Gene Expression in Eukaryotes

Transcription is the formation of an RNA strand from a DNA template within the nucleus of a cell. There are four nucleotides of DNA. These are adenine, cytosine, guanine and thymine. These nucleotides are transcribed to form messenger ribonucleic acid (mRNA) consisting of nucleotides made of adenine, cytosine, guanine and uracil. This transcription from DNA to mRNA happens by an RNA polymerase II. This newly created mRNA is read in the 5' to 3' direction in sets of 3. These sets are called codons. Each mRNA also has a cap and end. On the 5 prime side is a methylated guanine triphosphate and on the 3 prime is a poly A tail. Messenger RNA then moves to the cells cytoplasm and through the cells ribosomes for translation. Messenger RNA is matched to molecules of transfer RNA (tRNA) in the ribosomes to create amino acids. These amino acids subsequently form an amino acid chain. (Osuri, 2003) A visual representation of this can been viewed in figure 3.

1) DNA programs protein production in the cytoplasm by transferring its coded information to a molecule called RNA (mRNA). The RNA then carries the order to build this type of protein from the nucleus to the cytoplasm.

Also, regulation of proteins occurs at the level of DNA as well as on other levels. In some cells, certain sections of DNA are bundled tight in a mass of proteins, in such a way that no RNA (and thus no protein) can be made from them. This turns off those genes. In other sections, only a few proteins might be keeping the DNA turned off, so that it could quickly be unravelled and used to make proteins.

Since DNA has the instructions for making protein we usually wonder how is it able to make ribosomes if DNA is stored within the nucleus. This is when a handy tool comes in called transcription and copies the DNA into mRNA so it can be reached outside of the cell.

Translation is a task that makes ribosomes synthesize proteins utilizing mRNA transcript made during transcription. In the begining of this task mRNA attaches it self to a ribosome so that it can be reveal a codon (three nucleotides).

RNA processing: In eukaryotic cells, introns, non-coding regions of RNA, are removed and a tail and a cap is added to RNA to help its movement.

Transcription is where I translate the list of nitrogenous bases in the mRNA at the cell's ribosomes. I want to tell you what a codon is and tell you my five other journeys. A codon is where each three nitrogenous bases in an mRNA that helps a specific amino acid added to me the protein butterfly. My adventure begins when a ribosome comes together to an mRNA in the cell's cytoplasm. Then on my journey my BFF codon goes throught the ribosome, tRNA shares with the amino acid to the ribosome. My other friend anticolon does a great job of putting three nitrogenous bases in tRNA to help the codon in mRNA. My third adventure was where tRNA bring a type of amino acid; then she breaks the code in the mRNA into a guide of amino acids. Following is my second to last adventure was when my friend ribosome and rRNA makes the amino acid together. My last adventure was the funnest because this is the part where I turned into a protein butterfly. :) Here is how the ending goes: My other friend protein chain goes raises til the ribosome gets a end codon on the rRNA. After that ribosome leaves equally mRNA and me the protein

translation begins with the reading of the first triplet. Small tRNA molecules bring in the

It provides a base triplet, a sequence of three bases on one of the strands of DNA, that code for one amino acid. The sequence of base triplets on DNA molecules determines the order of the amino acids on the protein chain. In the first phase of transcription, the first process of protein synthesis that occurs in the nucleolus, a portion of a DNA molecule unwinds and serves as a template. Free nucleotides floating in the nucleoplasm pair up with their complimentary bases on the DNA strand.

The nucleus creates mRNA and the mRNA goes through the nuclear pores into the cytoplasm. The mRNA is transcribed the from the DNA. Once the mRNA enters the cytoplasm it is translated by ribosomes, than the corresponding amino acids come and form proteins.

During this lab the Drosophila cells had to go through certain processes so we could insert the double stranded RNA. The first process is replication. Replication is a semiconservative process in which two strands of DNA are created from one double strand of DNA. The total production is four single strands of DNA, each strand made from one old and one newly made single strand. Replication first starts with a cluster of proteins called a protein complex. When a protein complex binds to a section of DNA with adenine and thymine repeats, called regions of replication, it creates a ‘bubble’ between the DNA. With a small opening in the DNA an enzyme called helicase comes in and makes the bubble larger. In order to keep the DNA from joining back together a protein binds to the open DNA. Primase, another enzyme, lays down little strands of RNA for an enzyme called DNA polymerase III to bind to so it can add new complementary nucleotides to create a new segment of single stranded DNA. DNA Polymerase III can only work

Gene expression is the ability of a gene to produce a biologically active protein. This process is regulated by the cells of an organism, it is very important to the survival of organisms at all levels. This is much more complex in eukaryotes than in prokaryotes. A major difference is the presence in eukaryotes of a nuclear membrane, which prevents the simultaneous transcription and translation that occurs in prokaryotes. Initiation of protein transcription is started by RNA polymerase. The activity of RNA polymerase is regulated by interaction with regulatory proteins; these proteins can act both positively, as activators, and negatively as repressors. An example of gene regulation in cells is the activity of the trp operon. The trp

One of the fundamental discoveries of the 20th century was that DNA was the genetic code’s physical structure (Watson & Crick, 1953) and, since then, many studies have disclosed the complicated pattern of regulation and expression of genes, which involve RNA synthesis and its subsequent translation into proteins.

Transcription is where DNA is transcribed into RNA which then can be pass to the ribosome’s to act as a template for protein synthesis. Before transcription can begin DNA must unwind and the two halves of the molecule much come apart so exposing the base sequence. This process begins when a region of a two DNA strands is unzipped by enzyme called RNA polymerase attaches to the DNA molecule at the imitation site.

The formation of a protein begins in the genes, which contain the basic building information for all parts of living organisms. There are four DNA nucleotides that make up genes: A, T, C, and G. A codon is any arrangement of three of these nucleotides. Each triplet of nucleotides codes for one amino acid. First transcription will begin in the nucleus where mRNA will transcribe the DNA template. During both transcription and translation, there are three steps. The first step in transcription is initiation where RNA polymerase separates a DNA strand and binds RNA nucleotides to the DNA. RNA nucleotides are the same as DNA ones except that U replaces the T. The second is just the elongation of the mRNA. The third step of transcription is termination. This occurs when RNA polymerase reads a codon region and the mRNA separates from the