Organic Molecules Flashcards
Water is a dipole, why does this make it useful as a solvent?
Attracted to other positive molecules (ions)
Attracted to other polar molecules (glucose)
These dissolve in water
Chemical reactions take place in solution.
How is water useful as a solvent?
Transport Medium
In what reactions is water used as a metabolite?
Condensation
Photosynthesis
Hydrolysis
Which is beneficial for water to have a high specific heat capacity?
Prevent large fluctuations of water temp
Keeps aquatic habitats stable
Enzymes work efficiently
Why is beneficial for water to have a high latent heat of vaporisation?
Temperatur Control
Heat is used to vaporise water for a leafs surface or sweat on the skin.
How does cohesion work in water molecules?
H bonds between molecules, many bonds make molecules stick together.
Allows columns of water to be drawn of xylem vessels in plants.
Why is it beneficial for water to have high surface tension?
Cohesion between water molecules at surface of pond produces surface tension
Body of an insect is supported.
Why is beneficial for water to have a high density?
Provides support and buoyancy for aquatic organisms
Ice is less dense than water, why is this important?
Ice floats on water
Ice is a good insulator and prevents large bodies of water losing heat and freezing
Organisms can survive below it.
Water is transparent, why is this important?
Light can pass through, aquatic plants can photosynthesise.
Chemical formula for monosaccharides
(CH2O)n
Functions of monosaccharides
- source of energy in respiration
- build larger molecules
- intermediates in reactions
- constituents of nucleotides
How is a disaccharide formed?
Condensation reaction
How is a glycosidic bond broken?
Hydrolysis reaction
What component monosaccharides make up these disaccharides?
Maltose
Sucrose
Lactose
Maltose: glucose+ fructose
Sucrose: glucose + fructose
Lactose: glucose+ galactose
How do you test for the presence of sugars?
Benedict’s test:
- equal volumes of benedicts reagent and solution are heated to at least 70
- reducing sugar= solution turns from blue to brick red precipitate
How do you detect non reducing sugars?
Heated with hydrochloride can acid to break down into monosaccharides
Alkaline added( reagents need alkaline to work)
Benedicts reagent added and heated.
Why is glucose converted to starch?
- insoluble = no osmotic effect
- cannot diffuse out of cell
- compact molecule- can be stored in small spaces
- carries a lot of energy in bonds
What are the two polymers of starch?
Amylose
Amylopectin
Describe amylose
- linear, unbranched molecule
- a-1,4 glyscosidic bonds
- forms a chain that coils into a a-helix
Describe amylopectin
Chains of glucose monomers with a-1,4 glycosidic bonds
Cross linked with a-1,6 glycosidic bonds and fit inside the amylose.
What is the test for the presence of starch?
Iodide test:
Iodine solution reacts with starch, resulting in a colour change from orange- brown to blue-black.
Describe glycogen
Main storage product in animals
Similar to amylopectin:
Shorter a-1,4 linked chains - more branched.
Describe structure of cellulose
Long parallel chains of b-glucose units
-joined by b-1,4 glycosidic bonds
( links rotate by 180)
H bonds form between parallel chains- stability
60-70 molecules become tightly crossed to form microfibrils
Held in bundles called fibres
