Monday, 28 December 2015
Sunday, 27 December 2015
Saturday, 26 December 2015
Friday, 18 December 2015
What is a GMO?
o A genetically modified organism (GMO
Monday, 28 December 2015
Sunday, 27 December 2015
Saturday, 26 December 2015
Friday, 18 December 2015
What is a GMO?
o A genetically modified organism (GMO) is an organism (plant, animal, bacteria or virus) whose genetic makeup has been modified for a particular purpose.
o The organism does not occur naturally in this modified state.
o For example, a plant can be modified to carry an additional gene found in another living thing (such as a bacteria) to protect itself against insect pests.
o Genes carry the information or the “recipe”, in the sequences and structures of DNA, which gives the organism its specific characteristics.
o Genes can be added, removed or changed, using modern biotechnology methods.
o Because Genes are common to life on earth, genes can be transferred from one organism to another and even between non-related species.
o This manipulation can produce a product with new characteristics which may have advantages.
How are GMOs useful to us?
- GM (genetically modified) plants are already being cultivated as crops and consumed by humans and animals.
- Using genetic engineering, new improved varieties of crops can be produced more quickly than with conventional breeding methods.
- Crops can be modified to have valuable characteristics such as tolerance to drought and herbicides, resistance to disease and insects, as well as improved nutritional content.
- · Insulin as a treatment for diabetes was the first commercial healthcare product produced by GMOs.
- · Bacteria were genetically modified to have a copy of the human insulin gene, and the protein is synthesized by the bacteria.
- · GMOs can produce other medicines such asgrowth hormone.
- · GMOs are used in current vaccines such as Hepatitis B (produced by yeast), and new vaccines are being developed using GMO technology.
- · In the future, plants may even be engineered to contain the vaccines so that we may be able to eat our vaccinations rather go for an injection.
- · In the future, GMOs may be used for gene therapy to correct certain genetic conditions.
- · GM cotton has been created to be resistant to insect attack to improve the yield of the crop.
Adaptive immunity is capable of recognizing and selectively eliminating specific foreign microorganisms and molecules
(i.e., foreign antigens).
Unlike innate immune responses, adaptive immune responses are not the same in all members
of a species but are reactions to specific antigenic challenges.
Adaptive immunity displays four characteristic attributes:
- · Antigenic specificity
- · Diversity
- · Immunologic memory
- · Self/nonself recognition
The antigenic specificity of the immune system permits it to distinguish subtle differences among antigens.
Antibodiescan distinguish between two protein molecules that differ in only a single amino acid.
The immune system is capable ofgenerating tremendous diversity in its recognition molecules,
allowing it to recognize billions of unique structures on foreign antigens.
Once the immune system has recognized and responded to an antigen, it exhibits immunologic memory;
that is, a second encounter with the same antigen induces a heightened state of immune reactivity.
Because of this attribute, the immune system can confer life-long immunity to many infectious agents after an initial encounter.
Finally, the immune system normally responds only to foreign antigens, indicating that it is capable of self/nonself recognition.
The ability of the immune system to distinguish self from nonself and respond only to nonself molecules is essential, for, as described below, the outcome of an inappropriate response toself molecules can be fatal.
Adaptive immunity is not independent of innate immunity.
The phagocytic cells crucial to nonspecific immune responses are intimately involved in activating the specific immune response.Conversely, various soluble factors produced by a specific immune response have been shown to augment the activity of these phagocytic cells.
As an inflammatory response develops, for example, soluble mediators are produced
that attract cells of the immune system.
The immuneresponse will, in turn, serve to regulate the intensity of the inflammatory
Through the carefully regulated interplay of adaptive and innate immunity, the two systems work
together to eliminate a foreign invader.
The Adaptive Immune System Requires Cooperation Between Lymphocytes and Antigen-Presenting Cells
Wednesday, 16 December 2015
Waste water and sewage treatmentItruduction;
While many ancient civilisations had an appreciation of the need to protect the quality of water to be used for human consumption, it was not until 1855 that it was demonstrated that cholera was transmitted by water contaminated by faeces.
A similar route for typhoid fever was shortly to
be demonstrated. By the end of the nineteenth century, the microbial ecology of many human diseases had been shown to have an anal–oral route of transmission, which finally confirmed the health hazards associated with water contaminated with faeces. The introduction of sewage systems in