
2 isomers of glucose; alpha and beta, How do they differ from one another?
- They are the exact same but inverted
Describe briefly the process of the condensation reaction for carbohydrates
- H20 is removed
- Disaccharide is produced
Describe briefly the process of the hydrolysis reaction for carbohydrates
- Water added
- Form 2 monosaccharides
