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Wednesday 17 August 2011
BAC ( Bacterial artificial chromosome)
BAC are simply plasmids desigened for the cloing of very segments of DNA. They generally includes selecatable markers such as chloramphenicol resistance (MR), as well as a very replication origin (ori) that maintains the plasmid at one or two copies per cell. DNA framents several hundred base pairs in the lenght are cloned into the BAC vectors. The bacterial used as host for recombinnat BAC have mutation that comprises the structure of the bacteria cell wall, facilitating the uptake of these large DNA molecules.
COSMID
The way in which DNA is replicated is of particular interest in the development of larger insert cloning vectors termed cosmid. Cosmids are plasmids that contain minimum of 250 bp of DNA consisting of the cos site (sequnence yielding cohesive ends.) these are especially useful for the analysis of highly complex genome mapping projects.
Cosmid vectors have been constructed that incorporate the cos .sites from bacteriophage lemda and also the essential feature of a plasmid , such as the plasmid origin of replication , a gen for drug resistance and several unique restriction sites for insertion of the DNA to be cloned when a cosmid , the produducts will include cocatamers of alternating cosmid vector and inserts. The only requirement for a length of DNA to be packed into viral heads, therefore, is that it should contain cos site spaced the correct distance apart in practice tis spacing can range between 37 to 52 kb. Such DNA can be packed in vitro if is very small, inserts of about 40kb in lenght will be most readily packaged. Once inside the cell, the DNA recircularrises through its , and from, then own wards behave exactly like a plasmid.
Cosmid vectors have been constructed that incorporate the cos .sites from bacteriophage lemda and also the essential feature of a plasmid , such as the plasmid origin of replication , a gen for drug resistance and several unique restriction sites for insertion of the DNA to be cloned when a cosmid , the produducts will include cocatamers of alternating cosmid vector and inserts. The only requirement for a length of DNA to be packed into viral heads, therefore, is that it should contain cos site spaced the correct distance apart in practice tis spacing can range between 37 to 52 kb. Such DNA can be packed in vitro if is very small, inserts of about 40kb in lenght will be most readily packaged. Once inside the cell, the DNA recircularrises through its , and from, then own wards behave exactly like a plasmid.
Problems in large scale culture of plnt cells
Large acale culture of plant cells for commercial applications like biochemical, artificail seed etc. Producation presents serveral problems which are summarised below.
1. Plant cells have much slower growth rates than bacteria anf fungi, therfore, larger reactores and longer fermentation times are necessary.
2. The long fermentation time increases the risk contamination.
3. Plant cells are rather sensitive to shear. Therefor, fementers with conventional mechanical stirring are not suitable for their culture. Bioreactors having specially designed mechanical stirrers airlift fermenters are far more suitable.
1. Plant cells have much slower growth rates than bacteria anf fungi, therfore, larger reactores and longer fermentation times are necessary.
2. The long fermentation time increases the risk contamination.
3. Plant cells are rather sensitive to shear. Therefor, fementers with conventional mechanical stirring are not suitable for their culture. Bioreactors having specially designed mechanical stirrers airlift fermenters are far more suitable.
Preparation of chimeric DNA
The main purpose of genetic engineering is to insert a DNA of inserest into a vector DNA so that the DNA fragment replicates alongwith the vector. The hybrid combination of two fragment of DNA is referred to as recombinant DNA or chimeric DNA ( chimera is a monster in greek mythology that has a lion’s head, a goat’s body and a serpent’s tail. This may be comparable to narsimha in indian mythology)
A fragment of target DNA (for human) and the vector DNA (for plasmid) produced by a specific restriction endonuclease, possing stricky ends, can be conveniently used- for the preparation of chimeric DNA. The human DNA and vector DNA with complementary sequences are annealed. The enzyme, namely DNA ligase, seals(ligates) the DNA fragments to finally produce reduce recombinant DNA.
For the ligation of two DNA fragmetnts, sometimes a synthetic DNA called a linker is used. The linkr helps for the recogntion of sequence and effective binding between the human DNA and vector DNA ( particularly with blunt ends).
