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Bio 103, Lab 9, Mendel's Garden Revisited
One central piece of modern biology derived from Darwin's voyage to the Galapagos in the latter part of the 19th century. A second emerged, more or less independently, during the same period and resulted from the work of Gregor Mendel breeding pea plants and carefully observing the results. This work produced the first clear understanding of "laws of inheritance", and remains fundamental to most modern understanding of genetics. And it revealed a mechanism for generation of diversity above and beyond mutation.
In this lab you will be invited to participate yourself in making the kinds of observations and inferences that Mendel made. We will do so together studying not pea plants but fruit flies, and using not live animals (for which the studies would take weeks or months) but a computer simulation which is quite realistic in most important characteristics. The simulation, called FlyLab, is available to registered individuals (students in this class) at http://www.biologylabsonline.com.
After we've worked through some of the basic observations together, you should work in pairs to make observations yourself on some fly traits other than those we have explored together. Your task is to "make sense" of your observations starting with the basic ideas we develop together and adding whatever additional ideas seem necessary. Try and find some traits that yield unexpected results in a monohybrid cross, as well as some that yield unexpected results in a dihybrid cross. For the latter, be sure you have fully understood the behavior of each trait in monhybrid crosses first.
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Fly Lab
After going over some basic concepts as a class, we started doing our own experiaments. I first looked at purple eyes (PR) and dumpy wings (DP) individually and together, and the results were similar to the experiments that we did as a class, so I chose other traits. I tried a female that had no wings (AP) and was tan (T), with a wild type male.
Female (AP;T) with Male (+) Offspring:
Female (+): 487
Male (T): 586
In the first cross, all the males were tan and all the females were wild type. Then, I crossed the offsring:
+: 413
AP: 128
T: 376
AP;T: 127
I wanted to explore this more with the gender, so I tried the same two traits on a male with a wild type female
Female (+) with Male (AP;T) Offspring:
+: 1066
All of the offspring in the first round were (+). Then I crossed the offspring:
Female (+): 378
Male (+): 200
Female (AP): 111
Male (AP): 71
Male (T): 184
Male (AP;T): 50
I needed to look at the traits individually to make sense of this. I started with T, because that one seemed to be linked to sex.
Female (T) with Male (+)
Female (+): 486
Male (T): 484
Again, all the males in the first round were tan, and all the females were wild type. I crossed the offspring:
Female (+): 256
Male (+): 282
Female (T): 234
Male (T): 241
Then, I tried the same thing with a tan male.
Female (+) with Male (T)
+: 1016 (all offspring wild type)
Then, I crossed the offspring:
Female (+): 503
Male (+): 278
Male (T): 251
All the females were wild type, while half of the males were tan and half were wild type. I believe that T is and X-linked trait. When just the mother is tan, she will pass the trait to her sons because the only X-chromosome they get is from her, while her daughters will be tan (if the trait is recessive), because they also get an X-chromosome from their father (if he is wild type). When the offspring are crossed, because the male is tan and the females have one X from their tan mother, this generation would be even. When just the father is tan, none of his children will be tan, because he will not pass the X-chromosome to his sons, and his daughters get another X-chromosome. However, when the offspring are crossed, because the daughters got an X-chromosome from their tan father, they would pass this on to half of their sons.
Small wings
(wild type) (mini-wings)
1.148 : 1
fly lab
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TRIAL ONE:
Original parents: female: wild type, male: sepia (SE)
I made a punnett square and expected that one quarter of the second round of offspring would have sepia eyes.
Phenotype Number
Female: + 49
Male: + 48
F2:
Phenotype Number
Female: + 35
Male: + 44
Female: SE 17
Male: SE 12
My trial went as expected, the sepia eyes were clearly a recessive trait and gender didn’t seem to significantly impact the results.
TRIAL TWO:
I crossed four different types of traits in this trial, and I wasn’t quite sure what to expect. I thought that in the F1 maybe 1 quarter of the offspring would show recessive traits and in the F2, the offspring would be split into extremely small ratios.
Original parents:
Female: sepia, black bodied (SE, BL), male: bar eyed, cross veinless (B,CV)
F1:
Phenotype Number
Female: B 484
Male: + 479
Total 963
F2:
Phenotype Number
Female: + 147
Male: + 102
Female: SE 48
Male: SE 26
Female: B 148
Male: B 34
Female: SE;B 50
Male: SE;B 13
Male: CV 47
Male: SE;CV 12
Male: B;CV 104
Male: SE;B;CV 34
Female: BL 41
Male: BL 39
Female: SE;BL 16
Male: SE;BL 7
Female: B;BL 46
Male: B;BL 12
Female: SE;B;BL 17
Male: SE;B;BL 5
Male: CV;BL 14
Male: SE;CV;BL 9
Male: B;CV;BL 31
Male: SE;B;CV;BL 11
Total 1013
This trial did not run as expected, as in the first round of offspring all of the females had barred eyes, and in the second there was an equal number of non barred eyes to barred for females, while males rarely had barred eyes. Additionally females never received the cross veinless trait, while many males did. In the F2 the ratios where somewhat what I expected, however I was shocked to see how dominant the bar eyed trait was in females.
