Contact Us
Sign In / Sign Up for FREE
Go to advanced search...

Cell Biology - Essay Example

Comments (0) Cite this document
coli. HisP is an allosteric protein whose activity is modulated by histidine. Upon binding histidine, HisP alters its conformation, dramatically changing its affinity…
Download full paperFile format: .doc, available for editing
GRAB THE BEST PAPER97.9% of users find it useful
Cell Biology
Read TextPreview

Extract of sample "Cell Biology"

1 A gene regulatory protein called HisP regulates the enzymes for histidine biosynthesis in the bacterium E. coli. HisP is an allosteric protein whose activity is modulated by histidine. Upon binding histidine, HisP alters its conformation, dramatically changing its affinity for the regulatory sequences in the promoters of the genes for the histidine biosynthetic enzymes.
A. If HisP functions as a gene repressor, would you expect that HisP would bind more tightly or less tightly to the regulatory sequences when histidine is abundant? Explain Answer.
If HisP functions as a gene repressor, I would expect to bind more tightly to the regulatory sequences in the presence of abundant histidine. As a suppressor, HisP would function to downregulate the expression of the histidine biosynthetic enzymes in the presence of ample histidine, since the cell does not need to synthesis histidine under those conditions.
B. If HisP functions as a gene activator, would you expect that HisP would bind more tightly or less tightly to the regulatory sequences when histidine levels are low? Explain answer.
If HisP functions as a gene activator, I would expect it to bind more tightly to the regulatory sequences under conditions with low levels of histidine. As a gene activator, HisP would function to increase the expression of genes necessary for the biosynthesis of histidine. This would be more necessary and beneficial to the cell under conditions of low histidine.
2. In class we talked about how bacterial cells can take up the amino acid tryptophan from their surroundings, or if the external supply is insufficient, they can synthesize trytophan by using enzymes in the cell. In some bacteria, the control of glutamine synthesis is similar to that of tryptophan synthesis, such that the glutamine repressor is used to inhibit the transcription of the glutamine operon, which contains the genes that code for the enzymes required for glutamine synthesis. Upon binding to cellular glutamine, the glutamine repressor binds to the site of the promoter of the operon.
A. Why is glutamine-dependent binding to the operon a useful property for the glutamine repressor?
By repressing the expression of the glutamine operon in the abundance of glutamine, as when the repressor molecule is bound to glutamine, the cell can conserve energy by not synthesizing a molecule that is already in abundance in its environment. When the supply of glutamine drops, the number of repressor molecules bound to glutamine, and hence repressing the expression of the glutamine operon, drops as well. This allows the cell to express the glutamine operon in order to raise levels of glutamine through its own biosynthetic pathway.
B. What would you expect to happen to the regulation of the enzymes that synthesize glutamine in cells that express a mutant form the glutamine repressor that cannot bind to DNA?
The regulatory mechanism would fail because no allosteric (or other) changes induced by glutamine binding to the repressor molecule would allow it to bind to the glutamine operon promoter and cease synthesis of it. As a result, assuming no other regulatory mechanisms prevented it, the cell would continuously synthesize the glutamine operon, even in the presence of abundant glutamine.
C. What would you expect to happen to the regulation of the enzymes that synthesize glutamine in cells that express a mutant form of the glutamine repressor that binds to DNA even when no glutamine is bound to it?
Once again the normal regulatory mechanisms control the expression of the glutamine operon would fail. If the repressor was continuously bond to the promoter region, even in the absence of glutamine, the cell would not synthesize sufficient glutamine in its absence in the cell’s environment.
3. We have discussed how the lac operon (see figure) is controlled by both the CAP activator protein and the lac repressor. You create cells that are mutant in the gene coding for the lac repressor so that now these cells lack the lac repressor protein under all conditions. For these mutant cells, state whether the lac operon will be ON or OFF under the following situations.
A. In the presence of glucose and lactose.
B. In the presence of glucose and the absence of lactose.
C. In the absence of glucose and the absence of lactose.
D. In the absence of glucose and the presence of lactose.
4. The gene for a hormone necessary for insect development contains binding sites for three gene regulatory proteins called A, B, and C. Because the binding sites for A and B overlap, A and B cannot bind simultaneously. You make mutations in the binding sites for each of the proteins and measure the hormone productions in cells that contain equal amounts of the A, B, and C proteins. The results of your studies are summarized in the figure. In each of the following sentences, choose one of the phrases within square brackets to make the statement consistent with the above results.
A. Protein A binds to its DNA binding site [more tightly/less tightly] than protein B binds to its DNA binding site.
B. Protein A is a [stronger/weaker] activator of transcription than protein B.
C. Protein C is able to prevent activation by [protein A only/protein B only/both protein A and protein B]. Read More
Cite this document
  • APA
  • MLA
(“Cell Biology Essay Example | Topics and Well Written Essays - 500 words - 1”, n.d.)
Retrieved from
(Cell Biology Essay Example | Topics and Well Written Essays - 500 Words - 1)
“Cell Biology Essay Example | Topics and Well Written Essays - 500 Words - 1”, n.d.
  • Cited: 0 times
Comments (0)
Click to create a comment or rate a document


