Name____________________________________ Date________________ Hour________________

GENETICS COMPUTER SIMULATIONS – DIHYBRID CROSSES

GENETICS CD – 6

Directions: Obtain a CD entitled "Biology Explorer 3.04 Genetics" and a coin from your instructor. Go quietly to the Media Center computer lab. Insert the CD and then complete the following activity. Return the CD to your instructor when finished.

PURPOSE: To investigate a simulated cross where two traits are followed at one time.

PROCEDURE:

    1. Go to the START MENU.
    2. Place your cursor on PROGRAMS.
    3. Move your cursor to "LOGAL Biology Teacher."
    4. Click on GENETICS MAIN MENU.
    5. Click on "CORE INQUIRIES."
    6. Click on "DIHYBRID CROSSES."
    7. <<At this point, the arrows to move around through the program are at the very bottom of the screen. We may have to grab and drag the Start menu tool bar downward until we can’t see it any longer in order to uncover the arrows we need.>>
    8. Follow the directions on each page to complete the exercise. Blue "hyperlinked" words in the directions text can be clicked on to perform certain functions.

QUESTIONS AND DATA TABLES:

  1. Data table one:
    2.

    EXPECTED PHENOTYPE

    OBSERVED PHENOTYPE

    1. COUPLE #1

    2. COUPLE # 2

    3. #1 MALE AND #2 FEMALE

  2. Data table two:

    3. Based on these crosses, write which trait variations are dominant and recessive.

    DOMINANT

    RECESSIVE

    EYE COLOR

    A:

    a

    WING COLOR

    B

    b

  3. How many different phenotypes are possible?_____________________
  4. What are they?

    5.  

     

     

     

  5. Data table three:
    6.

    PHENOTYPE

    NO. OF OFFSPRING

    PHENOTYPIC RATIO

    EYE COLOR

    WINGS

    RED

    CLEAR

    RED

    SPOTTED

    WHITE

    CLEAR

    WHITE

    SPOTTED

  6. What is the difference between these new parents and those in the first F1 x F1 cross?

    7.  

     

     

  7. Data table four:
    8.

    PHENOTYPE

    NO. OF OFFSPRING

    PHENOTYPIC RATIO

    EYE COLOR

    WINGS

    RED

    CLEAR

    RED

    SPOTTED

    WHITE

    CLEAR

    WHITE

    SPOTTED

  8. In both F1xF1 crosses, each parent has the same genotype. What is this genotype?____________________________-
  9. What is the difference in the results between the first and the sencond F1xF1 crosses?

    10.  

     

  10. Sketch the chromosomes and genes of the parents in each cross.

    11.  

     

     

     

     

  11. List the possible genotypes of the sex cells for each set of parents.

    12.  

     

  12. Use Punnett squares to determine the expected phenotypes for each cross and their ratios.

    13. DO THESE PUNNETT SQUARES ON YOUR OWN PAPER AND STAPLE THEM TO THIS SHEET.

  13. What can you conclude about the phenotypic ratios of F1xF1 dihybrid crosses if the two genes are linked on the same chromosome?

    14.  

     

     

  14. If the genes are on different chromosomes?

    15.  

     

  15. What are all the possible genotypes for individuals with this phenotype?

    16.  

  16. Suggest a plan to distinguish among these different genotypes. (REPHRASING THE QUESTION – What would need to be crossed with a red eyed/clear winged fly to test to see if it were homozygous dominant or heterozygous?)

    17.  

     

     

  17. Data table five:

THREE TEST CROSSES WILL BE PREFORMED!

ID NO. OF SUBJECT

PHENOTYPES AMONG OFFSPRING

PHENOTYPIC RATIO

GENOTYPE OF SUBJECT