<p>Without giving too much of the &quot;what they want you to do yourself&quot; bits of this away, here are a few explanations of the image that may help you answer this question:</p>
<ul>
<li>As mentioned in the text, the forward and reverse primers are underlined in the image.</li>
<li>The <code>-</code> and <code>+</code> symbols below the forward-direction sequence help determine the positions of the bases above and below. A <code>+</code> appears every 10 bases.</li>
<li>The first base in the sequence is at position 1441 (as indicated by the numbers) to the left of the sequence. The first <code>+</code> to the right of that first base represents position 1450.</li>
<li>Primers are usually represented as a sequence in a &quot;5-prime to 3-prime direction&quot;, which is almost always the left to right direction of the top sequence in an image like this, and the right to left direction of the bottom sequence.</li>
<li>The length of a PCR product includes the primer sequence.</li>
</ul>
<p>For help beyond that explanation... this looks like a canned question. Unless you give more context around what bioinformatics project you're working on and how this question relates to your project (i.e. explain why it's a real-world problem rather than a text-book question), I'm going to leave answers to the specific questions asked as an exercise to the reader.</p>

CC BY-SA 4.0
2023-10-17T06:19:58.927Z
So in this case what would be the length?
Teo
CC BY-SA 4.0
2023-10-17T10:06:12.197Z
I'm happy to help you understand the question, but I don't want to help you answer this question beyond that understanding. Other people are welcome to do that if they desire.
gringer
CC BY-SA 4.0
2023-10-17T11:07:51.130Z
Thank you for that! But as the questions says, I need to determine the size of the PCR product. Is there a formula for that?
Teo
CC BY-SA 4.0
2023-10-17T12:01:05.757Z
@Teo you should be able to figure out the formula from what gringer has told you. We are not a homework writing service, our job is to help you understand so _you_ can figure it out. So please read through what gringer has written, and see if you can figure it out. Then, if you still need help, update your question and add what you think the solution is and how you found it and then we can help you take it from there. If the information given here isn't enough for you, then update your question and add what you understand and what you feel is missing.
terdon
CC BY-SA 4.0
2023-10-17T15:49:57.360Z
something about 1.5MDa in weight ?
pippo1980
CC BY-SA 4.0
2023-10-17T18:32:05.823Z
@Teo Indeed there is a formula: `b - a`, where a is the start and b is the end point :)
Cloudberry
CC BY-SA 4.0
2023-10-18T18:17:01.897Z
@Teo if I start reading a book on page 20, and then close the book after page 30 and go have a cup of coffee, how many pages have I read?
Maximilian Press
CC BY-SA 4.0
2023-10-17T03:12:43.423Z
2023-10-17T20:04:54.163Z
2023-10-17T20:04:54.163Z
gringer
<p>I would like to know the steps of this question and how to determine the forward and the reverse primers and also the length of the sequence, without using NCBI. If you could explain and give an answer step by step I would appreciate it. Thank you<img src="https://i.sstatic.net/t2Goz.png" alt="the sequence is in the attached image" /></p>

CC BY-SA 4.0
2023-10-17T08:24:12.093Z
Wouldnt it be a question for chemistry or biology stack ?
pippo1980
CC BY-SA 4.0
2023-10-17T13:38:14.760Z
You are the second person to have raised this @pippo1980 exact point, Biology SE was suggested. If you flag this formally it helps to decide about migration.
M__
CC BY-SA 4.0
2023-10-18T18:10:31.503Z
I think it should be on SE Biology. Trying to flag with this.
Maximilian Press
CC BY-SA 4.0
2023-10-19T02:07:30.673Z
This question tells me that you do not understand how PCR works. You should figure it out. Use Google search.
Supertech
CC BY-SA 4.0
2023-10-24T14:20:07.463Z
Just to note, the question has now received 2 closed requests.
M__
<homework><sequence><primer><pcr><dna>
1.What size PCR product will be generated using the primers (bold and underlined) in the sequence below?
# 1.What size PCR product will be generated using the primers (bold and underlined) in the sequence below?

(Asked by: username_0 on 2023-10-16)

I would like to know the steps of this question and how to determine the forward and the reverse primers and also the length of the sequence, without using NCBI. If you could explain and give an answer step by step I would appreciate it. Thank you![the sequence is in the attached image](https://i.sstatic.net/t2Goz.png)

**Tags:** homework, sequence, primer, pcr, dna
> **Comments:**
> **username_1**: Wouldnt it be a question for chemistry or biology stack ?  
> **username_2**: You are the second person to have raised this @pippo1980 exact point, Biology SE was suggested. If you flag this formally it helps to decide about migration.  
> **username_3**: I think it should be on SE Biology. Trying to flag with this.  
> **username_4**: This question tells me that you do not understand how PCR works. You should figure it out. Use Google search.  
> **username_2**: Just to note, the question has now received 2 closed requests.  

---

## 1 answers

### Answer by username_5 on 2023-10-17. Score: 3

Without giving too much of the "what they want you to do yourself" bits of this away, here are a few explanations of the image that may help you answer this question:

* As mentioned in the text, the forward and reverse primers are underlined in the image.
* The `-` and `+` symbols below the forward-direction sequence help determine the positions of the bases above and below. A `+` appears every 10 bases.
* The first base in the sequence is at position 1441 (as indicated by the numbers) to the left of the sequence. The first `+` to the right of that first base represents position 1450.
* Primers are usually represented as a sequence in a "5-prime to 3-prime direction", which is almost always the left to right direction of the top sequence in an image like this, and the right to left direction of the bottom sequence.
* The length of a PCR product includes the primer sequence.

For help beyond that explanation... this looks like a canned question. Unless you give more context around what bioinformatics project you're working on and how this question relates to your project (i.e. explain why it's a real-world problem rather than a text-book question), I'm going to leave answers to the specific questions asked as an exercise to the reader.

> **Comments:**
> **username_0**: So in this case what would be the length?  
> **username_5**: I'm happy to help you understand the question, but I don't want to help you answer this question beyond that understanding. Other people are welcome to do that if they desire.  
> **username_0**: Thank you for that! But as the questions says, I need to determine the size of the PCR product. Is there a formula for that?  
> **username_6**: @Teo you should be able to figure out the formula from what gringer has told you. We are not a homework writing service, our job is to help you understand so _you_ can figure it out. So please read through what gringer has written, and see if you can figure it out. Then, if you still need help, update your question and add what you think the solution is and how you found it and then we can help you take it from there. If the information given here isn't enough for you, then update your question and add what you understand and what you feel is missing.  
> **username_1**: something about 1.5MDa in weight ?  
> **username_7**: @Teo Indeed there is a formula: `b - a`, where a is the start and b is the end point :)  
> **username_3**: @Teo if I start reading a book on page 20, and then close the book after page 30 and go have a cup of coffee, how many pages have I read?  

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