Carbohydrates + Lipids Flashcards
Chemical formula for alpha glucose
C6H12O6
Maltose structure
Glucose + Glucose
Sucrose structure
Glucose + Fructose
Lactose
Glucose + Galactose
Enzyme suffix
-ase
What 2 subcategories are carbohydrates divided into?
Sugars (mono +di)
Polysaccharides (storage + structural)
Name 2 storage polysaccharides
Starch (plants)
- AmylOse
- Amylopectin
Glycogen (humans)
Name a structural polysaccharide
Cellulose (beta-glucose)
Describe amylOse structure (STARCH)
- Long straight chains of alpha glucose
- COil into a helix (amylOse)
- Compact so good for storage
- Insoluble so doesn’t affect water potential
- Large so cannot diffuse out of cell
Describe amylopectin structure (STARCH)
BRANCHED chain of alpha glucose
- Large surface area for rapid hydrolysis by enzymes (to release glucose for respiration)
- Insoluble so doesn’t affect water potential
- Large so cannot diffuse out of cells
Describe glycogen structure
Similar to starch, however:
- Shorter chains
- More highly branched
- Larger surface area
Explain advantage of glycogen being more highly branched
Glycogen hydrolysed more rapidly into glucose to be used in respiration (as animals require glucose faster than plants can hydrolyse starch)
Describe cellulose structure
- Long straight unbranched chains of beta-glucose
- Every other beta-glucose molecule inverts 180 degrees to form 1-4 glycosidic bond.
- Several chains joined together in layers by MANY WEAK h-bonds to form micro/macrofibrils
What is cellulose found in?
Plant cell wall
Starch use and location
Storage and plant
Glycogen use and location
Storage and animal
Cellulose use and location
Structure and plant
The structure of cellulose is related to its role in plant cell walls. Explain how (3)
- Long straight chains of beta-glucose
- Joined by many weak hydrogen bonds
- To form micro/macrofibrils
- To provide integrity/rigidity
Hydrogen bonds are important in cellulose molecules. Explain why (3)
- Join cellulose chains together to form micro/macrofibrils
- Providing rigidity/integrity to cell wall
- Weak bonds provide strength in larger numbers`
Describe benedicts test for reducing suagr
- Add equal volume of benedicts reagent to solution
- Heat to 95 celcius
- Red precipitate indicates sugar present
Describe how a student would show that a non-reducing sugar was present in a solution (6)
- Complete benedicts test and observe negative result (blue precipitate)
- Add acid (HCL) to solution AND heat to 95 celcius
- Neutralise with alkali
- Add equal volume of benedicts reagent
- Heat again to 95 celcius
- Observe red precipitate formed as reducing sugar is now present
What is an arbitary unit?
A scale of measurement to show the ratio of amount of substance to a predetermined reference measurement
Describe how you would produce a calibration curve for a reducing sugar of unknown concentration and use it to obtain results (5)
- Make up several known concentrations of glucose
- Perform benedicts test on each sample
- Use colorimeter to measure colour intensity of each solution AND plot calibration curve
- Plot known conc. on X-axis and aborbance on Y-axis
- Find concentration of unknown sample using calibration curve
Describe how you would test a food sample for starch
- Add potassium iodide solution to food sample
- Turns purple in presence of starch
