biology

• Starch is a biological molecule that is made from many molecules of glucose joined together in a chain. Plants make glucose during photosynthesis and then the molecules of glucose are joined together to produce starch.
• molecules in living organisms fall into 3 categories; carbohydrates, proteins, and lipids. all contain carbon and are known as organic material
• carbohydrates - sugars (monosaccharides) or polysaccharides
• carbohydrate- carbon, oxygen, and hydrogen
• protein - carbon, oxygen, hydrogen, nitrogen
• lipid - carbon, oxygen, and hydrogen
• protein - amnio acids
• lipd - glycerol, fatty acid
• monosaccharide is a simple one unit sugar, such as glucose or fructose
• disaccharides consists of two monosaccharides bonded together
• if we have a longer chain of monosaccharides bonded together, then this is now called polysaccharise. examples would include starch and gltcogen
• proteins are an essential molecule for life. they contain carbon, oxygen, hydrogen and nitrogen as their key elements. proteins similar to that of carbohydrates are large molecules and are made up of smaller subunits called amnio acids
• lipids contain carbo, oxygen, and hydrogen. this is another large molecule made up from smaller molecules. lipids are fats or oils. fats if solid at room temperature and oil if liquid at room temperature. lipids are often comprised of 2 smaller units called glycerol and fatty acids
• Carbohydrates


  Contain the elements carbon, hydrogen and oxygen
• Monosaccharide


  A simple sugar e.g. glucose (C6H12O6) or fructose
• Glucose molecules


  • Contain lots of energy which can be released in respiration by breaking the bonds between the carbon atoms
• Fats

  • Most fats (lipids) in the body are made up of triglycerides
  • Their basic unit is one glycerol molecule chemically bonded to three fatty acid chains
  • The fatty acids vary in size and structure
  • Lipids are divided into fats (solids at room temperature) and oils (liquids at room temperature)
• Disaccharide


  Made when two monosaccharides join together
• Disaccharides


  • Maltose (formed from two glucose molecules)
  • Sucrose (formed from one glucose and one fructose molecule)
• Polysaccharide


  Formed when lots of monosaccharides join together
• Polysaccharides


  • Starch
  • Glycogen
  • Cellulose (all formed when lots of glucose molecules join together)
• Polysaccharides


  • Insoluble and therefore useful as storage molecules
• Proteins

  • Proteins are formed from long chains of amino acids
  • There are 20 different amino acids
  • When amino acids are joined together a protein is formed
  • Amino acids can be arranged in any order, resulting in hundreds of thousands of different proteins
  • Examples of proteins include enzymes, haemoglobin, ligaments and keratin
• Protein shape


  Different proteins have different amino acid sequences resulting in them being different shapes
• Even a small difference in the amino acid sequence will result in a completely different protein being formed
• How different protein shapes are formed


  1. Different sequences of amino acids cause the polypeptide chains to fold in different ways

  2. This gives rise to the different shapes of proteins
• Every protein has a unique 3-D shape that enables it to carry out its function
• Relationship between protein shape and function


  The shape of a protein determines its function
• Enzymes


  • Have a specifically shaped active site
  • This is where a specific substrate molecule fits in order for a reaction to take place
• If the shape of the active site does not match the shape of the molecule that fits into it


  The reaction will not take place
• Antibodies


  • Proteins produced by certain types of white blood cells that attach to antigens on the surface of pathogens
  • The shape of the antibody must match the shape of the antigen so that it can attach to it and signal it for destruction