Cell Biology

Average-sized molecules travel through the gel with different degrees of facility. Electrophoresis is done in a thin vertical slab of polyacrylamide. The course of protein movement is from top to bottom. Protein molecules can be isolated on the basis of their individual mass through use of electrophoresis in a polyacrylamide gel under protein denaturing process. The mixture of protein macromolecules is initially denatured in a homogeneous mixture of sodium dodecyl sulfate (SDS), which is an anionic emulsifier with the ability of disrupting almost all noncovalent interactions in native proteins macromolecules. SDS forms complexes with the denatured proteins which are then subjected to electrophoresis. After the process of electrop...
7 Pages(1750 words)Essay


...A diploid sexually reproducing organism contains five pairs of chromosomes that do not undergo homologous recombination during meiosis. If the chromosomes are distributed independently during meiosis, how many different types of sperm or egg cells can a single individual of this species produce? There are five different types of eggs or sperms. 2 Indicate whether the following are involved in meiosis, mitosis, both, or neither. A. DNA replication ____ both in mitosis & meiosis ___________________ B. Spindle formation ____ both ___________________ C. Bivalent _____ in meiosis __________________ D. Chromosome condensation _____ both __________________ E. Maternal chromosome segregation to one cell ____ neither...
2 Pages(500 words)Essay

The Difference between Sickle-Cell Anemia and Malaria Resistance

It has been found that this disease is very well equipped in resisting malaria or in other words sickle cell anemia is a fairly effective resistant against malaria. The carrier of this always carry an amount of this disease in their blood cell as this genetic disease is very recessive in nature. For this reason this complementing disease is referred to as heterozygote advantage.

This phenomenon happens because as a rule the malaria parasite needs to be embedded in blood cells to reproduce but the blood cell of an infected person resists the parasite plasmodium to settle down. Thereby depriving the parasite to reside and multiply. In this process, the sickle cell disease prevents the carrier from probable infection of ma...
6 Pages(1500 words)Assignment

Biology Data-based Questions

Potassium or K and Calcium or Ca has shown greater Mean Residence Time in rainforest chaparral when compared to temperate forests whereas Phosphorus or P demonstrates maximum variance in Mean Residence Time.

In general, plant productivity and Mean Residence Time are such that one increases whilst the other decreases. In subarctic regions, there is low plant productivity and greater Mean Residence Time.

In tropical forests, the mean residence time of nutrients is influenced by higher temperatures than in subarctic forests. Therefore, there is a vast difference in the MRT of nutrients pertaining to the tropical rainforest and the subarctic forest.

Nuclear fission weapons tests in 1961 released radioa...
10 Pages(2500 words)Assignment

How Have Gene Therapy and Stem Cell Technology Changed the Face of Medicine

... offer new insights into the development of cells and tissues that could not be observed directly in the human embryo or comprehended through clinical observation of animal models. Research on stem cells could shed more light on basic development biology and lead to better understanding of genetic problems such as abnormal births, pregnancy loss and infertility. Such studies could also provide answers to the complex processes of normal and abnormal human development. Stem cell technology could help in studying a wide range of human diseases on animal models. Animal stem cells, especially embryonic stem cells could be engineered to incorporated human mutated genes associated with particular diseases, and then transferred to the experimental...
9 Pages(2250 words)Coursework

What Are the Ethical Postives and Negatives of Stem Cell Research

...Bioethical issues have taken on a fundamental importance in our society during the past century. As science and technology have collectively pushed the boundaries of what is possible, or what is conceivable, ethics should never be left out of the picture. Although, to quote Immanuel Kant’s famous formulation, an ought implies a can, a can does not imply an ought. In other words, simply because humans have the capability of performing some deed, as novel or interesting as it is, we must first question whether it is the right thing to do. A particularly contentious issue in bioethics is that of stem cells, which is largely opposed by individuals who see the world normatively in one state of mind. Meanwhile, others may see the same issue...
8 Pages(2000 words)Term Paper