A fragment of target DNA (for human) and the vector DNA (for plasmid) produced by a specific restriction endonuclease, possing stricky ends, can be conveniently used- for the preparation of chimeric DNA. The human DNA and vector DNA with complementary sequences are annealed. The enzyme, namely DNA ligase, seals(ligates) the DNA fragments to finally produce reduce recombinant DNA.
For the ligation of two DNA fragmetnts, sometimes a synthetic DNA called a linker is used. The linkr helps for the recogntion of sequence and effective binding between the human DNA and vector DNA ( particularly with blunt ends).
Saturday 13 August 2011
Women’s Health: Cervical Smears
All women at some point in their life will have to have a cervical smear as a part of a health checkup. But do you know exactly what a cervical smear is, and how it can affect, diagnose or treat women’s ailments? Read on for more information about this common procedure.
Women’s Health: What is a Cervical Smear?
A cervical smear is a test used on women to tell if there are any changes in the health of the cervix. This is helpful to diagnose the early stages of cancer.
The cervix is located at the end of the uterus, and connects to the top of the vagina. There is a central canal that connects the vagina to the inside of the uterus, and it measures approximately 3cm square.
Women’s Health: Why Have a Cervical Smear?
The main reason to have a cervical smear is to monitor the health of the cervix, and to lower the number of women who contract cervical cancer. The smear is targeted to detect early strains of potentially cancerous cells. If caught in time, women’s health may not suffer terribly, and the growth of the cancer may not progress further. However, a cervical smear is just a screening process; it won’t detect all forms of cancer, all of the time.
Women’s Health: Who Needs a Cervical Smear?
Women who are sexually active, or who are 18 or older (whatever comes first) should take their health in their own hands and have regular cervical smears until the age of 70. A regular smear would be every three years for most women, depending on their health and the results of the last smear. Also, women who are not healthy should have annual smears, such as those with HIV. Women who have had a hysterectomy who have had abnormal pap smears in the past should get themselves checked every year by a health practitioner; there is still a risk of abnormal cell growth at the top of the vaginal canal.
Women’s Health: How is a Cervical Smear Done?
A cervical smear is only taken when women are in good health, and are not bleeding. Any blood that appears during the testing can skew the results unnecessarily.
The procedure is performed with women on their backs, and their legs held up in the air by a health practitioner or stirrups. A speculum is placed inside the vagina, so that the health practitioner can view women’s cervix closely. Then a brush-like instrument is placed over the cervix, and cells are wiped onto the brush, and then placed onto a glass slide for diagnosis.
Women’s cervical smears can be done by a health practitioner, such as a doctor or nurse. The procedure usually only takes a couple of minutes, at the most, and isn’t painful, although it may be a bit uncomfortable.
Women’s Health: What is a Cervical Smear?
A cervical smear is a test used on women to tell if there are any changes in the health of the cervix. This is helpful to diagnose the early stages of cancer.
The cervix is located at the end of the uterus, and connects to the top of the vagina. There is a central canal that connects the vagina to the inside of the uterus, and it measures approximately 3cm square.
Women’s Health: Why Have a Cervical Smear?
The main reason to have a cervical smear is to monitor the health of the cervix, and to lower the number of women who contract cervical cancer. The smear is targeted to detect early strains of potentially cancerous cells. If caught in time, women’s health may not suffer terribly, and the growth of the cancer may not progress further. However, a cervical smear is just a screening process; it won’t detect all forms of cancer, all of the time.
Women’s Health: Who Needs a Cervical Smear?
Women who are sexually active, or who are 18 or older (whatever comes first) should take their health in their own hands and have regular cervical smears until the age of 70. A regular smear would be every three years for most women, depending on their health and the results of the last smear. Also, women who are not healthy should have annual smears, such as those with HIV. Women who have had a hysterectomy who have had abnormal pap smears in the past should get themselves checked every year by a health practitioner; there is still a risk of abnormal cell growth at the top of the vaginal canal.
Women’s Health: How is a Cervical Smear Done?
