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Post by lauren on Apr 23, 2012 19:21:34 GMT -5
Hi Miss, Do we have to know about microsatellites and telomeres? Thanks.
No. Only what we did in class.
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seema
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Post by seema on Apr 23, 2012 19:29:22 GMT -5
Thanks Lauren, that makes sense!
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seema
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Post by seema on Apr 23, 2012 19:29:41 GMT -5
Also, what is the purpose of the 5' cap?
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Post by lauren on Apr 23, 2012 19:48:01 GMT -5
Hey Seema, The 5' Cap is on the mRNA there so that when the mRNA ventures out into the cytoplasm it doesn't degrade and break down. It's sort of like a protection for the mRNA and it is also recognized by protein synthesis machinery. Happy Studying!
Actually, that is the only part of the reason. The main reason for the cap is to help the ribosome find which end to start at. The 5' cap will be followed by the start codon thus thr ribosome will start at the cap instead of the tail.
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Post by anjali on Apr 23, 2012 20:02:35 GMT -5
Hello, in our notes it says that there are 3 tRNA binding sites on a ribosome. If two sites are the A and the P site then what is the third site?
Yes it is true there are three sites, but for the purposes of this course, we only talked about the two more important ones in depth.
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seema
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Post by seema on Apr 23, 2012 20:19:25 GMT -5
Hey Miss, I don't understand what it means by the "large ribosomal subunit" and the "small ribosomal subunit". More specifically, when it says "First 2 codons of mRNA bind to large ribosomal subunit • tRNA brings Met to AUG sequence of mRNA • Small ribosomal subunit binds"
Is AUG one of the first two codons? This part just really confused me!
Okay there are two subunits to one ribosome: a large and a small. The mRNA gets sandwhiched between them . The first two codons (AUG is always first, and then whatever codon happens to be next), will bind to the ribosome. AUG codes for methionine so the tRNA corresponding to AUG will deliver methionine to the AUG. The tRNA corresponding to the next codon will bring that amino acid. These two amino acids will create a peptide bond. The AUG tRNA will then leave. The second codon will move over to the P site. The next codon (the third codon) will now move into the A site. The tRNA will bring the amino acid. A peptide bond will form between that amino acid and the one from the second codon.
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Post by rebeccabarnard on Apr 23, 2012 20:32:10 GMT -5
slightly confused... using the digestion of lactose as an example, how do prokaryotic cells, such as bacteria, regulate structural genes?
When lactose is NOT present, the cell does not need to be able to digest lactose thus the genes which code for the enzyme which digests lactose are not being transcribed (turned off). This occurs because a repressor molecule attaches itself to the operator site (located between the promoter region and the genes which code for the lactose digestive enzyme). When the repressor binds to the operator, the RNA poly II is blocked. It physically can not move along the DNA which means it can't get to the genes in order to transcribe them. No transcription means no digestive enzyme is produced.
When lactose is present, the cell needs to be able to break it down. So the genes which code for the digestive enzyme must be on (being transcribed). The lactose acts as an inducer. It binds to the repressor molecule and changes it shape. Now the repressor can no longer bind to the operator (this of two puzzle pieces where you cut off part of one...now they don't fit because the shape changed). Since the repressor is not bound to the operator, RNA poly II can go through, move along the DNA and transcription will occur.
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carly
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Post by carly on Apr 23, 2012 21:12:44 GMT -5
During initiation of transcription, what does it mean by 2 codons of mRNA bind to 'large ribosomal subunit'? What is this subunit? Does it differ from the tRNA?
Carly, I think my aswer two posts up answers your question as well.
Okay there are two subunits to one ribosome: a large and a small. The mRNA gets sandwhiched between them . The first two codons (AUG is always first, and then whatever codon happens to be next), will bind to the ribosome. AUG codes for methionine so the tRNA corresponding to AUG will deliver methionine to the AUG. The tRNA corresponding to the next codon will bring that amino acid. These two amino acids will create a peptide bond. The AUG tRNA will then leave. The second codon will move over to the P site. The next codon (the third codon) will now move into the A site. The tRNA will bring the amino acid. A peptide bond will form between that amino acid and the one from the second codon.
