Practice - Nucleic Acids 2 - Video Tutorials & Practice Problems
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Practice - Nucleic Acids 2
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Shar Gaps rules tell us that the amount of purines in double stranded DNA is gonna be equal to the amount of pyrimidines. And that's because there's 50% of each. And, additionally, they tell us that the amount of adenine is going to be equal to the amount of theanine, because they're always going to be bound together. And, the amount of cytosine is equal to the amount of guanine because, again, they're always going to be bound together. And these are basically summed up by answer choice e. Now the Watson Crick model of DNA does not include, D, 2 equally sized, grooves running up the helix. And, you might recall that there is actually a major groove that is larger than the minor groove as the names imply. And, recall also that the major groove is generally where, proteins, bind into DNA, though some do interact with minor groove. Question 8, which of the following is a palindromic sequence? This basically relies on you knowing what the term palindrome means, and that's something that is the same written backwards and forwards. Like, the word kayak or radar, you could write it backwards or forwards, and it would be exactly the same. So looking at our answer choices, answer choice d is the correct answer here. And if you look at those 2 sequences, ggatcc and ggatcc, you'll probably notice that, they're the same sequence written backwards and forwards. And, actually, I hope you noticed that the 5 prime end is the same on both, and the 3 prime end is the same on both. Because remember, DNA's structure is anti parallel. Alright. Take a moment, pause the video, do number 9. I've actually already drawn the structure out because it is quite large. And, I don't want to spend a lot of time drawing the structure out in front of you because that's boring. So, what I do wanna quickly go over is the numbering here on the molecule. Let's start with our base. Right? This is our base molecule, and it is numbered starting at this nitrogen 1, 2, 3, 4, 5, and 6 there. Now let's take a look at our sugar. And that is number 1 prime, 2 prime, 3 prime. Notice how because this is deoxy, we don't have no Oh on the 2 prime. So there's our 4 prime, 5 prime. That is where the phosphate's attached, and c t p, that is t for tri. So triphosphate 3 phosphates, and we have them 1, alpha 2, beta and 3 right here is our gamma. Alright. So that is our, deoxycytosinetriphosphate. Let's flip the page.