anyone with some free time... can you answer some questions about this lab report

alleyez

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I have to write a lab report.... for my bio class. Has anyone written the lab report for the fruit flies experiment? Drosophila melanogaster
I really need some help

Please let me know if you have some free time.. I just have some specific questions concerning this lab report.

Sorry for posting this in the pre-allopathic forum.
 

Fish3715

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Originally posted by alleyez


Sorry for posting this in the pre-allopathic forum.

Well, these are the right people to ask. I asked them a question about my chemistry lab yesterday.
 

Mediculous

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What specifically do you need help with? Your post was pretty ambiguous, as if you were addressing people in the same class as you. Are you in a Intro Bio class or a genetics class? Tell me what specifically you need help with and I'll try to help.
 
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alleyez

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Originally posted by Mediculous
What specifically do you need help with? Your post was pretty ambiguous, as if you were addressing people in the same class as you. Are you in a Intro Bio class or a genetics class? Tell me what specifically you need help with and I'll try to help.

this is for bio 2


do you use AIM? it would be much more helpful if i can ask the questions on aim
plus i don't want to cloud up this board with questions no one cares about :laugh:
 

alleyez

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Here are some of the questions I have... the questions might be vague in some ways because I don't fully understand the experiments we carried out. (missed a lab which threw me off from the start)

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my main concern is the data and discussion of the results.
For the data... is it safe to just complete the chi square and include that in the lab report? Should I include anything else for the data section?

for the discussion, what are we supposed to discuss? I know i can discuss whether the hypothesis was correct, etc....
I can talk also about whether the model crosses were autosomal linkage, sex linkage, or independent assortment.. but what else? How do I further support the hypothesis?

The results and discussion section is my main concern. If you can go beyond what I'm asking.. and supply more detail, it will be greatly appreciated. Any examples would be very helpful too.




One last question... for the introduction, what sort of background info should i include?
I had it checked over with the TA.. and he left me some notes on the sides... but didn't give me any guidance. If you can break the info I should include in the introduction into parts.. that would be very helpful too.



The rest of the lab report... I think I can manage. The results, introduction and the discussion of the results are what worries me.


thanks for your time.

Please let me know if you need a clarification on some of the questions....
 

Mediculous

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Ok, first, for the intro, I would include a brief background on why the fruit fly is a model organism to study genetics(short life cycle, tons of offspring, etc.). Then I would include references to papers that discuss the traits you studied. For example, if eye color was a trait you examined, then punch in the specific eye colors you encountered in a journal search engine and pick out what you think has relevance. By relevance I mean is the trait associated with increased fitness, or decreased fitness, etc.. You should also talk about what data you would get if your hypothesis was to be supported. This should be the majority of your report. You are carrying out experiments that were being published before your professors were probably born, so just put down a good line of thought as to why any of the data you collected is relevant.
For the data, include your chi-square test(s) (multiple, most likely, as you need to do one seperately for males, females, and all). Also include the p-values and degrees of freedom. Then in your discussion talk about why your hypothesis was falsified/supported based on the p-values.
For your discussion, of course talk about your hypothesis and whether or not it was supported. Most likely, your hypothesis shouldn't be supported. Then talk about the genetic system that you think is responsible in your fruit flies, then why you think that, and then what kind of experiment could support your hypothesis along with the expected results from that experiment that would support your new hypothesis. For example, think about linkage, sex-linkage, along with the number of alleles involved, and the type of assortment that may be going on. The most likely proposed experiment will be a testcross, but it may not be in your case. If, by some chance, your original hypothesis is supported, discuss the implications of the genetic system your flies have, and if further experiments could lend support.
Ok, that's it, and I have to leave work now, so good luck!
 

TTSD

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Not sure what your question is.. it seems like you're having difficulty with the format of your lab report?

A lab report is written a lot like a journal article:

<Abstract: depends on whether your TA wants one or not>

1) Introduction:

A brief overview of what you are studying including some background information.
The Question(s) you are answering.
Your hypothesis.
And one or two sentence that sums up what you found.

2) Materials/Procedure:

Here you will talk about the materials you used and the procedures used to carry out your experiment. Pretty straightfoward. Ever do the "Peanut and Butter Jelly Sandwich Procedure" exercise? Pretty much like that, be as thorough as possible so the person reading can do the experiment exactly as you did.

3) Results/Data:

This is where all your math comes in. For lab reports you should also include raw data. Show how you got your concluded numerical data. Chi square tests (p<.005). SHOW ALL YOUR WORK!

4) Conclusion/Discussion:

This is where you bring it all back together again. Was your hypothesis correct? How does your data show it? If not, why isn't it correct and what do you believe is going on. Are there any considerations that you have to take into account that could have affected the data?

Hope that helps. If you have any other questions, just ask.. I'm thinking you had some specific questions on Drosophilia.. but you didn't post 'em.
 

exmike

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its pretty much halfway through the second semester and you're doing your first lab report?
 

alleyez

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Originally posted by TTSD
Not sure what your question is.. it seems like you're having difficulty with the format of your lab report?

