Biological Molecules Flashcards
(54 cards)
What are the properties of water
Liquid
Density
Solvent
Cohesion and surface tension
High specific heat capacity
High latent heat of vaporisation
Reactants
Carbohydrates
Contain only hydrogen, carbon and oxygen
Are long chains of sugar molecules
Acts as a source of energy , store of energy , structural unit
Monosaccharides, disaccharides, polysaccharides
Monosaccharides
Simplest carbohydrates
Can exist as a straight chain or ring or cyclic form
Backbone of single bonded carbon atoms with one double-bonded oxygen atom to form of carbonyl group
the monomers of more complex carbohydrates, and they bond together to form disaccharides or polysaccharides.
Disaccharide
They can either be a reducing (maltose and lactose) or a non reducing sugar (non reducing sugar)
Form when two monosaccharides join together
Condensation reactions
Form glycosidic bonds
Two hydroxyl groups line up next to each
other, from which a water molecule is removed
This leaves an oxygen atom acting as a link between the two monosaccharide units.
are sweet , soluble, crystallisable
Glucose
Alpha - C1 has the H on top
Beta has the H on bottom
C6H12O6
Energy source
In glycogen and starch energy store - alpha
In cellulose-beta
Hexose
water liquid function
provide habitat for living things, major components of the tissues in living organisms , provide a reaction medium ior chemical reactions, provide an effective transport medium, e.g. in blood and vascular tissue.
water function density
ice is less dense than liquid water because the water molecules in ice are held further apart. This is because each water molecule forms four hydrogen bonds, connecting it in a lattice shape. This means that in the colder months, ice forms an insulating later so that the water beneath doesn’t freeze, allowing aquatic organisms to survive.
water function solvent
water is a good solvent because it can form hydrogen bonds with other polar molecules or charged ionic compounds.
water function cohesion and surface tension
water molecules have a tendency to stick to other water molecules (cohesion) because the slightly positive hydrogen of one water molecule attracts the slightly negative oxygen on another water molecule
water function: High specific heat capacity
This means that water does not heat up or cool down easily, all those hydrogen bonds within water are great at absorbing energy, which means you have to add a lot of it to heat water up
water function: High latent heat of vaporisation
this means that a lot of energy is used to convert water from a liquid to a gas. This is why we feel cooler when we sweat, since the evaporation of water from our skin’s surface takes a lot of heat energy with it.
Reactant- Water is also a reactant in reactions such as photosynthesis, and in hydrolysis reactions
water function : reactant
Water is also a reactant in reactions such as photosynthesis, and in hydrolysis reactions such as digestion of starch, proteins and lipids. Its properties as a reactant do not directly draw on its polarity, but its role as a reactant is extremely important for digestion and synthesis of large biological molecules.
types of polysaccharides
animals: glycogen
plants: starch which is made up of amylopectin and amylose, cellulose
biochemical groups in carbohydrates
carbonyl groups: c=o e.g all monosaccharides
aldehyde group: h-c=o e.g glucose
keto group: c-c=o
|
c
e.g fructose
reducing sugar test
benedict’s test
method and interpretation: benedict’s test
add sample
add benedict’s solution
heat
record conclude -
brick red/ orange = positive reducing sugar
blue= negative not reducing sugar
method and interpretation: glucose test - strip test
test strip into solution
leave it - 30 second
compare the to the key
record concentration
method and interpretation: non-reducing sugar test
step 1) add solution to benedict’s and heat
step 2) add acid to hydrolyse, heat to speed hydrolysis , add alkali to neutralise
step 3) add benedict’s to it
results: h2o f- blue s- blue
glucose f- brick red s- brick red
non-reducing f- blue s- brick red
polysaccharide as good stores
long chain
insoluble
compact
branched chain
polysaccharides- long chain
a molecule of glucose can be removed when required
polysaccharides- insouble
doesn’t dissolve out of the cell/ remains in the cell
little osmotic effect, only slightly negative water potential, much less than same number of free glucose molecules
polysaccharide compact
the minimum space to store the maximum number of glucose molecules
polysaccharide branched chain
the more branches, the more chain ends. For hydrolysis enzymes to attach. Therefore quicker release of energy
test for starch method and interpretation
1) add sample
2) add I/KI iodine in potassium iodide
3) records colour
4) blue-black=positive starch present
orange = negative no starch positive
