Zusammenfassung der Ressource
Carbohydrates
- General
- Most carbs are polymers
- Large, complex molecules composed of long chains of many monomers joined together
- Condensation
- Forms glycosidic bond by the removeal of water
- Hydrolysis
- Breaks glycosidic bond by addition of hydrogen
- Types
- Monosaccharides
- Monomer of one sugar molecule
- E.g. Glucose, Fructose, Galactose
- Disaccharides
- Formed from two monosaccharides joined together
- By condensation reaction to form glycosidic bond
- E.g. Maltose, Sucrose, Lactose
- Sucrose
- Glucose + Fructose
- Lactose
- Glucose + Galactose
- Maltose
- Glucose + Glucose (alpha)
- Polysaccharide
- Made of many monosaccharides joined together
- E.g. Starch, Glycogen, Cellulose, Chitin
- Starch
- Structure
- Combination of two polymers of alpha glucose
- Amylose and Amylopectin
- Amylose
- long unbranched chain
- Angles of glycosidic bonds and h-bonds form coiled structure
- Making it very compact
- Amylopectin
- Long branched chain with side branches
- Function
- Plants only
- Storage molecule in plants
- Insoluble in water
- Doesn't effect water potential
- Doesnt draw in water by osmosis
- Amylose is very compact so can store a lot in one space
- Amylopectin is branched
- Enzymes can attach and breakdown the molecule
- Releases energy quickly
- Test for starch
- Iodine test
- Add iodine to sample
- If starch present the sample changes from brown-orange to blue-black
- Glycogen
- Structure
- Alpha glucose
- Similar to amylopectin in that it is a branched molecule
- Branches are much shorter, more frequent
- and more compact than amylopectin
- Function
- Storage in animal, fungi, bacteria
- Compact storage, lots in one space
- Insoluble, doesnt effect water potential
- More branches that enzymes can attach simutaneously
- For rapid breakdown for glucose molecules used in respiration
- Important for animal cells that are more metabolic active
- Cellulose
- Structure
- Made from monomers of B-glucose
- Causes straight unbranched chains
- Adjacent beta glucose rotate 180 allowing h-bonds to form
- Run parallel and from cross-linkage hydrogen bonds
- Number of h-bonds causes huge strength
- Cellulose chains linked by h-bonds forming microfibrils
- Function
- H-bonds stop water entering, resistant to enzyme hydrolysis
- Makes it good structural support polysaccharide
- Major component in cell walls
- Provides rigidity, prevents cell from bursting
- Only in plants
- Glucose
- Has two isomers
- Alpha and Beta Glucose
- Rotation of functional groups 180 degrees
- Sugars
- Sugars are mono/disaccharides
- Sugars can be reducing or non-reducing
- Reducing test
- Benedicts reagent (blue) to test
- Heat sample to the boil with excess benedicts
- Solid precipitate is positive blue, green, yellow, orange, brick red
- Higher conc of sugar the more colour change
- Comparing concs also weight the precipitate
- All mono and some di are reducing sugars
- Non-reducing
- If benedicts is negative test
- breakdown di to mono
- do this by adding dilute HCl
- Heat to the boil
- Neutralise with NaHCO3
- Then test with benedicts if negative remains blue