Does this make sense or do you want me to explain it further?
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carly
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Post by carly on Apr 23, 2012 21:37:16 GMT -5
ok makes sense, I will look over the note again thanks.
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Post by melanie on Apr 28, 2012 16:25:22 GMT -5
Hello Miss Di Federico, I was starting the biotech pamphlet assignment and read that you want us to cite APA Style. I was wondering if you had time to quickly explain how to do this. We have never cited with APA Style before and I want to make sure that I get it right. Also, would you like us to cite all the way throughout the pamphlet after every piece of information that we collected or could we just make a references page at the end?? Thanks & Have a Good Weekend Don't site all the way through. Your pamphlet will just end up looking messy. Instead, have a section (probably on the back) where you list your resources like a works cited page). APA style formatting can be found at:
library.mcmaster.ca/guides/apa-style-guide ** click through to the tab you want**
I didn't mean to through something new at you but I just figured since you will have to do APA referencing next year, you should at least use it a little bit now.
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carly
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Post by carly on Apr 29, 2012 7:51:44 GMT -5
Hi, I have the same question, do we need to cite within the pamphlet, or just in works cited?? Thanks
On the back of the pamphlet would be fine. Think of an info pamphlet that has a list of "further information" on the back. Know what I mean?
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carly
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Post by carly on Apr 29, 2012 8:13:19 GMT -5
Also, for the question.. What is biotechnology/genetic engineering you are just looking for the definition of one of those right? Not both? So if I was doing stem cells I would probably define biotechnology instead of genetic engineering because it applies more to my topic?
Yes. Pick whichever applies more to your topic.
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Post by anjali on Apr 29, 2012 9:57:37 GMT -5
Hi Miss, I was wondering what the purpose of making recombinant DNA is because i am reading over the notes and it seems like you are just removing a sequence of nucleotides from one DNA molecule and then replacing it with the same sequence that has been taken out of a different DNA molecule. What is the point of this? Is the purpose of this just to show us that the same DNA sequence from one organism will preform the same function if it is inserted into another organism? Also, when we are talking about plasmids and bacterial cloning are the new plasmids that are created also considered recombinant DNA?
The point is to make a bunch of copies of a piece of DNA. So let's say you have a gene and you want to figure out the sequence (what order the bases are in) so you can compare it to the sequence of a mutated form of the gene (which bases have been added/deleted/changed). You are going to need more than one copy of that gene so you can do tests on it to find the sequence. We don't really get to talk about how you would sequence a gene in this course, but just know it can be done and you need many copies of the gene to do it. If that gene is in a human cell, you can take one cell, break it open, splice out the gene and insert it into a plasmid. You can then take that plasmid, put it in a bacterial cell and let that cell divide. After the cell divides 100 times, you now have 100 copies of the gene you are interested in. So now you can burst open the bacterial cells, and extract the gene you want (again, we don't really talk about how to do this in this course). Now you have 100 copies of the gene and you can do experiments on the gene. Yes, as the plasmids replicate, they are still considered recombinant DNA since the DNA in the plasmid originated from two different sources. The only difference is these replicated plasmids are clones of the original plasmid that was constructed in the lab and inserted into the bacterial cell.
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Post by Miss DiFederico on Apr 29, 2012 12:51:46 GMT -5
Hello everyone, I have a question for you this time.
Since I will not be here for homeostasis and population dynamics, would you like me to post some notes anyways? I know a few of you have sad you like my style so I was thinking this may be of assistance to you. The notes I would be posting are my old study notes from high school (I haven't had a chance to teach these units yet so I don't have slides made up like I use for class). I have no problem scanning them so anyone who wants them can have a copy. It's just my scanner takes forever to work so I figured I would check to see that at least one person wants them before I set out to do the scanning.
So my question is: to scan or not to scan?
Let me know what you think.
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Post by sarahb on Apr 29, 2012 15:08:33 GMT -5
scan!! that would be so helpful ms and im sure everyone agrees Okay will do. I'm not sure if I'll get around to it this weekend, but definately by the end of the week.
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