The Cell: Producing Proteins

The Cell: Producing Proteins

Its been a while since I delved into the the intricacies of the cell. However, one of my Christmas gifts this year was a recently published Creation science book about the problems genetics poses to Darwinian evolution. While reading this book. I began to discover some very interesting facts about protein synthesis. I followed that up by doing some research of my own. This article is a culmination of what I learned over the course of that research. This article will follow the process of protein synthesis from DNA transcription to protein formation and discuss where the process fits in the origins debate.

Protein synthesis is essential to the cell.  Proteins are the building blocks of life. They are found in innumerable places throughout the cell. However, like anything else, proteins are not immortal. They undergo wear and tear and eventually degrade. If they were not replaced, the cell would quickly become incapacitated and die.  However, the cell replaces proteins as they degrade through the protein synthesis process. This process begins in the nucleus of the cell. This is where the DNA of the cell is stored.  In order to begin the process of protein synthesis, the double helix of DNA must be opened so that the information stored inside can be copied. This process is referred to as transcription.

Transcription is an essential part of protein synthesis process. In order to begin transcription, a special enzyme called helicase moves along the portion of the double helix which is to be transcribed, breaking the chemical bonds which hold it together. As this happens, RNA polymerase follows in its wake. The function of RNA polymerase is to form a new RNA strand which is complimentary to the DNA strand being transcribed.  The complimentary strand of RNA is called messenger RNA or mRNA.  The cell then rezips the DNA double helix back together and sends the mRNA strand out of the nucleus and into the cytoplasm of the cell for the next necessary process: translation.

The translation process takes the information from transcription of DNA and turns it into something the cell can use. This process only works because of the way DNA is coded. DNA is coded in three nucleotide codons, each one coding for a specific amino acid, which are the building blocks of an individual protein.  The below chart shows what each codon codes for.

Codontable1.PNG

Thus a sample strand of mRNA might read as follows: “AUG, UCU, ACU, ACG, UGG, UGA.”  Using the chart above this would translate as “Methionine(meaning start) Serine, Threonine, Threonine, Tryptophan, stop.” Obviously this is a very simplistic strand of mRNA but it illustrates the process well. Each mRNA strand contains a start codon at the beginning of it, and a stop codon at the end of it. However, before the proteins can be synthesized, the information on the RNA strand must be translated into amino acid chains. This translation process takes place in a specialized cellular organelle called a ribosome.  The ribosome is covered in specialized RNA strands called ribosomal RNA or rRNA.  One of these rRNA binds with the start codon on the mRNA. Once this occurs, a third kind of RNA, transfer RNA or tRNA binds to the mRNA. The tRNA has a special attachment point atop each of its codons, to which an individual amino acid will attach.  Each codon’s amino acid binds together as they tRNA codons bind with the mRNA codons. This process goes on through dozens of ribosomes throughout the cell until an amino acid chain forms. This polypeptide as it is known is not a protein yet. To become a protein, the newly formed amino acid chain must be folded into a three dimensional structure.

Getting a three dimensional structure out of a straight line of amino acids is no easy task. A protein’s three dimensional structure is called its native conformation. This is where the ribosome becomes very important. It takes the long polypeptide chain and folds it carefully into its native conformation. It is very important that the protein fold correctly. If it misfolds, it will not be functional and in some cases will cause deformities and diseases in the cell. A protein that was not folded correctly is called a prion. However, if folded correctly the protein will be used in any number of cellular organelles and will be beneficial to the cell.

The protein synthesis process is a huge problem for evolutionists. The first issue they have with the process is that it creates the proverbial “chicken and egg” problem. Essentially proteins are required to make proteins. Ribosomes are composed of more than just rRNA. Their base structure is formed of proteins with the rRNA being embedded in the ribosomal structure.  Recall that ribosomes are required to both anchor mRNA and fold the resulting polypeptides into proteins. Thus proteins must exist in order for new proteins to form. Unless ribosomes exist, new proteins would not form and the cell would die. However, ribosomes themselves would not exist without proteins.  Both must have independently formed simultaneously, rather than as a result of a slow gradual process.

Further, the whole process must have formed simultaneously or the process is useless. What good is tRNA without mRNA to bind to? Why have ribosomes with no amino acids to fold into proteins? The entire system must exist at once or the process is useless and, in some cases impossible. The process of protein synthesis demands a preexisting system of interconnected parts that all came into existence simultaneously, not piece by piece over long periods of time.

Creationists have no problems with protein synthesis. The entire process lines up exactly as we would expect to see it work if it had been designed to work that way from the beginning. Protein synthesis shows forth the design of the Master Designer in even the smallest details of the cosmos.

 

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