B3 Part I

B3 Part I

1. Molecules of Life

   • Mitochondria
     • Tiny structures found in the cells. Respiration occurs here
     • Respiration-Releases energy from glucose
     • Tissues/organs have large numbers of it e.g. liver and muscle cells
   • Ribosomes
     • Can be seen with electron microscope
     • Found in the cytoplasm and are in the site of protein synthesis
   • Chromosomes
     • Cells nucleus contains chromosomes
     • Long coiled molecules of DNA
   • DNA
     • The information contained in genes is in the form of instructions called genetic coding
       • Genetic coding controls cell activity, meaning it controls some characteristics of the organism
     • Controls the production of different proteins
       • Needed for growth and repair of cells
     • Structure
       • Two chains wound into a double helix
       • Each strand is made of chemical bases
         • G-C-A-T
           • Base pairs G-C and A-T
       • Two strands coil together to form a double helix
         • With chemical cross links between the two strands , formed by pairs of bases
     • Genes and proteins
       • contains a different sequence of bases and codes for a particular protein
       • Proteins are made in the cytoplasm
       • Genes cannot leave nucleus
         • Copy is made which is able to leave the nucleus
       • Making proteins
         • G-C-A-T
         • Protein structure is determined on Base Codes
         • Each amino acid coded by sequence order of three bases
         • mRNA(messenger RNA)
           • Copied DNA is carried by mRNA
             • mRNA from DNA = Transcription
             • Proteins from mRNA is called translation
     • Controls the function of a cell by controlling its production of proteins
       • e.g. enzymes

2. Proteins and mutations

   • Proteins
     • Polymers
       • Large molecules made from many smaller molecules
     • Each protein molecule built from amino acids
       • which are smaller monomer molecules
         • Join end to end making protein polymer molecule
     • Each protein has own number of sequence of amino acids
       • Gives the protein a particular shape allowing a particular function to be carried out
     • Types of protein
       • Structural = Collagen
       • Hormone = Insulin
       • Carrier molecule = Heamoglobin
       • Enzyme = Amylase
   • Enzymes
     • Biological catalysts
       • speed up chemical reactions
     • Catalyse chemical reactions in living cells
       • Respiration
       • Photosynthesis
       • Protein synthesis
     • Active Sites
       • Shape determines how it works
       • active sites are where the substrate molecules fit into when the reaction happens
         • Substrate molecule - a substance on which the enzymes react
       • Has to be right shape for the substrate molecules to fit into
         • enzymes have high specificity for their substrate
           • A particular enzyme with particular substrates
     • Temperature
       • At low temp enzyme reactions are slow
       • Reaction speeds up as temp rise until an optimum temp is reached
       • After this point the slow down and eventually stop
       • Steady increase between 0-40'C ussally optimum is around 40
     • pH
       • optimum pH like temp
   • Mutations
     • Spomtaneous
     • Happen because of
       • Radiation
       • Chemicals such as tar from cigarette smoke
     • Harmful or Helpful
       • Often harmful
     • Genes can be switched on and off
       • mutations can alter the production of certain protiens
   • Changing shape of the active site will cause reaction to slow
     • Eventually the reaction will stop
       • Enzymes become denatured
   • Q10 = measure of the rate of change of a reaction when the temperature us uncreased by 10'C
     • Many of Q10 of 2
     • Q10 = rate at higher temperature / rate at lower temperature

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