DIP Episode 585 - 2025 USMLE Step 1 Free 120 Discussion Part 5a (Q41-45, super helpful for Step 2 and 3!)

Alright, welcome, my name is Divine, this is episode 585 of the Divine Intervention Podcast. In today's podcast we're going to be continuing the Step 1 free 120 series. So this is part 5, so let's jump into question 41, it says, an 11 year old girl is brought to the ED by her parents because of a one week history on breast enlargement. She has not had pain on Nepal discharge, she has asthma treated with inhaled or butlerol as needed. She does not smoke cigarettes drink alcoholic beverages or usually say drugs. She's at the fifth year percentile for height and weight, vital signs are within normal limits. Examination of the breast shows minimal enlargement under the areole and mild enlargement of the diameter of the areole, areole without Nepal discharge. No masses are palpated, there is scan pubic here. Which of the fluim best describes the sexual maturity reading for the species, right? So whenever the USML is used to term sexual maturity reading, they are pretty much talking about Tanner staging. And how do you use Tanner staging on the exam? Well, again, there is Tanner stages 1 to 5. The truth is usually on the USML is the focus mostly on 1 to 4 because 4 and 5 are kind of a wash, they're kind of the same thing. So Tanner, you know, I remember it with this numonic, you know, NBIAA, NBIAA, so the N stands for nothing. So Tanner stage 1, you have nothing. On really Tanner stages, all they measure are the breasts and the pubic and axillary here.

So Tanner stage 1, the N stands for nothing. No breast development, no pubic and axillary here. That's Tanner stage 1. Obviously that does not apply to this girl because she has some breast development, she has some pubic and axillary here development. So the B stands for basics, the B stands for basics. So you're starting to have the basics like some breast spot development, some pubic, some axillary here. Which is what this lady has. So we're going to go ahead and go with Tanner stage 2 for her. So that's Tanner 2. So what does the eye in my numonic stand for? My eye stands for increasing, increasing, increasing, increasing. So things are increasing, things are increasing, things are increasing. What do I mean by things are increasing? So you have more than the basics, things have started increasing. So you're beginning to have more pubic and axillary here. You're beginning to have more breast development. That's going to be sexual maturity, routine stage 3, right? Again, this person is literally just starting out. Just starting out with the basics. So it's going to be stage 2. Really 4 and 5 are kind of the same. You know, 4, you've kind of hit adult stage. 5, you're really at adult stage in terms of breast development and pubic and axillary here development. It's pretty much the same thing. So this lady, I'm going to go with sexual maturity, rating stage 2 because she's just starting off with the basics. All right.

Question 42 says, a 5 year old boy is brought to the ED by his mom because of an episode of bloody stool 3 hours ago. Her mother says the stool was hard like bebbles and she noted bright red blood on the tissue when the patient cleaned himself. His previous bowel movement was 5 days ago. That's a long time. The patient has no abdominal rectal pain now, but he did have abdominal pain during his bowel movement 5 days ago. He has no histro of major medical illness and receives no medications. Vaccines are up to date, the patient has no recent histro of travel. He's at the 5th percentile for height and the 10th percentile for weight. BMI's at the 58th percentile. All signs are within normal limits. Abdominal examination shows hypoactive bowel sounds and a soft, slightly distended abdomen that is not tender to palpation. Rectal examination shows 1 centimeter of bright red retomicosa protruding from the right side of the anus. There's no retobleting. The remainder of the examination shows no abnormalities. Which of the fluen is the most likely cause of this patient's physical findings. Right. So we see this boy. He's 2 looks like pebbles. He's not pooped for a couple of days. He last pooped like 5 days ago. And then now he has this bloody stool. And his abdomen seems hard. You know, when you see something like this, this sounds an awful lot like constipation. This is a fairly common problem in kids. You don't poop enough. You're going to start having issues.

