fuck biological molecukes Flashcards
What does Benedict’s test for?
Reducing sugars
Outlines the steps in benedicts test [3]
- Add equal vol of reagent to the sample to be test
- heat the mixture in a water bath at 100C for 5 mins
- results - colour change from blue to (green, yellow, orange, brick red)
Outline the steps for benedicts test for non reducing sugars [3]
- Hydrolyse non reducing sugars by adding equal volume of HCl
- heat in boiling water bath for 5 mins
- neutralise mixture with hydrogen carbonate solution
How can the Benedict’s test be made more quantitive? [2]
- Measure time till first colour change is produced
- create standard solutions of known concentrations and compare colour change to estimate concs
Outline Biuret test for proteins [2]
- add drops of the solution to sample and swirl
- Pos = purple, Neg, stays blue
Define monomer
A single subunit that is used to build larger polymers
Define polymer [2]
- Large molecule made of repeating subunits (monomers)
- joined by condensation
Define Macromolecule
A large biological molecule
Define monosaccharide
A single unit of carbohydrate
Define Disaccharide [2]
- 2 units of carbohydrate joined by condensation
- held by glycosidic bond
Define polysaccharide [3]
- a polymer with monomers of monosaccharides
- joined together by condensation
- held by glycosidic bonds
Describe structure of glucose [3]
- Hexagon shape
- 4 alternating OH and H bonds outside
- one CH2OH and one O
What is the difference between A and B glucose?
OH group for alpha is on the bottom while beta is on the top
What happens in condensation reactions - with reference to glycosidic bonds & the type of bond [4]
- A chemical bond forms between two molecules
- a molecule of water is produced
- H is removed from one molecule and OH from another
- When this happens between carbs, it’s called a glycosidic bond
What is meant by reducing and non reducing sugars? [3]
Reducing - able to reduce other sugars to form di or poly saccarides.
due to free free groups which can be condensed. All monosaccharides are reducing sugars
Non reducing - don’t have condensable free group to reduce
Three examples of reducing sugars
Glucose
Fructose
Maltose
Example of a non reducing sugar
Sucrose
State how sucrose is formed via the formation of a glycosidic bond [3]
Alpha glucose and fructose form sucrose
via the omission of h2o (condensation reaction)
forming a glycosidic bond between them
How are glycosidic bonds broken? What is this known as? [2]
Water used to break the bonds.
Known as hydrolysis
Describe the structure of Amylose [3]
1,4 glycosidic bonds
unbranched
helical
Describe the structure of amylopectin [2]
1,4 and 1,6 glycosidic bonds
branched
How do the structures of both Amylose and Amylopectin relate to their function? [2]
Large - no diffusion out of cells
Insoluble - No osmotic effect on cells
How does the structure of Amylose relate to its function? [2]
Amylose has 1,4 glycosidic bonds and is unbranched and helical. These properties make it compact and allow it to store a lot of alpha glucose
What do Amylose and amylopectin do
Act as a storage polymer of alpha glucose in plants
How does the structure of amylopectin relate to it’s function? [2]
It has 1,4 and 1,6 bonds, this means it has many branches, which means it has many terminal ends from rapud hydrolysis into glucose
Describe the structure of glycogen [4]
- 1,4 and 1,6 glycosidic bonds
- branched = many terminal ends for hydrolysis
- insoluble
- compact
Describe the function of glycogen
Main storage polymer of alpha glucose in animal cells
Describe the structure of cellulose [4]
- 1,4 glycosidic bonds
- straight chain, unbranched molecule
- alternate glucose molecules are rotated 180*
- H bond crosslinks between parallel strands form microfibrils (good strength)
Describe the function of cellulose
Polymer of beta glucose, gives rigidity to plant cell walls and prevents bursting under turgor pressure.
What’s the difference between saturated and unsaturated fats? [2]
- Saturated fats have no C=C bonds and are solid at room temp
- Unsaturated fats have one or more c=c bonds and are liquid at room temp due to weak intermolecular forces
Describe the structure of a triglyceride, with reference to how it is formed [2]
One molecule of glycerol forms ester bonds with three fatty acids,
these can be saturated or unsaturated - via condensation reactions
Relate the structure of triglycerides to their functions [5]
- High energy to mass ratio - energy storage
- insoluble hydrocarbon chain - no effect on water potential of cells (waterproofing)
- slow conductor of heat - thermal insulation
- less dense than water - buoyancy of aquatic animals
- protects organs - resistant to large amounts of force
Describe the structure of phospholipids [4]
- Polar
- Glycerol backbone attached to
- 2 hydrophobic fatty acid tails and
- 1 hydrophilic phosphate head
Describe the function of phospholipids [2]
- Forms phospholipid bilayer in water
- the hydrophobic tails allow for control of movement of water soluble molecules in and out of cells
Describe the common structure of an amino acid [4]
- Amide group
- variable side chain
- carboxyl group
- h atom
How are peptide bonds formed? [3]
- The OH is lost from the carboxyl group
- and a H from the Amide group
- forming a peptide bond
Describe a name the process by which peptide bonds are broken [3]
- H2O is split into h+oh
- OH returns to the carboxyl group, and H returns to amide group
- hydrolysis reaction
What is the primary structure of a protein? [2]
A sequence of amino acids in a polypeptide
held by peptide bonds
What is secondary structure? [4]
The regular folding of a polypeptide
into alpha helices
and beta pleated sheets
held by hydrogen bonds
What is tertiary structure? [4]
The further coiling of a protein into its functional 3D shape
Held by hydrogen, ionic and disulphide bonds
and hydrophobic interactions
What is quaternary structure? [3]
The folding of 2 or more polypeptides into a 3D shape
which may include prosthetic groups
held by hydrogen, ionic, disulphide bonds and hydrophobic interactions
Describe the structure of haemoglobin [5]
- Globular structure
- 2 alpha chains and 2 beta chains, 4 prosthetic haem groups
- water soluble (dissolve in plasma)
- Fe2+ haem group forms coordinate bond with O2
- tertiary strcuture changes so its easier for O2 molecules to bind
State the difference between blobular and fubrous proteins [2]
- Globular proteins are soluble and involved in physiological processes
- Fibrous proteins are insoluble and have a structural role
State the features of a globular protein with reference to haemoglobin [4]
- Spherical and compact
- hydrophilic R groups face outwards and hydrophobic R groupd face inwards
- Involved in promarily in physiological roles
- compact nature means haemoglobin can transport more oxygen per unit of blood
Describe the structure of collagen [4]
- Fibrous protein
- made of 3 polypeptide chains coiled to form a triple helix
- every third amino acid is glycine
- collagen molecules lie paralell to form collagen strands, held by staggered cobalent bonds cross bridges between lysine residues
How does hydrogen bonding occur in water?
The S+ hydrogen on one water molecule is attarcted to the lone pair of the S- oxygen on another water molecule.
What are the properties of water due to hydrogen bonding? [6]
- High surface tension
- Acts as a solvent for water soluble molecules
- high specific heat capacity
- high latent heat of vaporisation
- high boiling point than expected
- ice less dense than liquid water
