Biological molecules Flashcards
Explain the role that water plays (8 points)
1) SOLVENT-water is POLAR- means it can dissolve any charged molecules e.g like sodium ions and any other POLAR molecules
2) HIGH SPECIFIC HEAT CAPACITY-A lot of energy is needed to raise water up by 1 degree and ir cools it slowly.- stabilises aquatic habitats and acts as a buffer for changes of temperature
3) LATENT HEAT OF VAPORISATION-due to hydrogen bonds it takes a lot of energy to evaporate it-having a cooling effect with a small vol of water
4) LESS DENSE- when water is frozen/ice it rises to the top allows for insulation for the fish
5) TRANSPARENT-plants can photosynthesise as light can go through water
7) METABOLITE- can hydrolyse reactions, its a chemical that can be USED AND PRODUCED in reactions
8) SURFACE TENSION- water is COHESIVE so therefore it creates surface tension and small organisms can utilise
Define polymer and monomer
monomer- small,single, soluble subunit that can bond together to form a polymer
Polymer- large,insoluble chain of many repeating units bonded together
what is the empirical formula for carbohydrates and role of carbohydrates
empirical formula; CH2O(n) where n = the number of carbon atoms role of carbohydrates; monosaccharides -to provide energy/ ATP -building blocks of polysaccharides -building RNA/DNA nucleotides polysaccharides; - starch/ glycogen act as energy stores in plants/animals -cellulose makes up plant cell wall
write out the benedict test for reducing sugars
- add 2cm3 of benedict solution to the food sample
- place test tube in water bath (90 degrees) for 5 min
- If colour turns from blue to brick red means there is a reducing sugar present
(can also turn green orange)
Name 3 common disaccharides and the monosaccharides that make them.
Maltose= a glucose + a glucose (reducing) Sucrose= a glucose + fructose (non-reducing) Lactose= glucose + galactose(reducing)
Write out the the food test for non-reducing sugars
- state try benedict’s test before and if it stays blue then you :
1. BOIL WITH hydrochloric acid to break the glycosidic bond
2. add an ALKALI to neutralise to solution
3. add 2cm3 of benedict solution
4. place in a 90 degree water bath for 5 min
5. if there is a colour change means reducing sugar is present
How does starch form
MANY a glucose bind by condensation reactions by a C1-C4 glycosidic bond, causes the starch to be tightly coil up
(insoluble polysaccharide)
Explain the role of starch
1) used as an energy store
2) starch contains a lot of AMYLOSE
- AMYLOSE is compact and therefore can store a lot of energy in a small space
- It is INSOLUBLE so it doesn’t effect water potential and CANNOT diffuse out of cells.
- HYDROLYSIS of starch releases glucose for use in RESPIRATION to make ATP.
What are the similarities between starch (amylose) and glycogen?
- both contain glucose therefore have glycosidic bonds
- both store of energy for respiration/ATP
- both are insoluble- so they don’t effect water potential
- both are coiled to store as much energy in a small space
What are the differences between starch (amylose) and glycogen?
- Glycogen is in animals and Starch is in plants
- Glycogen has a C1-C4 and C1-C6 glycosidic bond whereas starch has only a C1-C4 glycosidic bond
- Amylose is not branched whereas glycogen is heavily branched
- Glycogen has more terminal ends to allow quick hydrolysis for the release of glucose, but amylose doesn’t as its unbranched
explain the food test for lipids
add 2cm3 of ETHANOL to the food sample then shake for a few mins
THEN ADD 2cm3 of WATER and shake
if solution turns milky/white then it means lipids are present and emulsion has taken place
Write out the food test for starch.
add 2cm3 of POTASSIUM IODIDE/ iodine to the food sample
if colour changes from orange to dark blue/black means starch is present
Detail the formation of cellulose
- beta glucose bind by glycosidic bonds
-every beta glucose is flipped/ turned 180 degrees creating a condensation reaction between C1-C4 glycosidic bond
-forms a straight unbranched polysaccharide as the multiple strands/polysaccharides are bonded with HYDROGEN BONDS - forming MICROFIBRILS
and MANY MICROFIBRILS combine to make macro fibrils
Microfibres combine to form cellulose.
what is the function of Cellulose in plant cell walls
its a Fibrous polysaccharide.
The function is to withstand the OSMOTIC FORCES/PRESSURE when cells become TURGID
also provides structure to the plant and cell
What are the roles of lipids
1) insulation
2) protection
3) waterproof e.g waxy cuticle of leaves
4) source of energy for producing ATP in respiration
5) production of phospholipids that make up the cell surface membrane