A lab report is written a lot like a journal article:

<Abstract: depends on whether your TA wants one or not>

1) Introduction:

A brief overview of what you are studying including some background information.
The Question(s) you are answering.
Your hypothesis.
And one or two sentence that sums up what you found.

2) Materials/Procedure:

Here you will talk about the materials you used and the procedures used to carry out your experiment. Pretty straightfoward. Ever do the "Peanut and Butter Jelly Sandwich Procedure" exercise? Pretty much like that, be as thorough as possible so the person reading can do the experiment exactly as you did.

3) Results/Data:

This is where all your math comes in. For lab reports you should also include raw data. Show how you got your concluded numerical data. Chi square tests (p<.005). SHOW ALL YOUR WORK!

4) Conclusion/Discussion:

This is where you bring it all back together again. Was your hypothesis correct? How does your data show it? If not, why isn't it correct and what do you believe is going on. Are there any considerations that you have to take into account that could have affected the data?

Hope that helps. If you have any other questions, just ask.. I'm thinking you had some specific questions on Drosophilia.. but you didn't post 'em.

thanks.. yeah I do have specific questions on Drosophilia. I asked my TA for help but he didn't give me any guidance.. I had no clue what he was talking about.. about the p value, and all this other statistics stuff.... he seemed like he was in a hurry so I didn't want to get in his way.

Can someone explain the p-value, Ho, Ha, etc

for instance, from the results of the p-value, how do I incorporate that value into my discussion? What do I say about it?
I have so many questions i dont even know where to start.. so pretty much, if you know what I should include, please say anything and everything about what you know.

I'm just going section by section and trying to work this through.
I'm still trying to finish the introduction.

thanks for all the help guys.
 

TTSD

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Well, assuming you know how to do the Chi-Squre test..

Which should be the SUM of the (Observed-Expected)^2/Expected. If that is less than .05 for one degree of freedom (or 3.84 equivalent).. then your hypothesis is correct. It could NOT have arisen by pure chance and that there is a significant statistical correlation in the data you see.
 

docmemi

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make sure your results section has words/a paragraph saying what the results are and what the tables mean. in other words, make sure there are some sentences there as well. dont just put a table and numbers and not explain them. dont draw conclusions here, but just say in words the meaning.
 

alleyez

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is it safe to hypothesize that both model crosses will assort independently thus forming the 9:3:3:1 phenotypic ratio?
 

TTSD

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Originally posted by alleyez
is it safe to hypothesize that both model crosses will assort independently thus forming the 9:3:3:1 phenotypic ratio?

..dude.. stop speaking in like half-thoughts. I have NO idea what model you're talking about and therefore don't know WHAT phenotypic ratio you're talking about. Biology is not THAT standardized across the United States.

Drosophila is WIDELY used as a genetic model because it:
a) Breeds FAST
and
b) It's genome is pretty much mapped out.

You gotta tell us MORE if you want SPECIFIC questions.
However, I'm guessing you're probably either talking about eye color or wing span as those two are the most oft-looked at in intro classes in regards to genetic inheritance.

One thing in science you should NEVER EVER EVER EVER do! DON'T EVER ASSUME YOUR READER WILL KNOW WHAT THE HECK YOU'RE TALKING ABOUT! Take that into account when you write your report.

When you say, "Anyone do the drosophila experiment?" There's been thousands of experiments done on various parts and systems of that small fly. Which one are you referring to?

When you say, "Can I cross the modesl?" There are thousands of models. Which one are you speaking of?

When you say, "9:3:3:1 Phenotypic ratio." Ratio of WHAT? Crossing of what?
 

alleyez

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well sorry about that TTSD... that question wasn't that relevant anyways. Please ignore it.



Could you please explain more about the chi square?
(observed - expected)^2/expected ---> (o-e)^2/e

the sum of all the values for that equation is x^2 correct?


what goes in Ho and Ha?

i got the x^2 part.... i also have the degree of freedom....
but how do i calculate the range of the p value?

I hope these questions are specific enough... let me know if otherwise

thanks
 

carrie198

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Originally posted by alleyez
well sorry about that TTSD... that question wasn't that relevant anyways. Please ignore it.



Could you please explain more about the chi square?
(observed - expected)^2/expected ---> (o-e)^2/e

the sum of all the values for that equation is x^2 correct?


what goes in Ho and Ha?

i got the x^2 part.... i also have the degree of freedom....
but how do i calculate the range of the p value?

I hope these questions are specific enough... let me know if otherwise

thanks

Maybe you've already written the paper, but if not, here's my input: you need to look at a Chi Squared Table. There should be one in your textbook or find them online. You don't calculate the p value. You determine it by looking at the table. You stated that you know the degrees of freedom, so once you determine the chi squared number, you just look on the table to determine the p-value. Here is a good link to explain this:

http://www.colorado.edu/MCDB/MCDB2150Fall/notes00/L0023.html

Also, make sure that when you write your materials/methods section, you write paragraph form, in the third person past tense. Don't say, "first I added ______, then I did _______" Blah, blah, blah. Don't say "add _______ to ______", etc. Also, don't write out every single step of your procedure. See a scientific paper for an example of how to do this.

I hope this helps!
 
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