The Student Room Group

Describe the structure and function of DNA or RNA

Im really stuck on this topic and its stressing me out. A simplified version would be really helpful as well as anything. I meant to write dna and rna not or.
(edited 6 years ago)
Just curious, what do you need this for? Because I'm doing my transition work and I'm stuck too
Reply 2
Hi

I have finished A level biology
Do you need a basic structure of both or a comparison of the two?
Reply 3
Original post by CuriousCat567
Just curious, what do you need this for? Because I'm doing my transition work and I'm stuck too

Im doing that too
Reply 4
Original post by elz71
Hi

I have finished A level biology
Do you need a basic structure of both or a comparison of the two?


A basic structure of both please
Original post by Ameerahs
Im doing that too


Is it a pixl edge booklet by any chance?
Reply 6
Original post by CuriousCat567
Is it a pixl edge booklet by any chance?


Yep, my school decided to give it out on results day 🙄
Original post by Ameerahs
Yep, my school decided to give it out on results day 🙄


I literally just made my mind up about my a-levels like 3 days ago so my school's not gonna be happy when I go back and say I want to change all my subjects xD Do you think we could help each other get through the booklet as I'm struggling too? Quick question, how did you manage to do the reasearch activities as 1 page of cornell notes?
Reply 8
Original post by Ameerahs
A basic structure of both please


Hopefully this is right, it was first year stuff so double check if you can

DNA =
-It is formed of monomers called nucleotides
-These nucleotides are formed of three parts - a five carbon sugar (pentose sugar), a phosphate group and a nitrogenous base
-in DNA the five carbon sugar is called deoxyribose
-the nitrogenous base can be one of four types in DNA these are; adenine, guanine, cytosine and thymine
-each nucleotide is joined together by a covalent bond
-the covalent bond is between the phosphate group of one nucleotide and the third carbon atom of the pentose sugar in the next
-when many nucleotides are joined together this forms a sugar phosphate backbone (a nucleotide chain)
-DNA is formed of two nucleotide chains
-these nucleotide chains are joined together by hydrogen bonds between the corresponding nitrogenous bases (A=T and C=G)
-this forms a ladder like structure
-due to the nature of these bonds the DNA forms a helix (twisted structure)
-that is why DNA is referred to as having a double helix structure

RNA =
-RNA has the same basic structure to DNA
-it is also formed of nucleotides which follow the same structure the nucleotides are also joined together by covalent bonds in the same way that DNA is
-There is however one key difference - the pentose sugar is ribose
-Also it does differ when it comes to the nitrogenous bases. Thymine is replaced with uracil. So the nitrogenous bases in RNA are adenine, guanine, uracil and cytosine
-RNA is also single stranded as its role is in protein synthesis (you may learn about other roles during your A level depending on your course)
-RNA is single stranded as it must leave the nucleus to enter the cytoplasm during protein synthesis (as DNA is too large to leave it)
-RNA also follows the same base pairing rules as DNA. The nitrogenous bases are hydrogen bonded together with the same base pairs (A-T, G-C)

Basically DNA and RNA are pretty much the same Other than the key three differences (RNA is single stranded, RNA has a ribose sugar instead of deoxyribose and RNA nucleotides have a uracil base rather than thymine)
Their phosphates, sugars and bases show the same bonding patterns to form nucleotides and their nucleotides bind to form nucleic acids in the same way

Let me know if that's any help at all or you have any other questions! :smile:
Original post by CuriousCat567
I literally just made my mind up about my a-levels like 3 days ago so my school's not gonna be happy when I go back and say I want to change all my subjects xD Do you think we could help each other get through the booklet as I'm struggling too? Quick question, how did you manage to do the reasearch activities as 1 page of cornell notes?


I believe we have the same booklet! The links given in it had pages and pages to read, I had no idea how to effectively condense it down, I just ended up writing no where near as much as I hoped! 🙄
Reply 10
Original post by CuriousCat567
I literally just made my mind up about my a-levels like 3 days ago so my school's not gonna be happy when I go back and say I want to change all my subjects xD Do you think we could help each other get through the booklet as I'm struggling too? Quick question, how did you manage to do the reasearch activities as 1 page of cornell notes?


Yeah we could help each other but i haven't started the cornell notes yet for that exact reason.
Reply 11
Original post by elz71
Hopefully this is right, it was first year stuff so double check if you can

DNA =
-It is formed of monomers called nucleotides
-These nucleotides are formed of three parts - a five carbon sugar (pentose sugar), a phosphate group and a nitrogenous base
-in DNA the five carbon sugar is called deoxyribose
-the nitrogenous base can be one of four types in DNA these are; adenine, guanine, cytosine and thymine
-each nucleotide is joined together by a covalent bond
-the covalent bond is between the phosphate group of one nucleotide and the third carbon atom of the pentose sugar in the next
-when many nucleotides are joined together this forms a sugar phosphate backbone (a nucleotide chain)
-DNA is formed of two nucleotide chains
-these nucleotide chains are joined together by hydrogen bonds between the corresponding nitrogenous bases (A=T and C=G)
-this forms a ladder like structure
-due to the nature of these bonds the DNA forms a helix (twisted structure)
-that is why DNA is referred to as having a double helix structure

RNA =
-RNA has the same basic structure to DNA
-it is also formed of nucleotides which follow the same structure the nucleotides are also joined together by covalent bonds in the same way that DNA is
-There is however one key difference - the pentose sugar is ribose
-Also it does differ when it comes to the nitrogenous bases. Thymine is replaced with uracil. So the nitrogenous bases in RNA are adenine, guanine, uracil and cytosine
-RNA is also single stranded as its role is in protein synthesis (you may learn about other roles during your A level depending on your course)
-RNA is single stranded as it must leave the nucleus to enter the cytoplasm during protein synthesis (as DNA is too large to leave it)
-RNA also follows the same base pairing rules as DNA. The nitrogenous bases are hydrogen bonded together with the same base pairs (A-T, G-C)

Basically DNA and RNA are pretty much the same Other than the key three differences (RNA is single stranded, RNA has a ribose sugar instead of deoxyribose and RNA nucleotides have a uracil base rather than thymine)
Their phosphates, sugars and bases show the same bonding patterns to form nucleotides and their nucleotides bind to form nucleic acids in the same way

Let me know if that's any help at all or you have any other questions! :smile:

Thank you! I will do. Just one more question. What do DNA and RNA do?
Reply 12
In basic terms DNA contains the complete genetic code of an organism whereas RNA contains a small amount of transcripted DNA that is used for a specific function for instance making proteins. In protein synthesis the area of bases required to code for a protein is 'unzipped' (the hydrogen bonds between the nitrogenous bases are broken down) by the enzyme helicase and RNA is transcribed from this unzipped part of the DNA. Free nucleotide bases line up to their complementary base on the DNA and then joined together to form a nucleotide chain called RNA. So RNA is a smaller portion of genetic code that can leave the nucleus ready for translation into a polypeptide chain (protein)Don't worry if you don't understand this at the moment, I didn't know any of this at the start of year 12 you'll probably cover it in tons of detail ( or at least by the end of year 13 it will have been drummed into your head)

If I were you I would get the CGP biology revision guide to eventually use alongside your textbook as it breaks down the knowledge into easier to grasp chunks - I found that really helpful!
(edited 6 years ago)

Quick Reply

Latest