And then when you finally poop, because they are anal canal is very small. When that poop that has been stored up for a long time comes out, it kind of abrasives or you get like an abrasion of your rectal mucosa and that can cause bleeding. So I'm going to go definitely with option A here. This cannot be cystic fibrosis because we don't see any other thing here. We don't see any failure to pass meconium. We don't see recurrent respiratory problems. And when a child has cystic fibrosis, they're not going to be in a good percentile for weight. They're not going to be in a good percentile for BMI. This child is in a good weight and BMI percentile. We don't see any of those cystic fibrosis and tisidens. So we're going to skip that. Hirschprog's disease. Remember, you will also see like failure to pass meconium. These people may have like chronic constipation, they may have all those things. But many times they're going to have a prolonged history of it. This person, this is like the first episode. This is not going to be Hirschprog's disease. Again, look at the history. Don't just flagrantly ignore the history when you're reading these questions. And then who quorum infestation? Many times it's going to be a chronic problem. They'll have like chronic GI blood loss because of the worm. And many times they'll have like chronic abdominal pain and they will give you an tisidens like their eocenophils are elevated because it's a parasitic infection.

And you'll notice that they may have signs and symptoms of iron deficiency anemia. We don't see any of those things. It doesn't really feed the timeline given in this question. So that's wrong. And then option E says into susception. Into susception is a telescoping of the bowel. Many times they're going to have issues around the right lower quadrant. We don't see that in this patient. And don't get me wrong. It can cause like bloody stools. It can cause intermitth and abdominal pain. Right? But again, just number one, how spread out the symptoms are. It's like, wow, five days ago. Right? He had one bowel movement and then now he's having another bowel movement. I'm not going to go into a deception for that. And many times when you have into a deception, again, you're going to have pain localized to the right lower quadrant to the right lower quadrant. Right? And again, they will have like blood on the, you know, on their like bloody stools. Those red, corangelly stools. We don't really see that here. So I don't know if you're going to have a problem with that. Those red, corangelly stools. We don't really see that here. So I don't think I'm going to go with that for this person. Again, he has bloody stools, but he's just missing certain key elements of the history. Right? Missing certain key elements of the history, like the right lower quadrant pain because the telescope and usually happens around the terminal, Ilyam area.

Because remember, the terminal Ilyam has pyrospatches. It's a side of inflammation. Right? So those things can become anitis for that telescoping of the bowel. We don't see that here. We don't see that here. We don't see that here. Right? Those other alarm symptoms of interception. So I don't think I'm going to go with that for this one. Right? It's just the presentation here, the constipation, the pebble like stools and all those things. Those things are just more indicative, more indicative of constipation. All right. Now question 43 says, a 25 year old woman comes to the office because of a three day history of fever, chills, severe headache, weakness, muscle pain, loss of appetite, vomiting, diarrhea, and moderate abdominal pain. She's in nursing school and returned from a medical mission stripping West Africa 10 days ago. Exposure always tells you something, right? Her symptoms began abruptly while she was shopping in a supermarket after her return. At temperature is 102.2, pulse is 100, reservations are 22 per minute, and a blood pressure is 110 over 70. The patient appears ill and is in mild respiratory distress. Physical examination shows poor skin, turgor, and hyperactive bowel sounds. Most strength is 4 out of 5 throughout, lapsal tissue, lucopenia, and thrombocytopenia. Which of the following is the most sensitive and specific test for detection of the suspected viral genome in this patient? Right?

So this person, you see a person that is returning from West Africa. Right? We literally see a person that is returning from West Africa. Right? From West Africa has fever, has chills, has severe headache, has weakness, muscle pain, right? And these problems, right, has a lot of these problems, right? And you see that a symptoms kind of begun abruptly, a symptoms kind of begun abruptly, and her white count is pretty low, and her platelet count is also pretty low, right? Again, do not ignore the importance of exposures. Do not ignore the importance of exposures on your exams, right? Do not ignore the importance of exposures on your exams, right? So what do you think this person has? What do you think this person has? You see a person that just returned from West Africa. Well, one thing you may be thinking about is, ooh, could this be malaria? But again, if you notice, they are asking about a viral genome. So because they are asking about a viral genome, it's highly, highly, highly unlikely that it's malaria, because malaria is not a virus, right? Plus modium, false siperium is not a virus. And many times that's going to cause more of anemia instead of a leukopenia or a thrombocytopenia. That does not really fit what we have here, right? So what else should you be thinking about? What else should you be thinking about here? Well, one of the things you should think about here is something like Ebola, right? Although I know you may be like, divine, could this be dengue, right?

