MCAT-DNA/RNA stuff

[drguy22]

ok..i saw the thread on magnitism so i though we should do this for as many topics as possible.....this is all i know about DNA/RNA

DNA

Base pairs: Adenine, Thymine, Guanine, and Cytosine (ATGC)
-A pairs with T and have 2 possible hydrogen bonds.
-G pairs with C and have 3 hydrogen bonds and is therefore stronger.
-The strength of the DNA molecule is determined by the number of GC base pairs there are.
- DNA repilcation is semi-conservative, which means that for every new DNA strand that is replicated, there is always one parent strand.
- DNA replication is semi-discontinous which means that there is a leading strand and a lagging strand.
- Replication starts in the replication fork, where the helicase binds and "unzips" the double stranded DNA. You need a RNA primer to get started with the replication. DNA is synthesized 5' to 3'.
- the lagging strand is synthesized in bits called okazoki fragments and are annealed together with an enzyme called ligase.

RNA

-Base pairs: A U G C (there is no T)
- RNA is usually single stranded
- there are 3 types of RNA
-messenger RNA aka mRNA- this contains the "message" or code for the protien to be
-transfer RNA aka tRNA- this carries the amino acid and puts it in the right spot.
-ribosomal RNA aka rRNA- the main component of ribosimes.


DNA to RNA= trancription


i hope we can continue this....we can go all the way to protien synthesis and structure and all tat goos stuff.....if i left anything out or am wrong just add on to the list 🙂

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[Shades McCool]

There are more than three types of RNA hoss.

 

[bella_dottoressa]

True, but I don't think much is going to come up on the other kinds unless it's in a passage...except maybe snRNA is in snRPs, which along with protein makes up the spliceosome that cuts up the mRNA i do believe.

I'll also add little trivial facts off the top of my head that I've seen come up in stand alones along the same RNA lines...

rRNA is the most abundant type of RNA, tRNA is the physically smallest and has a clover leaf shape.

 

[amy73]

Hi,
I have heard that genetics is now a favoutie on the MCAT.. but i dont see much of that on 3r or 4r .. just a few standalones.. how many passages can one expect to see on that stuff now? Does 6r or 7r have more of it..?

This is how i keep genetics straight..
replication.... transcription... translation.

Anytime i see a replication fork.. i think dna replication.. leading lagging and okazaki fragments.. someone needs to start. think rna primer. Someone needs to unwind it think toposiomerase.. someone needs to unwind helix ..think helicase. Once replication is done. stich the pieces together by ligase.. and then proofread by DNA pol 1.

Anytime u see a small piece of thread hanging by the dna. think mrna transcription.. remember the dna will not come out of nucleus to be copied(!!) . so transcrition will have to be nuclear. so mrna made in nucleus.. Now that nucleus has to finish the important message so mrna is dressed up with capping and splicing and the ployA tail...and ready..

Now action moves out. . via the pores and the ribosomes find the little friendly leaf which is trna and bring the major players together.. which means the ribosomes.. now the actual talking/translation occurs via p site and a site. Again make sure u get the amino and carboxyl end thing correct and then once all talks are finished then the stop codon comes in and E site or Exit site comes into play.. As proteins are being made the ER starts off by attaching the SRP to it and tries to get it inside the lumen where the protein is glycosolated/not depending on its role/function in cell.

This is a pretty loose description.. but it works for me..
Bye
Amy
+

 

[Psycho Doctor]

no it sounds good...works for me, but when i jump topics like that (from my own studying) my brain hurts...

 

[ExplodingBoy]

a quick thing to separate transcription from translation (because i know i always would get them confused when in a hurry), translation is going from one language to another, in this case its the RNA language to the protein language.

thats about all the help I can offer on DNA/RNA. I hate genetics....

 

[drguy22]

hahaha...i got confused with transcription and translation on my biochem exam...an easy question🙁 BUT i got a 91/100 anyway 🙂

 

[Shades McCool]

How can you get the two mixed up...they are so different!

 

[ExplodingBoy]

the words are similar, thats what snagged me. the processes i understand are different, it's just remembering which is called what

 

[Shades McCool]

I guess being a Molecular Biology major has its advantages.

 

[dandelion]

And don't forget the structure of nucleotides & how DNA/RNA is put together (sugar-phosphate backbone, the bases are connected to the sugar).

[Had the (mis)fortune of finding this place 10 days before the MCAT.]
--dandelion

 

[DieselPetrolGrl]

And don't forget the structure of nucleotides & how DNA/RNA is put together (sugar-phosphate backbone, the bases are connected to the sugar).

[Had the (mis)fortune of finding this place 10 days before the MCAT.]
--dandelion

would you mind adressing the types of bonds that hold the backbone together? i dont know what they are and my kaplan book doesnt mention them.
(all i know is the hydrogen bonds between the nucleotides)

also 5' Phosphate end & 3' hydroxyl end

 

[RayhanS1282]

phosphodiester bonds