Mating flies
For my experiment, I wanted to see if the wild type is dominant in all the features, so I mated a wild type female to a male that that had different type of feature for each features (ex. Wild type female and yellow body male, wild type female and eyeless male, etc). What I found was that the wild type is dominant for all features EXCEPT Antennae, Eye Shape, and Wing Angle.
For the second part of my experiment, I mated a wild type female with a dichate angled male. The results showed that it was a 1:1 ratio of wild type and dichate angled. This told me that although the dichate wing angle is dominant over the wild type, a dichate wing angled fly has a heterozygous genotype (D+), since a homozygous genotype (DD) would result to all dichate wing angled offsprings.
Next, I mated two dichate wing angled flies, and it showed that the ratio of offspring was 1:2, wild type:dichate respectively. An explanation for the ratio being 1:2 instead of out of 4 is that one quarter of the offspring is DD, which may indicate lethal genes, and thus does not exist.
These results were similar when I mated two aristapedia (antennae) as well as two flies with different shaped eyes. This indicates that although these three features are dominant over the wild type, it does not mean that they are homozygous genotypes, but rather heterozygous. This phenomenon also tells us that there are such lethal genes that some offspring can inherit, which leads to death, such as sickle cell anemia in humans.
Dominance
This lab was extremely
This lab was extremely confusing. I understand that the purpose of the lab was to comprehend how, why, and what traits an organism receives from its parents. In this experiement we used an online lab program where we would design and combine different types of flies to then analyze what traits have been passed on from one generation to the other. I did my best to get a variety of results. What I seemed to get when I designed the female fly with curly wing shapes and purple eyes and the male with aristapedia antennas and star shaped eyes their offsprings (the majority of them basically 75 out of 103 were wild types (regular or normal types of flies). I tried the experiement 25 types and seemed to get the same results, that the dominat trait that seemed to be passed on from generation to generation did not really change and all offspings were wild types. In this case Mendel's 9:3:3:1 ratio, which is still somewhat confusing to me, I'm assuming really does not fit since none of the offsprings did not inherent one specific trait from neither the mother or father. Meaning that they were all consistent in their traits not showing any major diversity.
Lab 9
Kalyn Schofield
During our experiments today,
During our experiments today, we looked at different crosses of fruit flies and how those crosses compare to the typical results expected in Mendelian genetics. We looked at several different traits: curly wings as opposed to regular wild wings and starry eyes instead of regular eyes. One interesting factor we had to account for was that the original specimens used in the parent generation for both of these traits by the fly lab were heterozygous instead of homozygous for the trait. This was slightly confusing, as it gave us a 3:1 ration for both the F1 and the F2 generation. We came to this conclusion by looking at possible punnett squares for these crosses.
Aside from traditional Mendelian genetics, traits can be influenced in real life by several different genes, or even be expressed in divergent ways, such as co-dominance or incomplete dominance. We're unsure of whether this could be mirrored in the fly lab, but when we tried to look at star eyes in conjuction with purple eyes (a true-breeding trait), our F2 generation produced ver non-mendelian results. Our ratios were not the expected 9:3:3:1, but we couldn't find an obvious exploration. In the future, we would possibly like to explore if this could have been an example of a sex-linked trait as opposed to a gene following the law of independant assortment.
-stu and drich.
Anna Chiles, Jennifer
Dumpy wings
Today we looked at Mendelian Genetics and its application in regards to fruit flies. To begin with, we chose a trait that we wanted to explore. This trait was "dumpiness" of the wings. When tested, we found that the "dumpy" trait was consistent with the ratio we learned in class: 3:1. Next, we looked at the color of the fruit flies and chose ebony as our example. We also found that, when tested, the ebony trait was consistent with the 3:1 ratio. After concluding that these two traits were true breeding, we decided to create a dihybrid cross between them. We then found that when these two traits were combined, they were consistent with the 9:3:3:1 ratio we also learned about in class. During our experiment, we tried a variety of traits (yellowness, eyeless, etc.) but ultimately reported these traits because we are always striving to be less wrong. Our results were as follows:
-Lili and Terrible2s