Question

!!! One Medal Question !!!

Answer 1

- How may mRNA be modified before it leaves the nucleus?

- Outline the steps of translation.

- Define mutation and mutagen.

Answer 2

@Zale101

Answer 3

I am guessing you are talking about mRNA ..... because there are tRNA, rRNA, snoRNA, snRNA etc etc that gets modified too

mRNA processing involves
5'capping
Addition of a poly A tail
Splicing (removal of introns and joining of exons)

The mRNA needs to be processed to
protect from degradation (5'cap and polyadenylation)
splicing - Remove intronic sequences which should not be coded and the exons joined
Attachment of various proteins to the mRNA to specify certain signals such as .... hnRNP binds only to intronic sequences , so if there are hnRNP still bound, thats a message to say that proper splicing has not occured and this will be a signal for the cell to degrade this mRNA sequence. Also there are proteins that binds to exons to specify that they are correct exons and also proteins that aids in exporting the mRNA from the nucleus to the cytoplasm and then once in the cytoplasm a new set of proteins will be bound to signal that the mRNA is ready for translation.
All these needs to happen ... if there is a mistake in any sequence ... the mRNA degradation mechanisms will take into effect (sensing its a bad mRNA) and will degrade it.

Answer 4

http://dwb4.unl.edu/Chem/CHEM869N/CHEM869NLinks/www.mun.ca/biochem/courses/3107/Lectures/Topics/RNA_Modifications.html

@Jigglypuff123 is correct

Answer 5

@Zale101 you too

Answer 6

so how is mRNA modified before it leaves the nucleus?

Answer 7

@Zale101 @Jigglypuff123

Answer 8

@AnImEfReaK

Answer 9

Well, mRNA is changes due to DNA. DNA has codes in the form of base pairs in a particular sequence, due to particular types of proteins needed by the cell. Because of this transcription occurs. The mRNA anticodes from DNA, that is is made to contain codes which are complimentary to the DNA by attaching to it. Then it leaves the nucleus. Do you understand it now?

Answer 10

Perfect !

Answer 11

For translation, the mRNA is left to leave the nucleus through nuclear pores, to be suspended in the cytoplasm. It then makes its way to a ribosome- you know where proteins will be made (amino acids will be assembled). The mRNA binds to the ribosome. Then tRNA arrives- it has complementary codes to mRNA so the same as DNA except the base T is U. The tRNA carries amino acids in that order, and they are joined by chemical bonds into a polypeptide chain- a protein.

Answer 12

this is for the second question ?

Answer 13

A mutation is a change in DNA- due to environmental factors, or inheritory. The change may be positive or negative depending on what it is. It changes the make up of the DNA. A mutagen is what causes a mutation- any factor increasing the chance of it to occur.

Answer 14

Yes all my messages are for each question. I hope my explanation gives you an understanding of genetics ^^

Answer 15

Thanks @AnImEfReaK 3 for 3 Great, all makes sense !!!

Answer 16

No problem :)