DNA vs. RNA and Transcription

DNA and RNA are the basis for all living things. There are some important similarities and differences between the two and their jobs.


DNA is the code for the actual genetic information, located in the nucleus, for every living thing. It contains the information that determines inherited characteristics. RNA is the polymer that is present in all living cells and is involved in protein synthesis. It copies the DNA for transcription, translation, and other processes.

DNA RNA
Deoxyribose for the sugar
Ribose for the sugar
Found strictly in nucleus
Found in nucleus and cytoplasm
Bases A (adenine), T (thymine), C (cytosine), and G (guanine)
Bases A (adenine), U (uracil), C (cytosine), and G (guanine)
Bases A – T math together, while G – C match together
Bases A – U match together, while G – C match together
Contains the actual genetic instructions
Copies the instructions in DNA to create new DNA and make proteins
Phosphate group
Phosphate group
Double helix
Three types: Messenger RNA, Transfer RNA, and Ribosomal RNA
external image dna_versus_rna_reversed.jpg

Above is a picture of both a strand of DNA on the left and a strand of RNA on the right. As shown, the DNA is a double helix, while RNA is a single strand. The bases for DNA are C, G, A, and T and for RNA they are C, G, A and U (instead of T). Each has a sugar phosphate backbone.

external image dna-structure.jpg


Above is a picture of a strand of DNA. Where as RNA is one stranded, DNA has two strands. As shown, each colored band is a base. The A bonds with T and the C bonds with G. When RNA moves in for transcription, A bonds with U and G bonds with C.

Transcription


Transcription is the copying of a DNA strand by a messanger RNA strand so that the RNA can return to the cytoplasm to create a protein (using the DNA for the code). mRNA moves into the nucleus, and the DNA begins to split in half. As it does, the mRNA moves between it, matching up the bases. This process is shown below

external image c7.17.7b.transcription.jpg
RNA nucleotides fill in to copy the DNA as it moves through. Once the RNA is done with it, it joins back with it's counterpart strand.

http://www.youtube.com/watch?v=vJSmZ3DsntU
The video describes the process of transcription. The double helix of DNA unwinds and splits up, allowing the messanger RNA to come in between it and match up with it's counterparts. Once the process of matching up is complete, the mRNA moves out of the nucleus and into the cytoplasm to travel to a ribosome, where the next step of completeing DNA replication will occur.

When transcription occurs, the RNA U base goes with the DNA A base, and the usual G goes with C.
There can be errors during transcription. The wrong mRNA nucleotide can match up with the wrong DNA base, causing a mutation. These mutations can range due to insertion of a nucleotide, the deletion of a nucleotide, or just an error in the nucleotide. The impacts of this mutation can vary as well, from a dormant mutation or a physical or mental mutation that is continuously copied by RNA and produced.

Questions:
1. What are the four bases used in DNA?

2. Why does transcription happens?

3. Compare and contrast DNA and RNA


4.Errors sometimes occur during DNA transcription. If DNA nucleotide that contains guanine is accidentally substituted for a DNA nucleotide that contains thyamine, the error in DNA replication will be...

A. cause the cell to die when it divides
B. cause the cell to become rapidly dividing cancer cell
C. give the cell a better chance of surviving inder different conditions
D. cause the cell to produe a messanger RNA with a different nucleotide sequence.

external image dna-music.gif

SOURCES:
http://www.chrismadden.co.uk/ genetics/dna-music.gif
http://www.ehrig-privat.de/ ueg/images/dna-structure.jpg
http://rst.gsfc.nasa. gov/Sect20/dna_versus_rna_ reversed.jpg
http://www.bio.miami.edu/~ cmallery/150/gene/c7.17.7b. transcription.jpg
http://www.wiziq.com/tutorial/ 22655-ppt-taks
http://www.diffen.com/ difference/DNA_vs_RNA