Dengue. The thing is, if people have dengue, they're going to have like bone breaking fever, very, very severe bone pain. That's going to be a prominent feature of these people's illness, right? You're going to see very, very, very, very severe bone pain, very, very severe bone pain, right? But the severe bone pain is not a feature that we see here, right? So this person, I'm going to say that this person very likely has Ebola, because Ebola has a very certain, like, very classic presentation that it follows, right? Very classic presentation that it follows, right? So usually it's going to start off as if you have the flu, right? You're going to have like a lot of fatigue, a lot of fever, a lot of, you know, weakness, right? You're going to have pain, your muscle hurts, your joints hurt, you're going to have sore throat, right? You're going to have sore throat. And you're going to have high fever. Usually it's going to be over 101 on your exams, right? Over 101 on your exams, right? So that's how it will start. But over time, you'll then start having a lot of vomiting, a lot of diarrhea, right? A lot of vomiting, a lot of diarrhea, right? So you may say that, wow, divine. I learned this as Ebola with hemorrhagic fever. No, it doesn't start off with the hemorrhagic fever. It starts off with flu-like symptoms. It starts off with flu-like symptoms. It's later in your disease course where things are going really bad. That then you're going to start having like DIC.

You're going to be coughing up blood. You're going to be, you know, stoolyne blood. You're going to be having like signs and symptoms of DIC. You're going to have PTKI prepare on the skin. You're going to have those things, right? They may bleed into their eyes, right? So that's not how things start. So just be careful about that. Because again, honestly, they put the hemorrhage, oh, the hemorrhage, the hemorrhage. This question will become easy. Everybody will crush their USME Ls. Obviously, that does not happen, right? So again, they are very good about kind of masking things. So just be careful. They don't start off with hemorrhage. They start off with sodium flu-like symptoms, very high fever over 101. And then they progress to hemorrhage. So how do we identify Ebola? Well, typically, you're going to identify with PCR. You're going to identify with PCR. So the answer has to be option C, right? But let's look at these other answers. Microarray analysis is kind of a bogus answer. I'm not going to consider that. Let's look at these other other plots. These other plots are kind of high you to know. So how does northern plot work? Remember, northern plot is to detect RNA. I just like to remember with the mnemonic not read it, not read it. You know, like a movie that is NR, not read it. Use northern plots to detect RNA. How exactly does that work?

Well, the way that works is that you're basically going to first, you know, separate the RNA strands using like gel electrophoresis, you know, like agarose gel. And then after you do that, because the thing is for all these plots, you want to know what you're testing for. You want to know the probe that you use, and you want to know the utility of the test. So what are your testing for the probe you use and the utility of the test? For northern plots, you're testing for RNA. You're testing for RNA, right? So you separate the RNA fragments with gel electrophoresis. And then after that, you're going to find a complementary DNA sample that combines to that RNA, to that is complementary to that RNA. So that's use a DNA probe. And then why do we check RNA? Well, what is RNA and indication of? RNA is an indication of genetic expression. Is an indication of what genetic expression and indication of what genetic expression. So you use this to find the level of gene expression. OK, how about southern plots? How about southern plots? Southern plots is something used to detect DNA, right? I remember it with the nomonic South Dakota, SD, South Dakota, or school district. We're using to detect DNA, right? So again, what are the processes in a southern plot? Well, number one, you're going to start off kind of digesting those DNA fragments. You're going to use like restriction enzymes, right? And then after that, you obviously, you have a mishmash of DNA fragments.

You want to separate those out. Well, how you're going to separate those out? You're going to separate those out again with gel electrophoresis. You can use like agarose gel. Agarose gel. And then now that you've separated the DNA fragment, your job is, hey, I want to identify a specific DNA sequence. Well, the good thing is that DNA can bind DNA. So what you can do is you can find a complementary DNA sequence, a DNA probe. So use a DNA probe for this, just like you use a DNA probe for northern plot. And then basically, that DNA probe that is complementary, you can use it to identify specific sequences. So what is the utility of the southern plot? You use the southern plot to identify specific parts of the genome, right? So if you're looking for polymorphism, you can use the southern plot for that. If you're looking for a specific gene deletion, you can use the southern plot for that. Basically, if you want to identify something that is more of the DNA level, you can use the southern plots to make that happen. OK, how about the western plot? The western plot is used to identify protein. I like to remember it with the numonic Washington Post. You're like, man, you really use numonics. But you're using it a ton today. The thing is with some of these things, I don't know for whatever reason, some of these topics between our 41 to 50. One thing that seems to help a lot is numonics, right? It's just where I remember some of these things.

