TRANSCRIPTION AND TRANSLATION NOTES!

Section: 6.2 Transcription: Synthesizing RNA from DNA

• Transcription is can be defined as the synthesis of singles stranded RNA from a double stranded DNA template. The DNA is what stores the information needed for reproduction a survival, however, there must be a method for reading this information. To utilize this information, transcription is needed to accurately copy a smal section of DNA into RNA. RNA are simple stranded polynucleotide molecules that contain the four bases of adenine, thymine, guanine and cytosine with alternating phosphate groups and ribose sugars. 

Here's the process of transcription broken down into three stages: Initiation, Elongation, and Termination:

Initiation

• Synthesis of RNA occurs in the nucleus.
• Transcription starts with assembling the transcription machinery and locating the site to begin the transcription process. The strand being transcribed is referred to as the antitsense strand or template strand and the complementary strand that is not being transcribed is known as the sense strand or coding strand. 
• RNA polymerase are the enzymes that catalyzes the synthese of RNA from a DNA template. The RNA polymerase binds to a promoter region on the DNA which signals where the translation will begin. It is signaled by a TATA box on the coding strand of the DNA and this is where the RNA polymerase will bind. 
• Before translation starts, the DNA strand needs to be unwound. 

Elongation

• During the elongation phase, the RNA polymerase will will begin to synthese the RNA that is complementary to the DNA with uracil replacing the thymine in the direction of 5' to 3'.  
• RNA polymerase follow one another to produce many copies of the RNA.
• Since there is no proof reading stage in translation, the process is much faster than that of DNA replication. This is usually because, there is not much risk with mistakes as an error in transcription will only result in a single protein failure so the speed of RNA production weighs heavier then accuracy in this case.  

Termination 

• Find AAAAAATAAAAAAA on the coding strand for termination of transcription 
• Since mRNA is single stranded, it is weaker than DNA. It is more prone to damage so the mRNA that results from transcription is called precursor mRNA. To make it into a mature mRNA, a 5' G-cap and a 3' poly-A-tail are added for it to survive longer in the cytoplasm. 
• Also, by a process called splicing, spliceosomes remove the introns (non-coding regions) so that the RNA is only left with the remaining exons (coding regions). Lastly, the exons are rejoined together. 

Section: 6.3 Translation: Synthesizing Proteins from mRNA

• Translation is the synthesis of protein from an mRNA template. This occurs in the cytoplasm.
• mRNA contains the genetic information that determines the amino acid sequence of a protein while tRNA are responsible for delivering the amino acids to the translation machinery with great accuracy and precision. Each tRNA contains an anticodon that base pairs with a codon on the mRNA and that it how the correct amino acid is coded for. The amino acid is connect to an acceptor stem and the enzyme aminoacyl-tRNA-synthetase will attach the appropriate amino acid to the tRNA

Like transcription, translation can also be categorized into three stages which are Initiation, Elongation, and Termination 

Initiation  

• During the initiation phase of translation, the components of the ribosomal sub units, mRNA and tRNA assemble. The ribosomal sub unit will attach to the start codon (AUG).
• A reading frame will determine how the codons are read. There are three binding sites for tRNAs and they are the peptide site, the amino acid site and the exit site.
•  The first amino acid will be attached to the P-site and the while the A-site awaits the next tRNA carrying the amino acid. The amino acids will form a peptide chain and the tRNA will be uncharged as it no-longer carries any amino acids. 

Elongation

• During the elongation phase, protein synthesize and the chain becomes longer one amino acid at a time. There amino acids are linked by peptide bonds.
• The polypeptide chain will move from the tRNA on the P-site to the tRNA on the A-site. Each time this occurs, the chain is one amino acid longer.
•  tRNAs the exit from the P-site to the E-site. The tRNA from the A-site will then move to the P-site and another tRNA will occupy the A-site. The process will repeat until the chain is complete. 

Termination 

• During termination, a stop codon is reached on the mRNA and the poly peptide and the components that came together in the initiation phase disassembles. 
• The polypeptide is then released to carry out its purpose. 

Gene Expression 

• The expression of a gene refers to the synthesis of a protein that is encoded by that gene. It involves transcription to form mRNA which is used as a template for protein synthesis. Gene expression governs the development of living organisms. 

DEAF BY DESIGN

Unless One lives by the belief of ignorance is bliss, I think the ability to alter genetic codes is a tremendous breakthrough in science and a blessing for humanity. However, like many great things, it can also be abused but this does not change all the possibilities that it brings. One of the many benefits that spins off from the ability to alter genetic codes is the ability to screen for abnormalities in fetuses. This is the answer to the prayers of parents-to-be everywhere as genetic screening and prenatal testing seem to provide a cookie cutter perfect solution in preventing illness and disability with a new born. It also allows the parents to select or prevent certain traits in their children.

In the article Deaf by Design, it speaks of cases which baffles my mind and challenges my beliefs. In the article, a deaf pair of parents uses this technology to screen for the possibilities of having a deaf child and is unhappy when they are gifted with a hearing one. It took my brain a few minutes to process this and come finally come to the conclusion that the parents were clearly not in the right state of mind. It is down right child abuse, trying to introduce the poor little thing into the bitter harsh world without a fighting chance because the parents seem to like being crippled. At the same time, hearing parents unhappy about having a deaf child seems perfectly normal to me. After watching the documentary Sound and Fury,  I was able to gain some insight as to why these deaf parents would think in such a way. To people who have grown up in silence, the deaf community must seem like a small safe haven surrounded by a larger world in which they are outsiders. It seems then natural for deaf parents to want to place their child under the circumstances in which they believe will provide a safe home opposed to the scary hearing world in which they cannot be a source of guidance in and may just fade away into the background of the child's life.

In the video, Heather's father makes me question what a disability truly is by saying that he sees being deaf as a blessing and is happy that all of his children are deaf. A disability to me is defined as a physical or mental handicap that prevents one from living a normal life and puts one at a disadvantage. Perhaps this term was ment to be more relative? Well, as much as this video has opened my mind with regards to the relative term of disability, I still believe that children such as Heather are at a disadvantage in the real world. I think that if a child wants it, it shouldn't be up to the parents to stop their decision to fix their disability. In Heather's case, a cochlear implant would be her second chance at leading a normal life. At only five, she already knows what it feels like to not belong to a majority and brave for a way out. However, her parents sees the cochlear implant as an invasive surgery which will sweep Heather away from the deaf community and inevitable their lives as well.

Heather's father makes references to religion stating that a parent choosing deafness for their children is no different that a parent choosing the religion of their children. I think this is utterly wrong to say because as the child grows, he/she has the ability to leave behind their religion but a deaf child can not just wake up one day and choose to leave behind their disability. I think it is Heather's parent's duty as her care givers to make  allow her to the choice of having the cochlear implant. It is their responsibility as parents to make her transition into the hearing world with the cochlear implant as easy as it can be. If it goes against their beliefs and they really don't want to do it, then they should do it out of love as hearing will open so many doors for their little girl. She can become limitless to her possibilities in life. Her position in a family of deafness should not define her future so even if she is the only hearing member among her siblings it is still in her best interest to get the implant. However, if it were my say, all of the children should get the implant.