What Are The Factors That Determine Phenotype Ii.doc by lizzy2008


									                 THE FACTORS WHICH DETERMINE AN
                              ORGANISM’S PHENOTYPE
PROKARYOTES               PROTOCTISTS FUNGI                     PLANTS                ANIMALS
Cell Biology              Biochemistry Physiology               Genes & Genetics      Ecology
Gas Exchange &            Nutrition    Homeostasis &            Coordination &        Reproduction &
Transport                              Excretion                Movement              Growth

Cell       Biochemistry                   Physiology              Genes &            Ecology
Biology                                                           Genetics
           Enzymes coded for by genes     determined by           genes inherited    Environment
           determine chemical             genes& adapted by       from parents via   affects phenotype
           reactions which affect how     natural selection -this meiosis            e.g. size of limpets
           an organism looks e.g.         affects phenotype       genes contribute
           pigments                       exchange surface        to 'genotype' &
                                          limits size             so affect
                                          transport of gases      phenotype
                                          limits size + shape

Intro: phenotype=characteristics of organism we see or detect
                =affected by (1) genotype
                              (2) environment, & their interactions with one another.
                =e.g. height, eye colour, ABO blood group, presence or absence of cystic

Para 1: Enzymes coded for by genes determine chemical reactions which affect how an organism looks
or works e.g. pigments. Lung protein in cystic fibrosis.

Para 2: genes inherited from parents via meiosis, contribute to genotype & so affect phenotype.

Para 3: Interaction of genes e.g. blood groups

Para4: Environmental effects: as organism adapts to suit environment better, via natural selection,
phenotype (size & shape) changes. E.g. limpets Hence effect of environment.

Para 5: food source available in environment affects phenotype, e.g. protein needed for tissue &
        cell growth, so more protein available, more probably taken up by organism, greater
        growth. Link this to digestive enzymes organism has (dependent on genes), this limits
        ability to use nutrients & so affects efficiency & growth.

Conc: summary of environmental factors & genotype effect on phenotype. Importance of lots
      combinations of genes as expressed in phenotype-variation-population more likely to
      survive disease etc..

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