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Fruit Fly Drosophila melanogaster experiment

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Presentation on theme: "Fruit Fly Drosophila melanogaster experiment"— Presentation transcript:

1 Fruit Fly Drosophila melanogaster experiment
AP Biology – 2018 Lab Dihybrid Cross and Sex-linked cross

2 Find a buddy for the fruit fly experiment
Go pick up two vials, two foam caps, two stickers and place them on your vial in the center of your vial Watch your teacher demonstrate how to make a vial with media Make a vial with media, don’t forget to put only about 4-5 grains of yeast on the top of the media. 3. Now pick up a booklet of fruit flies and read the pages indicated until your teacher has you come up to get your flies and put them in your jar. Before you put them in your jar. Look at them under the microscope. Make sure to write the NUMBER of each of your males and females on your jar and which have white eyes and which have wild(red) eyes.

3 Take a booklet on Fruit flies and read/take notes on
Page 8, and 9 Life cycle and anesthetizing – HOW LONG DO YOU LEAVE IN WAND of fly nap? IMPORTANT – sleep not death Page 11 sexing and look at back of pamphlet Look at page 15, 16 and 17 on phenotypes Skim through the rest of the booklet to look at types of crosses and other information about Drosophila

4 Let’s look at a fruit fly cross
x Wild eye, vestigial wing Sepia eye/wild wing P1 F1: all wild F2 are all: 9:3:3:1

5 Get your fruit flies and your booklet
Take out a sheet of paper to record your data for your fruit flies Male red Male white Female red Female white Create a chart and use tally marks.

6 Sex-linked cross Wild eyes vs. White eyes
Parents XRXR x XrY or XRY x XrXr F1 Cross What is expected?

7

8 Male vs Female

9 Determining sex Female notice clear bottom, larger Male Dark end
On bottom

10 Class Results of Red eyed fem and white eyed males
Group Name Parents were Cross of Red eyed females with white eyed males XRXR x XrY Red eye female Red eye male White eye female White eye male Wk 1 Wk 2 Jade/Noah/ Sean 16 24 17 20 Abby/Reece 14 26 13 33 Liz/Skylar 15 79 56 Trinity/Raygen 18 30

11 Class Results of Red eyed females and white eyed males
Parents are cross of White eye female and red eye male XrXr x XRY/XrY apparently white eye males got in here  Group Name Red eye female White eye female Red eye male White eye male Wk 1 Wk 2 Wk2 Brandon/ Jordan 1 10 2 22 20 17 Eleanor/Klay/ Lauren 8 4

12 Dihybrid cross F2 results Tally your marks then share results
Group Name Red eyes, wild wing Red eyes, vestigial wing Sepia eyes, wild wing Sepia eyes, vest wing Day 1 Day 2 Day 3 Reece & Abby 55 8 7 22 4 2 20 10 1 Brandon Jordan 34 5 14 11 9 3 Trinity Raygen 18 12 6 Klay Lauren Eleanor Liz &Skylar 35 19 Noah Sean Jade 49 17

13 Write up for Fruit flies: Focus on dihybrid but discuss the X-linked cross in your analysis/results, conclusion. Problem/Question: Will a dihybrid cross of sepia/vg mutant parents crossed with wild result in the expected ratio of 9:3:3:1 and meet the null hypothesis. Hypothesis: Yours – might be the the NULL hypothesis. Materials: Procedure: Data tables/GRAPH, Analysis/Results: Show your math for Chi Square Conclusion: Follow writeup directions for Conclusion(3 paragraph approximately.)

14 Now Conduct the Analysis:
To determine null hypothesis value take the total number of flies and divide by 1/16, 3/16, 3/16, 9/16 to get the expected

15 2018 RESULTS add all your x2 values
Phenotypes observed expected o-e (o-e)2 X2 Wild Red eyes/ normal wings Red eye Vg wing Sepia eye

16 How many degrees of freedom? #phenotypes – 1 = degrees of freedom,
look under the .05 column CHI-SQUARE DISTRIBUTION TABLE Accept Hypothesis Reject Hypothesis Probability (p) Degrees of Freedom 0.95 0.90 0.80 0.70 0.50 0.30 0.20 0.10 0.05 0.01 0.001 1 0.004 0.02 0.06 0.15 0.46 1.07 1.64 2.71 3.84 6.64 10.83 2 0.21 0.45 0.71 1.39 2.41 3.22 4.60 5.99 9.21 13.82 3 0.35 0.58 1.01 1.42 2.37 3.66 4.64 6.25 7.82 11.34 16.27 4 1.06 1.65 2.20 3.36 4.88 7.78 9.49 13.38 18.47 5 1.14 1.61 2.34 3.00 4.35 6.06 7.29 9.24 11.07 15.09 20.52 6 1.63 3.07 3.83 5.35 7.23 8.56 10.64 12.59 16.81 22.46 7 2.17 2.83 3.82 4.67 6.35 8.38 9.80 12.02 14.07 18.48 24.32 8 2.73 3.49 4.59 5.53 7.34 9.52 11.03 13.36 15.51 20.09 26.12 9 3.32 4.17 5.38 6.39 8.34 10.66 12.24 14.68 16.92 21.67 27.88 10 3.94 4.86 6.18 7.27 9.34 11.78 13.44 15.99 18.31 23.21 29.59

17 One more helpful hint as you writeup your lab
When reporting chi square data use the following formula sentence…. With degrees of freedom, my chi square value is , which gives me a p value between % and %, I therefore my null hypothesis. This sentence would go in the “results” section of your formal lab. Your explanation of the significance of this data would go in the “discussion” section of the formal lab.


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