Topic 1 - A: Biological molecules Flashcards
Difference between monomers and polymers
Polymers are large, complex molecules composed of long chains of monomers joined together
Monomers are small basic molecules that can form a polymer
What is a condesation reaction
Forms a chemical bond between monomers and releases water
What is a hydrolisis reaction
Breaks chemical bonds between monomers using a water molecule
What is a monosaccharide
Contains elements H, C and O. Monosaccharides make up carbohydrates
Draw the two types of glucose
Alpha - OH is on bottom
Beta - OH is on top
What is a dissacharide
Formed when two monosaccharides join together via a condensation reaction - a glycosidic bond forms between two monosaccharides as a molecule of water is released
Describe benedicts test for reducing sugars.
Add benedicts reagent (blue) to your sample and heat in a water bath thats been brought to boil. If the test is posotive it will turn brick red, if negative it will stay blue
How to test for non reducing sugar
After having tested for a reducing sugar the solution may have stayed blue, this means there could still be a non reducing sugar still present. Heat a new sample with dilute hydrochoric acid then neutralise with alkaline. Then you must heat with Benedicts reagent, if the sample turns brick red, then there is a non-reducing sugar present, if it stays blue, there is neither a non-reducing sugar or a reducing sugar
How is Sucrose formed
Glucose + Fructose
How is Lactose formed
Glucose + Galactose
Function of starch
Plants store excess glucose as starch
Starch is a mixture of to polysaccharides :
Amylose: long unbranched chain of a-glucose
coiled structure make it compact so its good for storage
Amylopectin: long branched chain of a-glucose
as it has more side branches , enzymes can break it down more efficiently
therefore it is good for rapid energy
release.
Function of glycogen
Animal cells store excess glucose as glycogen.
It has a very similar structure as amylopectin, except it has loads more side branches, this means the glucose can be released at a very high rate
Its also very compact meaning it is good for storage
Function of cellulose
Cellulose is a long unbranched chain of beta glucose unlike Starch and Glycogen
When the b-glucose molecules bond they are linked together by weak hydrogen bonds to create strong fibres called microfbrils. These strong fibres mean cellulose provides structural support for cell walls in plants.
How to test for presence of starch
Add iodine dissolved in pottasium iodide solution to the test sample. If starch is present, the colour will change from orange/yellow to blue
What are tryglicerydes
One molecule of glycerol with three fatty acids attached to it.
Fatty acids have long tails made of hydrocarbons
These tails are hyrophobic
What is the difference between saturated and un-saturated fatty acids
Saturated-no double bond
Unsaturated-double bond present between carbon atoms
How are triglycerides formed
formed by condensation reaction
As the fatty acid and glycerol join a watere molecule is released.
What are phospholipids
one of the fatty acids is replaced by a phosphate group. The phosphate group is hydrophilic and the fatty acid is still hydrophobic like regular.
These are stored in the cell membrane
Properties of triglycerides and phospolipids
Triglyceride: Long hydrocarbon tails of fatty acids contain alot of energy
Insoluble so they dont affect water potential meaning the cell will swell
Phospholipid: Make up the bilayer of the cell membrane and control what enters and leaves a cell
The heads are hydrophillic and their tales are hydrophobic so they form a double layer with their heads facing outwards towards the water and their tales on the inside which are hydrophobic meaning water-soluble substances cant pass through easily
Describe the emulsion test
Shake the test substance with ethanol for about a minute then pour solution into water
Any lipid will show as milky emulsion
What reaction links amino acids together and what bond forms between them
Condensation reaction
Peptide reaction
What reaction breaks down dipeptides and polypeptides
hydrolisis
What is the primary structure
The sequence of amino acids in the polypeptide chain
What is the secondary structure
The polypeptide chain doesn’t remain flat
i.e. Hydrogen bonds form between the amino acids in the chain making it automatically coil
What is the tertiary structure
The coiled or folded chain of amino acids is folded or coiled even further
Further bonds created (hydrogen and ionic)
Disulfide bridges also form
What is the quaternary structure
Some proteins are made from several seperate polypeptide chains held together by bonds
The quaternary structure is the way these polypeptide chains are assembled together.
How to test for proteins
BUIRET TEST
The test solution must be alkaline-to do this add a few drops of sodium hydroxide solution
Then add copper sulfate solution
If there is a protein present the solution will turn purple, if there’s no protein it will stay blue
What is the induced fit model
Substrate binds into active site, but the active site changes slightly to fit substrate. The products are then produced like normally
What factors affect enzyme activity
Temperature -higher temperature, higher rate of reaction until a certain temperature where the enzyme will denature
pH - Generally optimum pH is 7
Substrate concentration - The higher the substrate concentration the higher the rate of reaction, this is true until you reach the point of saturation where all the active sites are filled and it will not make a difference if there are more substrates
Enzyme concentration works the same as the above
Competitive inhibitors
molecules that have a similar shape to that of the substrate molecules. They compete with the substrate to block the active site from the substrate. no reaction takes place with them, they purely block the active site from reacting
In the long run it will reach the same rate of reaction it will just take longer to reach this point
Non competitive inhibitor
Bind to the enzyme away from the active site changing the shape of the active site meaning substrate molecules can no longer fit to the active site.
This means rate of reaction will never be reached as the shapes are being changed forever.
