Biological molecules

• What is a monomer?


  A small unit from which larger molecules
• What is an isomer?

  Two molecularly identical substances with different arrangements
• What is a polymer?

  A molecule made from a large number of monomers bonded together
• Examples of monomers


  Glycogen, cellulose, starch - monosaccharides

  Proteins - amino acids

  DNA and RNA- nucleotides
• What is a condensation reaction?

  -Two monomers

  -Bonded together

  -Removal of a water molecule
• What is a hydrolysis reaction?

  -Bond broken

  -Between two monomers

  -Addition of a water molecule
• What is a monosaccharide?

  The monomers of carbohydrates
• Examples of monosaccharides


  Glucose, galactose, fructose
• What is the bond formed by a condensation reaction and how is it represented?

  A glycosidic bond (O)
• What is a disaccharide?

  Two monosaccharides joined together by a condensation reaction
• examples of disaccharides


  Lactose - Glucose and galactose

  Sucrose - Glucose and fructose

  Maltose - Glucose and glucose
• Structure of alpha glucose

  
• Structure of beta glucose

  
• What is a polysaccharide?

  A chain of monosaccharides joined together
• Examples of polysaccharides


  Glycogen, starch and cellulose
• Starch structure and function

  Made of amylose and amylopectin - both made of alpha glucose units

  Amylose - Long coiled chains

  Amylopectin - Short branched chains

  
  

  Used as a storage molecule - does not impact osmosis
• Glycogen structure and function

  Formed by alpha glucose units

  Lots of short branches so bonds can be easily hydrolysed to access energy quickly - does not affect osmosis
• Cellulose structure and function

  Formed from beta glucose units

  Connected by hydrogen bonds to form fibrils

  Structural molecule found in cell walls as they can withstand high osmotic pressure
• What is the difference between alpha and beta glucose bonding?

  Beta glucose flips 180 degrees to make a chain
• What is the test for reducing sugars?

  Add Benedict's solution to the sample and heat in a water bath

  If the test is positive, solution changes from blue to brick red
• What is the test for non-reducing sugar?

  Add hydrochloric acid and boil

  Neutralise using sodium hydrogencarbonate and carry out Benedict's test

  Solution will turn orange or brick red
• What chemical is used to test for starch? Test results

  Iodine, turns black in presence of starch
• Chemical test for proteins


  Biuret solution turns purple
• Chemical test for lipids

  Add ethanol and shake, add distilled water, emulsion forms
• What is a triglyceride?

  A type of lipid made of glycerol and 3 fatty acids
• What is a phospholipid?

  A glycerol with 2 fatty acids and a phosphate
• What is the bond that forms between the fatty acid and glycerol?

  An ester bond
• What is the difference between monounsaturated and polyunsaturated?

  Monounsaturated = One double bond

  Polyunsaturated = Many double bonds
• Properties and uses of lipids?

  Fatty acid tails are hydrocarbons - energy storage

  Fatty acid tails are hydrophobic - water proofing

  Lipids are non-polar molecule - insoluble in water
• Structure of an amino acid?

  A carbon atom, with an amine group, carboxyl group, hydrogen and an R group

  
• What bonds form between amino acids?

  Peptide bonds
• What is the name of two amino acids and a chain or a chain of amino acids bonded together?

  Dipeptide/ polypeptide
• Name and describe the four protein structures

  Primary - A chain of amino acids

  Secondary - A folded chain of amino acids

  Tertiary - A complex 3D protein - folded secondary

  Quaternary - Multiple tertiary structures
• What bonds hold proteins together?

  Hydrogen, ionic and disulphide bridges
• What is the function of an enzyme?

  Biological catalyst that reduces the activation energy for the reaction to take place whilst remaining unchanged
• What is the induced fit theory?

  Enzyme has similar shape to specific substrate, they mould to fit the substrate to form an enzyme-substrate complex

  Puts strain on bonds, lowering activation energy

  When reaction finishes, enzyme returns to original shape
• How do temperatures and pH affect enzymes?

  Interfere with bonds that hold the complex 3D structure together

  -affects the shape of the active site

  -causes enzyme to denature

  -Enzyme-substrate complex cannot form
• How do non-competitive inhibitors affect enzymes?

  They bind to the allosteric region, changing its 3D shape - active site no longer complementary
• How do competitive inhibitors affect enzymes?

  Binds directly to the active site - blocks substrate from forming an enzyme-substrate enzyme - substrate can kick out at high concentrations
• What is the structure of a nucleotide?

  A phosphate group, a pentose sugar, a nitrogenous base