Module 2.2 Flashcards
Biological molecules
Why can water hydrogen bond
Oxygen has more protons in its nucleus than hydrogen (more electronegative)
The shared electrons are attracted slightly towards the oxygen nucleus
The oxygen becomes delta negative
Hydrogen becomes delta positive
H bonds between hydrogen and oxygen of separate molecules
Properties of water from H bonds
High SHC
Density
High latent heat of vaporisation
Adhesion and cohesion
Solvent
Liquid
Why is high SHC good
It is difficult to heat water up
provides stable habitat
Stable temperature for enzymes
Why is high latent heat of vaporisation good
Helps with cooling from sweat/panting
Why is density good
Ice is less dense than water
Difficult for whole bodies of water to freeze (animals can live under the ice)
Ice acts as an insulating layer (stable environment underneath)
Floating ice is habitat for other animals
Why is a solvent good
Transport medium
Substances dissolved in it can react (cytoplasm)
Why is adhesion and cohesion good
In the xylem
surface tension provides habitats for insects (pond skaters)
Why is liquid good
Transport medium
dissolved substances can move around
What is a monomer
the subunit(s) used to form a polymer when more than one is joined together
What is a polymer
A molecule consisting of more than one molecule joined together
What is a condensation reaction
The joining of two molecules
Water is removed
What is a hydrolysis reaction
The breaking apart of molecules
Uses up water
Element in carbohydrates
C,H,O
Elements in proteins
C,H,O,N,S
Elements in lipids
C,H,O
Elements in nucleic acids
C,H,O,N,P
Structure of amylopectin
Formed of a-glucose monomers
Branched 1-4 and 1-6 bonds
in a spiral shape
insoluble
Amylose structure
Formed of a-glucose monomers
Not branched 1-4 bonds only
Coiled
insoluble
Glycogen structure
Formed of a-glucose monomers
Highly branched 1-4 and 1-6 bonds
Less coiled
Insoluble
Cellulose structure
Formed of b-glucose monomers
straight chains because of OH on top in b-glucose
Alternating monomer are rotated 180
Can H-bond between chains
Insoluble
Function of glycogen, amylose and amylopectin
Energy storage glycogen=animals starch (amylose and amylopectin) = plants
Insoluble as OH group on inside of coil so don’t affect the water potential of the cells
Amylopectin and glycogen are branched to provide more hydrolysis points to remove glucose from the molecule (more energy per unit time)
Glycogen in most branched as it is in animals which are more metabolically active
Compact so don’t take up space
Glucose easily snipped off
Monomers of sucrose
Fructose and glucose
Monomers of maltose
2 glucose molecules
Monomers of lactose
galactose and glucose
Triglyceride monomers
Glycerol, 3 fatty acids
Phospholipid monomers
Glycerol, phosphate, 2 fatty acids
difference between saturated and unsaturated fatty acids
Saturated have the maximum C-H bonds
Unsaturated have one or more double C bonds so have a kink
Kink means unsaturated are more liquid as tails means it is harder to compress into a liquid
Bond name between 2 or more monosaccharides
Glycosidic bond
Bond name between glycerol and fatty acids
Ester bond
Triglyceride function
Buoyancy
Protection of organs
Insulation (heat and electrical)
Energy storage (insoluble)
Energy source (can produce 2x as much energy as glucose)
Phospholipid function
Phosphate head is hydrophilic
Fatty acid tails are hydrophobic
Make up the plasma membrane (partially permeable as only small non-polar molecules can pass through tails)
Cholesterol structure
4 carbon based rings
Cholesterol function
Regulates fluidity of the plasma membrane
Makes up steroid hormones
Is hydrophobic
Bond name between amino acids
Peptide bonds
Primary protein structure
The sequence of amino acids
Peptide bonds
Secondary protein structure
Initial folding
Alpha-helix (mainly globular)
Beta-pleated sheet (Mainly fibrous)
Hydrogen bonds
Tertiary protein structure
Folding into 3D shape
Hydrophobic/philic interactions (group together, phobic go inside philic go outside of molecule)
Disulphide bridges (only between cysteine)
Ionic bonds
H bonds
Quaternary protein structure
Only in some proteins
Joining of more than one polypeptide molecules
Structure of haemoglobin
2 globin chains
2 globin chains
4 haem groups (contains Fe+ ion) (prosthetic group)
Function of haemoglobin
Haem group bonds with oxygen to transport it in the blood to respiring tissues
Structure of insulin
2 polypeptide chains
alpha chain starts with a-helix
Beta chain ends with b-pleated sheet
Insulin function
Controls blood sugar by binding to glycoprotein receptors on cells to increase their uptake of glucose from the blood
Soluble so can travel in the blood
What is a conjugated protein
Globular protein with a prosthetic group e.g. haemoglobin
Collagen properties
Mechanical strength
Collagen function
Around artery walls to prevent bursting
Tendons
Bonds
Cartilage and connective tissues
Keratin properties
Insoluble and impermeable
very strong
Keratin function
Impermeable barrier to infection
Prevents entry of water-borne pollutants
Mechanical protection
Elastin properties
Strong
Extensible
Elastin function
Stretch and recoil of skin, bladder and alveoli
Helps blood vessels stretch and recoil maintaining blood pressure
What does biuret test for
Proteins
Biuret positive result
Blue to lilac
How to carry out biuret test
Add sample to a spotting tile
Add biuret
What does benedict’s solution test for
Reducing sugars
Benedict’s positive result
Blue to green/yellow/orange/brick red depending on concentration of reducing sugar
How to carry out benedict’s test
Add sample to a test tube
Add benedict’s solution
Heat in a water bath to at least 80 degrees for 3 mins
How to test for non-reducing sugars
Do normal benedict’s test first
Add sample to test tube
Add hydrochloric acid to sample
Heat in a water bath to a boil
Neutralise with sodium hydrogen carbonate until fizzing stops
Add benedict’s solution
Heat to at least 80 degrees
What does iodine test for
Starch
Iodine positive result
Yellow to blue/black
How to carry out starch test
Add sample to spotting tile
Add iodine
What does emulsion test for
Lipids
Emulsion test positive result
White cloudy layer on top of solution
How to carry out emulsion test
Add sample to test tube
mix sample with ethanol
filter
Pour solution into water
leave to settle
How to determine concentration of substance - colorimetry
serial dilution of known concentration
Set colorimeter to red
Calibrate with distilled water
Test absorption for known concentrations
Plot calibration curve
Test absorption for unknown
Find absorption for unknown on calibration curve then down to concentration
R value calculation
Distance moved by the solute / distance moved by the solvent
Cellulose cell wall function
Plant cell walls
High tensile strength prevents cells from bursting when turgid
Criss cross wall for extra strength
Space between microfibrils making it fully permeable for water and mineral ions to pass through
Cellulose embedded in pectin
Can be reinforced with waxes (suberin, cutin) for waterproofing
Pepsin structure
Single polypeptide chain
Has very few basic R-groups
Mainly acidic R-groups so is stable in the stomach as acidic R-groups cannot accept H+ ions
Pepsin function
Digests protein
In the stomach
