2.2 biological molecules

• monomer

  a single molecule that may combine with other monomers to build up larger molecules called polymers
• polymer

  a large molecule built up from many similar monomers joined together by covalent bonds to form a chain or branched chain
• monomers and polymers of carbohydrates

  monosaccharides -> glucose, fructose, galactose, ribose, deoxyribose

  
  

  polysaccharides -> starch (amylose, amylopectin), cellulose, glycogen
• monomers and polymers of proteins

  Monomers -> amino acids (glycine, valine, alanine)

  Polymers -> polypeptides (amylase, lysosome)
• monomers and polymers of lipids

  Monomers -> glycerol and 1-3 fatty acids

  Polymers -> mono, di, triglycerides
• monomers and polymers of nucleic acids

  monomers -> nucleotides

  polymers -> DNA, RNA
• elements in carbohydrates

  carbon, hydrogen, oxygen
• elements in lipids

  carbon, hydrogen, oxygen
• elements in proteins

  carbon, hydrogen, oxygen, nitrogen, sometimes sulfur
• elements in nucleic acids

  carbon, hydrogen, oxygen, nitrogen, phosphorus
• catabolic reactions

  reactions of metabolism that BREAKDOWN molecules into smaller units to release energy(e.g. respiration, digestion)

  
• anabolic reactions

  reactions of metabolism that CONSTRUCTS/BUILD UP molecules from smaller units. These reactions require energy from the hydrolysis of ATP.(e.g. protein synthesis)

  
• condensation reaction

  A chemical reaction where 2 molecules JOIN TOGETHER with a covalent bond, forming larger molecules and releasing 1 molecule of water.

  -> joining 2 molecules together by removing water

  
• hydrolysis reaction

  A chemical reaction where the covalent bond between 2 molecules is BROKEN with the addition of a water molecule, separating the 2 molecules.

  -> splitting apart molecules through the addition of water

  
• the 3 types of saccharides

  monosaccharides: glucose, fructose, galactose, ribose

  disaccharides: sucrose, maltose, lactose

  polysaccharides: starch (amylose, amylopectin), cellulose, glycogen
• how monosaccharides combine to make the disaccharides and polysaccharides

  monosaccharides can join together to form disaccharides and polysaccharides by glycosidic bonds which are formed in condensation reactions

  
• Monosaccharides

  a simple sugar with general formula Cx(H2O)y

  is C=3, trios (glyceraldehyde)

  if C=5, pentose (ribose, deoxyribose)

  if C=6, hexose (glucose, galactose)

  
• glucose

  a monosaccharide containing 6 carbon atoms, so a hexose monosaccharide. it is the main substrate for respiration so it is of great importance C6H12O6
• the isomers of glucose and draw them

  alpha glucose and beta glucose

  
• alpha glucose

  glucose where on C1:

  - H on top

  - OH on bottom

  
• beta glucose

  glucose where on C1:

  - OH on top

  - H on bottom

  
• draw ribose and deoxyribose (as a pentose monosaccharide)

  
• disaccharide

  A double sugar molecule made of two monosaccharides bonded together through a condensation reaction and have been joined together by a glycosidic bond.

  
• formation of maltose

  alpha glucose + alpha glucose -> maltose + water

  
  

  - maltose found in germinating seeds

  
• formation of lactose

  alpha glucose + beta galactose -> lactose + water

  
  

  - lactose found in milk

  
• formation of sucrose

  alpha glucose + fructose -> sucrose + water

  
  

  - sucrose found in sugar cane

  
• glycosidic bond


  a covalent bond formed when 2 carbohydrate molecules are joined together by a condensation reaction
• polysaccharides

  polysaccharides are large insoluble molecules consisting of many monosaccharides joined together via condensation reactions (starch, cellulose, glycogen)

  
• Amylose, structure and function

  - amylose is an unbranched chain of glucose molecules joined by 1-4 glycosidic bonds.- as a result of that amylose is coiled and thus it is a very compact molecule meaning it can store a lot of energy (store a lot of glucose)- it is insoluble and won't affect water potential- source from plant and subunit is alpha glucose

  
• Amylopectin, structure and function

  - Amylopectin is branched and is made up of glucose molecules joined by 1-4 and 1-6 glycosidic bonds.- due to the presence of many side branches the surface area increases for rapid hydrolysis back to glucose as it is rapidly digested by enzymes. therefore, energy is released quickly.- it is insoluble and won't affect water potential- source from plant and subunit is alpha glucose

  
• cellulose, structure and function

  - component of cells walls in plants- composed of long, unbranched chains ofbeta glucosewhich are joined by 1-4 glycosidic bonds.- chains are held in parallel by many hydrogen bonds to form fibrils.-Microfibrilsare strong threads which are made of long cellulose chains joined together byhydrogen bondsand they providestructural supportin plants cells- it is insoluble and won't affect water potential

  
• Glycogen structure and function


  - Glycogenis the main energy storage molecule inanimals- formed from many molecules ofalpha glucosejoined together by1-4 and 1-6 glycosidic bonds.- It has alarge number of side branchesmeaning that glucose & therefore energy, can be released quickly.- it is a relativelylarge but compactmolecule thus maximising the amount of energy it can store.- it is insoluble and won't affect water potential

  
• starch (amylose and amylopectin), cellulose and glycogen

  table of source, monomer, types of glycosidic bond, branches, function, structure and how the structure leads to the function

  
• lipids

  non polar molecules (that include fats, oils, and cholesterol)

  - this means that there are no positive or negative areas within the molecules and for this reason, lipids are not soluble in water

  -> do not affect cell water potential

  
  

  - they are large complex molecules known as macromolecules, which are built from its repeating units (monomers) - triglycerides, phospholipids and sterols
• saturated lipids (+ structure)

  - all single bonds

  - solid at room temp (higher melting point)

  .,ex: butter, wax,blubber (animal fats)

  
• unsaturated fats (+ structure)

  - contain carbon=carbon double bonds

  - liquid at room temperature

  ex. oils (from plants)

  
• the greater the number of unsaturated bonds...

  the wear the intermolecular bonds resulting in lower melting point, and as a result, saturated fats which don't contain any double bonds are solid at room temperature and unsaturated lipids are liquid at room temperature

  
• draw a triglyceride

  
• triglycerides

  - triglycerides are lipids (macromolecules) made of one molecule glycerol and 3 fatty acids, joined together by ester bonds formed in condensation reactions

  
  

  - some triglycerides contain a mix of different fatty acids

  - triglycerides are used as energy reserves in plants and animals

  -> the ester bonds can be broken by hydrolysis

  
• phospholipids

  - a lipid consisting of a glycerol bound to two fatty acids and a phosphate group.

  (one of the fatty acids of a triglyceride is substituted by a phosphate containing group)

  
  

  - phosphate heads are hydrophilic and the tails are hydrophobic

  - as a result, phospholipids form a lipid bilayer when they are in contact with water as heads are on the outside as they are attracted to water and tails are on the inside as they move away from water