So Washington Post is a very popular newspaper in the US. And by the way, I don't know if I'll get to 50, because I don't want to rush my way through these things. And I want to keep these podcasts, these free 120 podcasts as like little sections you can listen to. So again, we'll see, I will try to get up to 50, but I may not, I may not, I may not. All right, I may do like a part B for this particular section. So the western plot is used to identify protein. It's used to literally identify protein. You literally used to identify protein, right? So how does that work? Well, since you're trying to identify protein, I don't know if you're going to be using any kind of like DNA probe or anything here, that doesn't really make any sense. Right? So we're going to use, we're going to identify proteins. If you're trying to identify a protein of interest, well, we know that typically proteins can be bound by antibodies, right? Antibodies love to bind proteins. Most antigens are going to be protein-based antigens. So you're going to find an antibody that is complementary to that protein and can bind it, right? And you may wonder like, define like, why is it? Why? And remember, western plots, right? You can use it to detect many things, right? You can use western plots to detect many things, right? So like, for example, the asserting bugs you can identify with western plots, right? You can do things like recognizing, I believe, Borrelia Bokdoferi, that causes Lyme disease.

You can use a western plot to identify B-bokdoferi, right? So you may wonder like, after these probes are attached to these things, how do we know that we found these things? The thing is, many times you use some kind of like florescence or something of that nature, some kind of reaction when binding happens to tell you that, ooh, this probe I used has detected this thing that I'm dealing with. So please make sure you know your plots for your exams. So northern plot for RNA, southern plot for DNA, western plot for protein, right? So remember, North rated South Dakota and Washington Post. If you remember those, you're gonna be in good shape for your exams. Now remember, we use PCR a lot these days, right? Like to identify gonorrhea infection, chlamydia infection, even HIV, we do a lot of PCR these days, all right? Cause PCR is pretty quick to do, right? It's pretty quick to do. All right, and I would encourage you to try to see if you can learn the steps of PCR. That's a very classic thing they love to test on the USME Ls, the steps of PCR, I'll let you kind of study that in your own time. All right, now question 44 says, a 56 year old man comes to the office, because of a one month history of pain and tingling of his hands and a six month history of parasteges of his feet, okay? As part of the workup, okay? A nerve biopsy specimen is obtained and analyzed at the electron microscopy level.

All right, the biopsy specimen shows Mark loss of structures labeled by the excess in the photomicrograph of a normal biopsy specimen. The loss of these structures is most likely to cause which of the following neurologic findings in this patient, right? So again, before you start looking at these things, work it out and I know some people are kind of like scared. They're like, oh, oh, I have never seen this before. And that's fine. If anybody tells you that, oh, after they teach you, everything you're gonna see on your exam, you have no issues with it. That person is a big fat liar. That person is literally a big fat liar, right? So you're gonna see things that you've never seen before. But again, there are many principles, techniques, and strategies you can use to kind of work your way around these things, right? Again, I will encourage you if you're a person that really struggles with testing principles and approaches. I was strongly encouraged to consider my test taking strategies class. I actually have a class coming up next month. It's coming up about three and a half weeks from now. I think you'd find it to be tremendously helpful in your prep for your USMLE exams. All right. So this person, let's work it out first. Let's see, can we answer this question without even looking at the image? That's a nice goal to have because I tell people this, about 80% of the questions you're gonna see on your USMLE exams that have images and audio.

You typically do not need the images or the audio to arrive at the right answers. If you read your question carefully, if you read your question right, you're usually gonna be in pretty good shape on your exams, right? So let's ask ourselves, what does this person have? Well, half, this person probably has diabetes, right? This person probably has diabetes. I think that's a very, very reasonable assumption to make here. This person probably has diabetes, right? And remember, when people have diabetes, they tend to have like a pins and needle sensation, right? They tend to have like altered sensation of like pain or temperature. That's why if they like step on needles, they may not realize it, they may have a wound in their leg, they may not know. Because think about another person like me and you. If you step on a needle or a nail or you have a wound in your leg, it's gonna hurt. You're gonna feel it, you're gonna be like, oh, it hurts, it hurts. But people that have diabetes, they don't sense it. That's why they tend to have all these wounds. They may have these polyhylene ulcers and all these things, right? So that's what you know, right? Because the thing is, many people think the USML is, the stocking trade is to test things that have never been seen before. No, that's not what they do. They test common things, they just find unusual ways to test them.

