D.               Changes in Genes ANSWERS

           
    Changes in genes are passed
    on to subsequent generations
    of  C E L L S  (definitely NOT pictured)

                by the process of  M I T O S I S. 
      (pictured on the left)

 

(1)     

             Any change of the DNA sequence is
        known as a  M U T A T I O N.  
        Usually, a changed gene will be passed
        on to every cell that develops from it.

(2)     

People therefore think that all future generations of cells ...

    

        made by the process of  M I T O S I S 
   (pictured on the left)  from this altered
   cell would have to be  (different/ alike)
    __ALIKE__.

 

(3)   Surprise!   This is usually, but not always the interesting case.  
                The many body cells in an individual can be very D I F F E R E N T
                from one another, even though they are all descended from a
                S I N G L E  cell, created by the cellular process of  M I T O S I S
                and thus have  I D E N T I C A L  genetic instructions. 

      This is because different parts of these  D N A  instructions are used in
                different types of cells (more information), and are influenced by the cell’s
                environment and past history.

(a)        A white blood cell will only use those genes which tell it how to
    function as a  __WHITE__ cell.    That's the big cell in the middle
    surrounded by red blood cells.

 

 

(b)      A skin cell will only use those genes which tell it how to function as a
       __SKIN__ cell.

(c)    

(c)   

            A liver cell will only use those genes which tell it how to
        function as a __LIVER__ cell.

 

 

(d)                                                        

            As time goes by, cells start to  D I F F E R E N T I A T E  into
       different cell types such as blood cells, skin cells and liver cells.

 

           Cell Differentiation