Biological molecules

• what is the theory of evolution

  the theory that all organisms on earth are descended from one or a few common ancestors and they have changed and diversified over time .
• examples of polymers

  carbohydrates , protiens and nucleic acids
• what are polymers

  large complex molecules composed of long chains of monomers joined together
• what are monomers

  small basic molecular units that can form a polymer
• examples of monomers

  monosaccaharides amino acids and nucleotides
• what is condensation reaction


  it forms a chemical bond between monomers releasing a molecule of water
• what is hydrolysis reaction

  it breaks the chemical bond between monomers using a water molecule
• what is the theory of evolutio


  The theory that all organisms on Earth are descended from one or a few common ancestors and that they have changed and diversified over time.
• examples of polymers

  carbohydrates, proteins, and nucleic acids
• what are polymers

  long complex molecules composed of long chains of monomers joined together
• what are monomers


  small basic molecular units that form a polymer
• examples of monomers

  Monosaccharides, amino acids and nucleotides
• what is condensation reaction


  Forms a chemical bond between monomers, releasing a molecule of water
• what is hydrolysis

  breaks the chemical bond between monomers using a water molecule
• cytochrome c is a protien used in the reaction of respiration and is found across species of animals plants and unicellular organism . suggest why this is evidence for evolution

  it is present in cells of a wide variety of organisms suggesting that they could all have descended from a common ancestor
• what are monosaccharides

  simplest sugar and building block of carbohydrates
• the carbohydrates contain

  C, H, O
• what type of sugar is glucose


  hexose
• two types of glucosse

  alpha and beta
• what are isomers


  compounds with the same molecular formula but different structures and properties
• structure of alpha glucose

  alpha - OH down

  
• structure of beta glucose

  OH up

  
• what is a disaccharide

  two monosaccharides joined together
• how are monosacharides formed

  joined together by condensation reaction - a glycosidic bond forms between the two monosaccharides as a molecule of water is released
• two alpha glucose together

  maltose
• sucrose

  condensation by glucose + fructose
• lactose


  glucose + galactose
• what are reducing sugars and example

  All monosaccharides and some disaccharides

  eg - maltose and lactose
• how to test for reducing

  add benedict reagent which is blue to a sample and heat it in a water bath thats brought to boil .

  positive - green / yellow / orange / brick red precipitate
• more accurate way of doing the reducing sugar test

  filter the solution and weigh the precipitate

  or

  remove the precipitate and use a colorimeter to measure the absorbance of the remaining benedict reagent
• test for non reducing sugar

  - heat with benedicts - no change

  - therefore, add dilute hydrochloric acid (hydrolyses glycosidic bond)

  - then add sodium hydrogencarbonate (neutralises solution)

  - heat with benedict - turns brick red

  
• what are polysaccha

  when more than two monosaccharides are joined together by condensation reactions
• lots of alpha glucose

  amylose
• when asking to draw a polysacharide or monosacharide of a molecule

  remove or add H
• starch is a mixture of two polysaccharides of alpha glucose

  amylose and amylopectin
• describe amylose

  A long unbranched chain of alpha glucose

  Coiled structure

  Compact - good for storage

  Joined by 1-4 glycosidic bonds

  
• describe amylopectin

  Made by 1-4 glycosidic bonds

  Some 1-6 glycosidic bonds

  Branched structure

  Very compact

  Free ends where glucose can be added or removed

  Insoluble

  
• uses of starch

  it is insoluble in water so does not affect water potential

  so it doesnt cause water to enter cells by osmosis which makes them swell

  this makes it good for storage
• describe glycogen

  •Storage of carbohydrates in animals found in liver

  •Alpha-1,6-glucose and alpha-1,4-glucose links

  •Similar to amylopectin (starch) due to branched structure very compact so more storage

  
• describe cellulose


  Alternate B-glucose molecules upside-down. Unable to coil or form branches. 1,4 bonds. Cellulose molecules joined by H-bonds to form microfibrils, then macrofibrils, then fibres.

  strong fibrils mean cellulose provides structural support for cells