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Test for reducing sugars
Benedict’s/CuSO4
2cm3 of sample + 2cm3 Benedict’s
Heat gently in water bath for 5 mins
Blue to orange
Maltose
Glucose + Glucose
Sucrose
Glucose + fructose
Lactose
Glucose + galactose
Test for non-reducing sugars
Benedict’s/CuSO4:
Same as reducing- if stays blue=reducing not present
2cm3 more sample to 2cm3 dil HCl in water bath for 5 mins (hydrolyses dissacharides)
Slowly NaHCO3 to neutralise (reagent doesn’t work in acidity)
Repeat reducing test
Test for starch
Iodine/KI:
sample to test tube/spotting tile
2 drops iodine + shake/stir
Yellow to blue-black
Starch features
Amylose (S) vs Amylopectin (B)
Only in plant cells
Feature | Benefit |
|---|---|
Insoluble | Osmosis not affected |
Large | no diffusion out cells |
Compact/coiled | More in small vol |
a-glucose | easy to transport + respiration |
branched amylopectin | more ends for enzymes=faster hydrolysis |
Glycogen features
Not in plants
Feature | Benefit |
|---|---|
Insoluble | Osmosis not affected No diffusion out cells |
Compact/coiled | More in small vol |
More branches than starch | Hydrolysis faster for high metabolic rate/respiration |
Cellulose
Feature | Benefit |
|---|---|
Straight, unbranched, parallel | H bonds form cross-linkages between chains |
Exerts inward pressure | prevent further influx H2O |
Form microfibrils | More H bonds (180o) for turgidity= max SA for photosynthesis in leaves/stems |
a-glucose structure
DDUD
b-glucose structure
UDUD
Why are triglycerides good storage molecules?
low mass: energy, so more stored in low vol.
high ratio of C-H bonds
Release H2O when oxidised for dry environments
Lipid test
2 sample : 5 ethanol
Water + shake
Milky white ppt
Control for lipid test?
Repeat emulsion test w/water instead of sample- soln =clear
Protein test
Biu
Induced fit
S close to E, forming complementary active site
Shape change puts strain on S, distorting bonds in S, lowers Ea
conditions for cell fractionation
cold: reduce E activity on organelles
buffer: pH can affect organelle structure/enzymes
isotonic: no bursting/shrinking
Homogenation
blend to break the cells to release the organelles
Ultracentrifugation
Filtrate spun at slow speed
Heavier organelles form sediment/pellet at bottom
Fluid at top/supernatant removed
Supernatant in new tube+repeat
TEM (2D) limitations
e- beam could destroy specimen
dead, pre-prepared, thin specimen
complex staining but in B+W
SEM (3D)
not extremely thin needed
BUT lower resolution than TEM
Purpose of cristae in mitochondria
large SA for E + protein attachment in respiration
Endoplasmic reticulum
Smooth | Rough |
|---|---|
no ribosomes | ribosomes |
Large SA for protein+glycoprotein synthesis | Synthesise, store, transport lipids, carbohydrates |
Provide pathway for transport |
Golgi apparatus
Cisternae= flattened sacks
make vesicles
modify, repackage
Prophase
Chromosomes thicken
centrioles make spindle fibres, attach to centromere
nuclear envelope gone
cholesterol
hydrophobic, limiting movement of molecules
less fluid at high temps
no H2O leakage
antibody structure
2 antigen BS, light chains, heavy chains, disulfide bridges, receptor BS
Note 
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