Using Cell Phones while Driving

... “Using Cell Phones while Driving?” Introduction Technological telecommunications advancement in the past twentieth century has seen the introduction of cellular phone as a versatile and adaptable gadget for communication. While cellular technology is innovatory gadget of communication rather than for transportation, their potential effect on the transportation sector is of a sizeable magnitude. Today worldwide, the possibility of over twenty million automobile operators having a one-touch dial opportunity to place a phone call, receive or send a short email or message while on the steering wheel is not a phenomena that easily escapes the eye. The use of cell phone on the roads has become so popular amongst motorist, to support...
9 Pages(2250 words)Coursework

Cell Phone Usage and Texting While Driving

...Cell Phone Usage/Texting While Driving s Driving while texting is a public safety issue, that needs adequate attention. The problem has been accelerated as more teenagers and adults with texting habits become drivers that are licensed. The strategies to curb this behavior are multidimensional hence helping in condemning such a behavior both socially and legally. This has been done through the provision of alternative and safer ways such as the use of modern technologies, awareness creation and banning the behavior by various state governments. Cell Phone Usage/Texting While Driving The use of cell by individuals while driving is an extremely heated and controversial topic for debate all over the globe. Annually, millions of people...
7 Pages(1750 words)Assignment

Why Using a Cell Phone During Driving Should Be Banned

...Using a Cell Phone Should Be Banned during Driving: The technology that we attain provides us with a large number of benefits and advantages. It makes tasks easy. However, their use and abuse is largely subjective in nature and depends on the users and the way they use it, as well as when they use it and in what manner. Various technological means have been attained over the past years, such as GPS, stereos in the car, mobile phones. Mobile phone is no exception and it is a ubiquitous device in modern times that is part of every house, every pocket, every building, yet its misuses are millions and dangerous at the same time. Mobile phone usage while driving is a serious concern in modern day. Many incidents get reported due to the reason...
6 Pages(1500 words)Term Paper

The Regulation of Cell Phone Use While Driving

...Should Regulations Regarding the Use of Cell Phones While Driving be Standardized? Marketa Burnett Dr. Christine Barham Research & Writing Introduction Of top of 1,060 injury cases associated with road accidents, the Center for Disease Control and Prevention estimated that at least nine people die each day by “distracted driving” (CDC, 2014). In line with this, Jacobson and Gostin (2010) pointed out that “sending text messages, calling from cell phones, watching videos, or “searching the Internet” are among the few common distractions while driving. To effectively reduce the number of road accidents caused by distractions in driving, a total of 39 different states in the US have already ratified some form of laws with regards to the need...
6 Pages(1500 words)Term Paper

Glaucoma: Biology and the Role of Biomechanics

The initial forms of glaucoma like aniridia are passed on as autosomal recessive or dominant characteristics, while, the adult glaucoma forms like low tension glaucoma are passed on as intricate traits (Calkins & Horner, 2012). A study conducted by Foster et al., (2002) suggests that glaucoma can either be familial, sporadic or inherited
Three genes have been identified and linked with glaucoma. They are optineurin, myocilin, and WD Repeat-containing Protein 36. The gene, optineurin has been associated with primary open-angle glaucoma. Its interaction with other proteins has led to the suggestion that it hinders the presence of tumor necrosis factor A. (Sripriya, et al., 2007).
Myocilin is said to cause around 4% of...
6 Pages(1500 words)Literature review

Stem Cell Research Policies Around the World

Among these, the use of embryonic stem cells has been the most debated and opposed as scientists maintain that of the many potential sources embryonic stem cells have a greater degree of pluripotency and hence could be a good source of a variety of cell types, while at the same time religious groups have vehemently opposed the use of embryos for research (Stem Cell Information, 2011). While a large community of the medical and scientific fraternity has acknowledged its importance and wide implications in treatment, religious groups seem to have a varied status with regard to stem cell research. However, considering the enormous benefits that humans stand to gain from the use of stem cells due to its inherent ability to liberate hu...
17 Pages(4250 words)Research Paper
sponsored ads
We use cookies to create the best experience for you. Keep on browsing if you are OK with that, or find out how to manage cookies.

Let us find you another Essay on topic Cell Biology for FREE!

Contact Us