Biological molecules Flashcards
Functions of carbohydrates
Energy source Structural components Storage compounds Transport Cell recognition Metabolites
Test for carbs - reducing sugar
1cm3 Benedictus solution with 2cm3 of carb solution
Water bath 5mins 60C
Brick red +
To
Blue -
Test for non reducing sugars
Carry out Benedictus test If negative 1cm3 of dilute HCl Water bath 5mins Neutralise 1cm3 NaOH retest with Benedicts
Test for carbs (i)
3 drops of iodine In 2cm3 of carb solution
Make sure solution is cold
Blue black +
Brown -
2 types of glucose and the difference
Alpha - H
OH
Beta - OH
H
Sucrose
Lactose
Made from?
Glucose and fructose
Glucose and galactose
Polysaccharides
Long chain of monosaccharides bonded together by glycosidic bonds via condensation reactions
Large stable and insoluble
Most common polysaccharides
Glycogen
Starch
Cellulose
Main storage polysaccharides in plants
Amylose
Helix
Forms starch w/ 1-4 glycosidic bonds
Compact and long term
Amylopectin
Branched so quicker to hydrolyse to glucose
1-4 and 1-6 glycosidic binds to for starch
2 types of glucose as polysaccharides are
Glycogen -a
Branched, compact, insoluble,
Cellulose - ß every other glucose molecule flipped so atoms line up to form H2O
Branched, meshed layered network, permeable and strong
Triglycerides are lipids made from
1 glycerol and 3 fatty acids ( 14-22 C atoms)
Fats have single bonds
Oils have1 or more double bonds
Phospholipids made up of
1 glycerol
1 phosphate group makes it polar hydrophilic PO4-3
2 fatty acids hydrophobic
Phospholipids form
Bilayers in membranes
Droplets called micelles ( in water )
Bilayer droplet called a liposome
Test for lipids
2cm3 of sample and 5cm3 of ethanol
Shake
Add 5cm3 of water and shake
If a lipid is present it will dissolve and form a cloud white emulsion
Proteins
Made of amino acids (20 different types)
NH3,CHR,COOH
R group is what makes the amino acids different
Primary protein
Secondary protein
Tertiary protein
Quaternary protein
- Order of amino acids
- a helix ( coil to form filaments) or ß pleated sheet ( run in same or opposite direction)
- a and ß (secondary) bonded together by hydrogen bonds, ionic bonds and disulphide bridges ( covalent bonds between sulphur) poly peptide chain
- 2 or more polypeptide chains linked together either
Globular - tightly folded into a spherical like shape
Fibrous - cross linked and intervals to form fibres and sheets
Test for proteins
Sample of solution and an equal amount of NaOH
Few drops of copper(ii) sulfate
Purple +
Blue -
Enzymes
Globular Proteins that change the rate of reaction by dec the activation energy
Metabolic rate
The rate of catabolic and anabolic reactions that can be sped up by enzymes
Factors that may effect rate of reaction
Enzyme conc - as conc inc rate inc until substrate is limiting and ot no longer inc
Substrate conc -as conc inc rate inc until enzymes is limiting and rate does nit inc
Temp - not enough energy, optimum ( varies ), enzyme denatures
pH - as you move away from optimum ( varies) enzyme denatures however can return to normal when optimum is met
Why pH effects the rate of reaction w/ enzymes
- Change in pH alters con of H+ or OH- ions
- This change will disrupt the H bonds holding together 2nd and 3rd protein structure and the Ionic bonds in the 3rd
- causes the 3D structure to change therefore active site changes
- prevents formation of substrate-enzyme complex as enzyme is denatures
Mechanism for enzyme action
Induced fit hypothesis
Enzyme active site changes shape slightly to fit the substrate which puts strain on the substrate molecule
Strain distorts and particular bond and therefore lowers the activation energy
Induced fit is better than lock and key because…
Shows how other molecules can effect enzyme activity
Shows how enzymes lower activation energy
Enzyme inhibition - competitive inhibitor
Competes with the substrate fir position on active site
Of the amount of inhibitor is fixed the % of inhibition can be dec by inc the substrate conc