And many times those unusual ways depend on you, not number one, not overthinking, and number two, understanding pathophysiology, right? So we know that people that have diabetes, you know, we know they have pins and needles issues, we know they have all these problems. So let's just look at the answer choices and ask ourselves, which one matches the best with just classic things we know about diabetes? Well, the thing is, decrease sensitivity of the deep tendon reflexes. Okay, don't get me wrong. Yeah, diabetes can mess up your reflexes, right? Diabetic neuropathy, right? Neuropathy. So we know that this answer has to relate to neuropathy in some way shape or form. So let's keep that answer. Option B says, impaired stereognosis. I don't think I'm gonna pick this one because if you have impaired stereognosis, what is stereognosis? It's like your ability to identify 3 D shapes. Say, for example, your eyes are closed and you touch a solid object, recognizing the structure of that object, right? That is not something that is usually impaired in a person that has diabetes. So I'm gonna say that that's wrong. Option C says loss of pain and temperature sensation. That sounds a lot like what I described as the classic problems that we have in diabetics. So we're definitely keeping that one. So we're keeping A and C for now, and I'm definitely leaning more towards C than I'm leaning towards A, right? And then option D says muscle atrophy. I'm not going to pick that, right?

Diabetes, don't get me wrong. Can the neuropathy cause muscle atrophy? It absolutely can. But again, is muscle atrophy a classic presentation of diabetes? No. We tend to see that more with myopathies or pressing having like low motor neuron symptoms. Let's say you have like a problem at like in your ventral horn of the spinal cord, right? Like West Nile virus or polio anything like that. I'm gonna cross out option D. And then option E says viso constriction again. This question is focusing so much on neuropathy. It's not focused so much on viso constriction. So I don't know if that really makes any sense to pick that answer. So we're between options and C. So we ask ourselves which one is more classic for diabetes? Option C is more classic. So I'm gonna go with option C here. I really love this question because it's one of these things where it's like, wow, this image is not something that, and if you actually look up this electro-micrograph image, those are actually a pain and temperature fibers. But the thing is, even if you did not know that, and to be honest with you, let's be realistic, because honestly, like trying to come here and sound really smart and say, oh, you must recognize this fiber. Blah, blah, blah, blah, blah. That is just not realistic, right? That is just not realistic. It's not, that's the truth. That is literally not realistic. It's literally not realistic.

The realistic thing is to be honest with ourselves that, hey, there's gonna be questions like this where it's like, I have no idea what's going on. But you can still wriggle your way to the right answer. And I've tried to show you an approach with this question as to how you can wriggle your way to write answers on the exam when you have limited information. Use what you have to get what you want. All right, let's do question 45. That's probably gonna be the last question we do. And then I will kind of pick up from 46 in the next podcast, right? But we have a five month old boy who's brought to the clinic by his mother because of a 10-day history. Again, I don't wanna hurry. I'm trying to hit some of these testing principles and stuff. So I'm not trying to hurry through this. So five month old boy is brought to the clinic by his mom because of a 10-day history of coughing spells that occur several times daily and last one to two minutes. He often vomits afterwards. This is pretty classic. Your cough, I like to call this cough plus the soda. Your cough is so bad that after your cough, you vomit after your cough. Or after your cough, you pass out. You have syncopy or precincopy after your cough. Or your cough so hard, and after your cough, you blow the blood vessels in your eye, right? You have subconjunctival hemorrhage. That's pretty classic for something. Well, let's finish this. It was delivered at a term to a 16 year old patient who was having a 1-par-1.

Following an uncomplicated pregnancy and spontaneous vaginal delivery in Mexico. Okay, he's parents integrated to the US shortly after his birth. He has no history of major medical illness and receives no medications. He has never been to a physician for a well-child exam. Surprise, surprise. And has not got any vaccines, surprise, surprise. So knowing that this person was delivered outside of the US and has not got any vaccines, that should tell you all you need to know. You should be able to answer this question. But again, I always tell people do not jump the gun. Do not commit the error of premature closure with questions. Finish the whole queue stem first, right? He appears well. Vital signs including oxygen saturation or within normal limits. During the physical exam, he coughs uncontrollably for two minutes after which there is a gasp in sound. I wonder why and subsequent vomiting. Afterwards, he appears exhausted. Physical examination shows no nasal flaring or intercostal or subcostal retractions. The lungs are clear, noises or crackles are heard. A drug from which of the following classes is most appropriate for this patient. This person clearly has pertosis, clearly, clearly has pertosis, has whooping cough. And remember, how do we treat pertosis? You're gonna treat it with a microlete. You're gonna treat not just the patient, but you're also gonna treat their close contacts. Even if their close contacts have been vaccinated, it does not matter.

