Inducible Operon vs Repressible Operon
Genetic regulation is a process where certain proteins and other kinds
of stimuli tend to cause a cell to express genes or not express them.
The bacteria cell system is small system, but it carries out a lot of
activities and must do so economically and efficiently, therefore
actions of these genes must be regulated. There are two types of
regulatory systems: inducible and repressible
An operon is a cluster of genes that work together to form a
polycistronic mRNA. It consists of structural genes, a promoter
region, an operator region, and a regulatory gene. Structural genes
code for the enzymes themselves. RNA polymerase transcribes all of the
genes into a polycistronic mRNA. The promoter is the site where the
RNA polymerase binds to the DNA prior to beginning transcription. The
operator serves as the binding site for the protein called the
repressor. The regulatory gene encodes the repressor protein.
An inducible operon is an operon in which the presence of a key
metabolic substance induces transcription of the structural genes. One
example of an inducible operon is lac operon and the inducer of this
operon is lactose.
A repressible operon is an operon which always transcribes structural
genes unless a repressor is present. One example of a repressible
operon is trp operon and the co-repressor of this operon is
tryptophan.
Both lac operon and trp operon have similarities and differences
Similarities
1. Both lac operon and trp operon have structural genes with related
function are controlled by a single promoter/operator.
2. Both lac operon and trp operon have negative control regulation
system controlled by repressor. There is a regulatory gene in the
operon which encodes the repressor protein that attach to the operator
to prevent transcription.
Differences
1. In term of structure, the lac operon has three structural genes:
lacZ, lacY, and lacA. Whereas the trp operon has five structural
genes: trpE, trpD, trpC trpB and trpA.
2. In term of function, an inducible operon is generally involves in
The plasmids in lanes 3,4,8 and 9 have been digested using one restriction enzyme and had been cut at one restriction site, resulting in a linear molecule. Comparing lanes 3 and 4 to
Therefore colonies containing the non-recombinant pUC19 plasmid have a functional lacz’ gene appear blue on the agar and colonies containing recombinant pUC19 would have a non-functional lacz’ gene due to insertional inactivation and appear white on the growing medium.
coli after addition of inducer IPTG at different times. We can see from the graph that it does not cut the X axis at time 0. This is due to the fact that the lac operon was not induced by IPTG due to lack of time. The graph cuts the X axis at roughly 1 and a half minutes after adding IPTG. This indicates the time where lac operon was first induced because there was beta-galactosidase produced. From here we can deduce that production of beta-galactosidase does not take place immediately after adding IPTG but rather takes a while for all the expression staged to be passed by lac operon in order to produce beta galactosidase. From the graph we can see that for the control no beta galactosidase was produced. This is because the control contains water and the repressor was allowed to bind to the operator, causing the transcription process to initiate due to RNA polymerase II not binding to the operator. There is a positive linear relationship between the time of induction with IPTG and the amount of beta-galactosidase production in the tubes. IPTG acts as an inducer, stopping the repressor protein to bind to the operator region by binding to the repressor protein, This causes the lac operon to be
The purpose of this experiment was to discover the specificity of the enzyme lactase to a spec...
...et light. If the LAA plate glows green under exposure to ultraviolet light, then we can conclude that our unknown insert piece of DNA would be the kan gene. If it does not glow green under exposure to ultraviolet light, then then we streak the colony from our LAA plate onto the LAC plate using a sterile glass spreader. When the LAC plate is dray, we place it upside down in the microfuge rack so that it can be incubated at 37 ºC. Incubation at 37 ºC will allow the transformed bacterial cells to grow. If we see bacterial growth on the LA plate containing chloramphenicol, we can conclude that our unknown insert piece of DNA would be the cat gene, since the cat gene is resistant to chloramphenicol. Afterwards, we then grab the microfuge tube labeled NP and repeat the aforementioned steps shown above pertaining to the LA plates. This would be considered our control.
Transcription factors are proteins that help turn specific genes "on" or "off" by binding to nearby DNA.
