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45 lines
2.0 KiB
Markdown
45 lines
2.0 KiB
Markdown
---
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cards-deck: default_obsidian
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---
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#bio
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# short tandem repeat
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#card/reverse
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repeating patterns found in dna. Using the number of instances that a small sample is repeated can be used for dna analysis in order to figure out crime scenes and such.
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^1654056403856
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# replicating dna
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## semiconservative model
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idk, seems like the legit way that dna is actually replicated, as opposed to the conservative model and the dispersive model. looks like ![[Pasted image 20220531221547.png]]
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primase ::: molecule primer, initiates the construction of new dna. creates rna primer. ^1654057167325
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DNA polymerase ::: an enzyme for making dna. uses primer and parental dna to match up new dna nucleotides to make a new dna strand. ^1654057167331
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helicase ::: unzips both sides of the dna molecule. You can only go from 5' to 3'. only in one direction.
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- leading strand goes in the right direction
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- lagging strand has to go back and forth, since it's backwards.
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## thermal cycler
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ingredients for lab dna reading in a thermal cycler.
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- h20
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- dna
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- primer
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- nucleotides
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- polymerase
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the cycler heats the dna up to get it seperate, then cools it down in a cylce that does a great job of breaking stuff up and letting you exponentially copy the dna.
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You can just sequence the dna like in STRs, or you can put it in an agar gel, and turn on an electric charge. Short fragments go fast, long dna goes slow.
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## dna difference detection.
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You have to cut the dna into different fragments by using a tool to cut at molecular palindromes. ![[Pasted image 20220531223334.png]]
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Some dna is cut differently, like so:![[Pasted image 20220531223415.png]]
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You'll see dna like this: ![[Pasted image 20220531223446.png]]
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You can thus see that the dna is different. The suspect has a really short piece that the crime scene dna doesn't have.
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The scissors are called restriction enzymes. The analysis used is called
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RFLP ::: Restriction Fragment Length Polymorphisms, you're looking for palindromes, where either side of the dna is the reverse of the other.
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