Figure A  represents a bacterium cell with a single circular DNA molecule containing all of its genes.  Note:  no nuclear membrane, chromatin  or nucleoli. 

 
   Figure B  represents a the bacterium cell after DNA replication. This process will be described in miniunit Delta.. 

 
     Figure C represents a bacterium cell after the two circular DNA molecules separate and the cell membrane begins to pinch the cytoplasm into two parts. 

 
     Figure D represents continuous pinching the cytoplasm into two cells. 

  
    Figures E and F represent two complete bacteria cells after binary fission. These two cells are genetically alike. 
 
 
             Viral Replication 
 

     Viruses reproduce similar to the bacteria except the DNA must first be injected into a living cell (prokaryote or eukaryote) where the DNA replicates and than forms more viruses inside the living cell. Read the pages indicated by G-8 concerning viral replication. Learn the following steps concerning  virus reproduction. (1) virus enters a cell by endocytosis, (2) virus DNA enters the nucleus, (3) viral DNA is copied many times (4) virus DNA is transcribed into mRNA which moves to cytoplasm (5) mRNA makes various virus  parts (6) viruses are assembled  into many complete viruses. (7) newly formed viruses leave the cell by exocytosis or destroying the living cell. Viruses  may also  have its DNA incorporated into the host chromosomes. The host cell may replicate by mitosis forming many cells with the viral incorporated DNA. At a later time the viral genes may be transcribed into mRNA which produces more viruses. In your notes write the differences between a virus and a bacteriophage.  Draw two figures in your notes showing bacteria and viral replication. 
 
 

               Bacteriophage: 
 
 

1. Viruses reproduce by binary fission outside of of living cells. 

          a) true                              b)  false 

Press here to check answer.   press 
 

2. Viruses will only attack only eukaryotic cells. 

          a) true                              b) false 

Press here to check answer.  press 
 
 
 
 
 
 
 
 
 
 
 
 
 
 

The correct answer to the question below will move you to the next page. 

3. Identify the statements below to one of the following processes: 

    A) mitosis  B) bacteria reproduction   C) viral replication    D) all three processes 

    1. Genes segregated via DNA  replication and segregation. 
    2. Consists of spindle fibers which pull chromosomes to opposite poles. 
    3. DNA must be replicated many times in a living host cell before forming new 
        organisms. 
    4. DNA replicates followed by the cell pinching the cytoplasm into two cells  each 
        of which contains one of the DNA molecules. 

                       1                        2                       3                    4 

            a)         C                       D                      A                   B 
            b)         A                       B                      D                   C 
            c)         D                       A                      C                   B 
            d)         D                       C                       A                  B 
 
 
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