There are 4 main mechanisms of modification and regulation of gene expression; DNA methylation, Chromatin Remodeling (architecture), Histone Modification and RNAi (interference/interactions)
Genetically modified organisms are “an organism whose genome has been altered in order to favour the expression of desired physiological traits or the output of desired biological products.” http://www.merriam-webster.com/concise/genetically%20modified%20organism%20(gmo). The United States were first approved for human consumption of genetically modified foods in 1995. The techniques used for producing the genetically developed organisms include cloning recombinant DNA technology. Primary uses of genetically modified organisms are mostly in areas of agriculture and biomedical research. GMOs compromise numerous aids to society, including enlarged crop yields and the development of fresh therapeutic agents which prevent and treat a wide variety of human diseases . However there are some concerns around the use of genetically modified organisms which include the risks stood to human health and the initiation of insecticide resistant superbugs. This essay will provide evidence to support the evidence that the genetic modifications of crops produces better results than selective breeding or mutation.
In this paper, I will negatively expose Walter Glannon’s position on the differentially between gene therapy and gene enhancement. His argument fails because gene therapy and genetic enhancement is morally impermissible because its manipulation and destruction of embryos shows disrespect for human life and discrimination against people with disabilities.
Genetic engineering depends on the location and analysis of genes on chromosomes and ultimately DNA sequencing. The early cartography of the genes used the principles of Mendelian genetics . It is assumed that alleles that are transmitted together side by side are located on the same chromosome : it is said that are connected or linkage . These genes form a bridging group - linkage group : are the same for gametes and are usually transmitted together , so they do not have independent distribution. Crossing-over occurring during meiosis may cause these alleles can be exchanged between the chromosomes of a homologous pair .
Over the past few decades, advances in technology have allowed scientists to actively manipulate the genetic sequence of an organism through a process called 'genetic engineering'. Many believe that this is a technique which we should exploit and take full advantage of as, after all, it may be the key to curing many hereditary diseases such as heart disease and cancer. It may very well be the solution to overcoming evolutionary barriers and allow us to breed new species. However, if you consider the unknown consequences we may have to face as a result of our futile experimenting, you would find that messing with a system as intricate as nature for curiosity's sake is hardly justifiable.
"The Species of the Secondary Protein Structure. Virtual Chembook - Elmhurst College. Retrieved July 25, 2008, from http://www.cd http://www.elmhurst.edu/chm/vchembook/566secprotein.html Silk Road Foundation. n.d. - n.d. - n.d.
Distinct characteristics are not only an end result of the DNA sequence but also of the cell’s internal system of expression orchestrated by different proteins and RNAs present at a given time. DNA encodes for many possible characteristics, but different types of RNA aided by specialized proteins sometimes with external signals express the needed genes. Control of gene expression is of vital importance for an eukaryote’s survival such as the ability of switching genes on/off in accordance with the changes in the environment (Campbell and Reece, 2008). Of a cell’s entire genome, only 15% will be expressed, and in multicellular organisms the genes active will vary according to their specialization. (Fletcher, Ivor & Winter, 2007).
Secondly the gene has to be cut from its DNA chain. Controlling this process are many restriction endonucleases (restriction enzymes). Each of these enzymes cut DNA at a different base sequence called a recognition sequence. The recognition sequence is 6 base pairs long. The restriction enzymes PstI cuts DNA horizontally and vertically to produce sticky ends.
I. Plasmids are important tools in molecular biology. Plasmids are small circular DNA that has the ability to enter and replicate in bacterial cells and can be used as vectors to introduce foreign genes into bacteria for cloning and sequencing. Any gene must be inserted into an appropriate location of a plasmid to be expressed. The importance of a plasmid is in the step of cloning and sequencing when the construction of a recombinant DNA molecule occurs. The target gene fragment is ligated to a plasmid, and becomes recombinant DNA. Then the plasmid can replicate autonomously in an appropriate host organism.