2.2 Biological molecules Flashcards
Why is water polar?
Oxygen has more (+ve) protons in nucleus than H
Exerts stronger force for shared electrons making it slightly negative, and hydrogen slightly positive
Why is it important that water is a liquid? (4)
habitats for living things
major component of tissues in living organisms
reaction medium for chemical reactions
transport medium e.g. blood
Ice only gets denser as it gets colder up until 4 degrees. After that, it gets less dense because its polar.
Why is this important?
stable environment for aquatic organisms
insulation in the cold
Because water is polar, the positive and negative parts of the water are attracted to the negative and positive parts of the solute.
Why is it important that water is a good solvent?
molecules can transport whilst dissolved in it.
How does water have cohesion and surface tension?
water molecules at surface are all hydrogen bonded to mols beneath so surface of water contracts giving it an ability to resist force applied to it
What is specific heat capacity?
the amount of heat energy required to heat one kg of water by 1 degree
Why is it good that water has a high specific heat capacity? (2)
stable temp / stable environment for aquatic organisms
stable temp for enzyme controlled reactions in living things
Formula for alpha and beta glucose?
C6 H12 O6
What is the difference between alpha and beta glucose?
the right h and oh on the beta is the other way around
what does a glucose and a glucose make?
maltose
what does alpha glucose and fructose make?
sucrose
what does beta galactose and alpha glucose make?
lactose
what does beta glucose and beta glucose make?
cellobiose
What two polysaccharides is starch comprised of?
amylose and amylopectin
Which out of glycogen, amylose, and amylopectin are branched?
glycogen and amylopectin (1,6 glycosidic bonds)
Why is it good that glycogen are compact in dense granules, and branched? (2)
dont occupy a lot of space
easily snipped off when required for respiration
chains of b glucose joined by condensation reaction are straight because every other glucose molecule is rotated by x degrees
180
Difference between triglyceride and phospholipid structure?
triclyceride= glycerol+ 3 fatty acid chains phospholipid= glycerol+2 fatty acids + phosphate group
What are proteins? (1)
A large polymer of amino acids
What is primary structure?
Primary= order/sequence of amino acids
What is the amine group of an amino acid comprised of?
N H H
What is the carboyxl group of an amino acid comprised of
C=O
-OH
Name 3 fibrous proteins
Collagen
Keratin
Elastin
Name 3 globular proteins
Haemoglobin
Insulin
Pepson
How do you test for starch/
Iodine solution on white spotting tile
Blue-black colour indicates starch is present
How do you test for reducing sugars?
Add benedicts solution then heat in water bath 80oC for 3 minutes
orange red precipitate indicates reducing sugar is present
How do you test for non-reducing sugars?
Hydrolyse the bond to free up the reducing groups by boiling with hydrochloric acid
neutralise with sodium hydrogencarbonate
test for reducing sugar as normal
How do you test for lipids?
add ethanol
add water
cloudy white emulsion indicates presence of lipids
How do you test for proteins?
biuret test
lilac colour indicates protein
How is glucose structurally different from fructose?
Fructose has a five membered ring and glucose has a six membered ring
State 4 differences between haemoglobin and collagen. (5)
Collagen= triple helix. Haemoglobin=2 helix 2 pleated sheets
C= fibrous H=globular
C=1 type of polypeptide chain H=2 types alpha H betaPS
C=only made of polypeptide chains H= has prosthetic haem group
C=function is fibrous connective tissue H=function transport oxygen
Give 2 reasons why water is a good transport medium
Polar- good solvent, can dissolve glucose
Hydrogen bonds allow water to flow as a body
Liquid at room temperature
Describe the nature of disulphide bonds (4)
Joins 2 sulphur atoms
covalent bond
Between R groups
Strong
What is secondary structure?
Secondary= the way it folds or coils- alpha helix or beta pleated sheet
What is tertiary structure?
Tertiary= interaction between r groups when those coils and pleats themselves fold
What is quarternary structure?
Quarternary=more than one polypeptide chain
State and explaiun 2 ways glucose is suited to its funcction in living organisms.
soluable so easily trasported
small so diffuse across cell membranes
easily broken down/hydrolysed for ATP
Why do mammals use glycogen as an energy store? (4)
1 insoluble , so has no effect on ,
water potential / Ψ (of cell)
2 metabolically inactive
3 compact / lots can be stored in a small space
4 able to store , large amounts / lots , of energy
5 (highly branched so) has lots of ends for ,
adding / removing , glucose (when needed)
or
can be broken down , fast / quickly / rapidly ,
to release glucose
What 3 things is ATP made of?
adenine
ribose
phosphate