You're gonna treat the patient and their close contacts. So this is pertosis, it's gonna be controlled with a microlete. So the answer is gonna be option C. Remember, pertosis is a bacterial infection that you could have prevented if you got your vaccines. But one other thing to know about pertosis is that it produces a toxin that causes lymphocytes to proliferate. So sometimes you can see profound lymphocytosis in a person that has pertosis infection. Don't let that sway you on start thinking of some leukemia or lymphoma or anything like that. Leukemia is lymphomas, you're not cause this kind of crazy, crazy, crazy cough. All right, so microletes are gonna be exactly what you're gonna be doing on your exam, right? Not a cephalosporrine, not a fluoroquinolone. Remember, fluoroquinolones prolong your acute interval and the ruptured achilles tendon, right? Not penicillin, not so photomide. Remember, you saw phonomides in the context of like trimethyramsophamethoxys or tomanich like PCP pneumonia or in the context of pyramidamin and sulfodiasin to manage toxoplasma, gondii. All right, so I think we should stop here. I think this is a good stopping point. Again, if you're interested in any of my classes, my test taking class, my bio-stats class, my social sciences and ethics class, I have classes in the month of April. Shoot me an email, I can give you some more information. Those are first step one, two, three. And then I have a 20 hour step two, step three class.

I have a last minute review. Those are first step two, step three. And then I have this once in a year class, very amazing class, 50 hour class, first two weeks of the month of June. It's first step two and step three. Oh my goodness, if you attend that class, it's gonna help you tremendously on your exams. I've had many people take that class and they've done superlatively well on their USME Ls. Limited registration for that, there's not enough spots available. So if you're interested, shoot me an email, I can give you some more information. And then I also offer one on one to you during for all the USME Ls and complex exams and I help with eras applications, personal statements, reclators and all those things. And then I have these podcasts on Apple Google Spotify. So check those out. And then I also have a website, you know, have a website where you can see all my podcasts for any episode, one all the way to 5.85 I guess, right? And then I also have a You Tube channel, you can check out Divine Intervention, USME Ls, Podcasts and videos. That's where I post the videos that I make. And then finally, I have another website called Divine Intervention Lifelessens.com. Divine Intervention Lifelessens.com. Every week I post like two or three podcasts from a biblical perspective address a life lesson. You know, many of you don't have a question. So Divine Intervention Lifelessens.com, I put these life lessons on there. Many people listen to those.

There's actually more than like 310 episodes. And people find it to be very helpful. There's an Apple Podcast associated with that called the Divine Intervention Lifelessens Podcast. So thank you for listening to me today. I will see you in episode 586. I'm gonna complete questions for the 6 to 50. And then I'll, I think I'll go on to my 10 per podcast studying from 51. Again, you may notice that some of these ones, I mean, spend like more time on certain questions because they are principles I wanna teach and they are things I wanna go over. You know, like for example, I found it very useful, I think here to kind of go through these different plots because it's something that's very high yield. It's not something just wanna blow through. I don't wanna say, not them plots, this. Why some plot, that? No, it's not useful for you at that point, right? So I wanna make sure that you truly understand what's going on here. All right, so thank you for listening to me today. I'll see you next time. God bless you and bye for now. Thank you.

RNA (Ribonucleic Acid).

To detect and quantify specific levels of RNA transcripts (e.g., mRNA) within a sample, allowing for gene expression analysis.

Southern blotting detects DNA; Northern blotting detects RNA.

A labeled probe that is complementary to the target RNA sequence.

It suggests alternative splicing or the presence of multiple isoforms of the transcript.

Relative differences in gene expression levels (transcription rates).

Northern blotting.

Specific RNA molecules (e.g., mRNA, rRNA).

To hybridize specifically to and bind with the target RNA sequence.

Relative differences in gene expression levels.

Southern blotting.

Different sizes (nucleotide lengths) for the same gene product.

Northern blotting.

Specific RNA molecules (e.g., mRNA, rRNA).

To hybridize specifically to and bind with the target RNA sequence.

Relative differences in gene expression levels.

Southern blotting.

Different sizes (nucleotide lengths) for the same gene product.