A cervical smear is only taken when women are in good health, and are not bleeding. Any blood that appears during the testing can skew the results unnecessarily.
The procedure is performed with women on their backs, and their legs held up in the air by a health practitioner or stirrups. A speculum is placed inside the vagina, so that the health practitioner can view women’s cervix closely. Then a brush-like instrument is placed over the cervix, and cells are wiped onto the brush, and then placed onto a glass slide for diagnosis.
Women’s cervical smears can be done by a health practitioner, such as a doctor or nurse. The procedure usually only takes a couple of minutes, at the most, and isn’t painful, although it may be a bit uncomfortable.
Why Child Bearing Is Healthy..?
How have women specifically put themselves outside of their natural context to make themselves more susceptible to cancers?
The average mom gives birth to about two infants. Although this is an intelligent number from the standpoint of population control, it is unnatural in that by not continuing to have pregnancies and to nurse (which stops ovulations) she will ovulate an incredible 438 times during her lifetime.
On the other hand, a woman in the primitive natural setting who may not even know what causes pregnancy or how to prevent it even if they wanted to, would have started menstruating and ovulating at age twelve and would have delivered nine babies and breast-fed them over the course of her reproductive career. Breast-feeding can continue for children in a totally natural setting for up to five or more years of age. The combination of pregnancy along with breast-feeding in the premodern setting would have decreased the number of ovulations that a primitive mother would have had to about nine.
This means that today women cycle through their menstrual periods an abnormal number of times, subjecting their bodies to surges of estrogen 50 times greater than our primitive ancestors living in a natural setting.
Many cancers of women are sensitive to high levels of female hormones.
For example, breast cancer is sensitive to estrogen. In dogs, simply removing the ovaries can often prevent or halt the progress of mammary cancer. Tamoxifen in humans is used to block estrogen activity within the mammary glands and thus is believed to exert its protective effect in this way. (This pharmaceutical agent can, however, increase the risk of uterine cancer to about the same degree that the risk of breast cancer is reduced!)
The resting periods of lower estrogen levels that women experienced in the premodern setting served a protective effect to spare organs and tissues from cancer. Women who nurse for a total period of time of even as little as two years are known to have a decreased incidence of mammary cancer.
This excess ovulation hypothesis is the likely explanation for the tragic phenomenon of modern female cancers. When humans decide to flout and repudiate nature by interfering with natural biological design, disease will always be the consequence.
If the problem is a departure from nature, then the solution is a return to it. Here are some options:
1. Refer to the Wysong Optimal Health Program for guidelines on life choices that can enhance overall health and thus hormonal health
2. Emphasize fresh raw foods in the diet and avoid processed foods as much as possible.
3. Eliminate hydrogenated oils and refined sugars. Hydrogenated oils displace healthful dietary fats and have been shown to be carcinogenic, and sugars can stimulate a rise in estrogens.
4. Try to use organic foods as much as possible and avoid synthetic materials in cosmetics, at home and in the workplace to help reduce exposure to environmental estrogens.
5. Do not attempt “low fat” or “low cholesterol” fad diets that often create dependence upon processed carbohydrates and seriously reduce important natural dietary fats and essential fatty acids.
6. Increase the consumption of natural vegetable foods containing phytoestrogens which tend to counteract estrogens.
7. Avoid hormone medications if at all possible.
8. Explore natural birth control measures.
9. Nurse your babies for as long as you can.
Modern life presents many choices, freedoms and rights. Tinkering with child bearing, however, is a choice that is not without consequences. Women need to be aware and take the steps necessary to make sure the choices they make do not also bring with them the increased risk of serious modern diseases.
The average mom gives birth to about two infants. Although this is an intelligent number from the standpoint of population control, it is unnatural in that by not continuing to have pregnancies and to nurse (which stops ovulations) she will ovulate an incredible 438 times during her lifetime.
On the other hand, a woman in the primitive natural setting who may not even know what causes pregnancy or how to prevent it even if they wanted to, would have started menstruating and ovulating at age twelve and would have delivered nine babies and breast-fed them over the course of her reproductive career. Breast-feeding can continue for children in a totally natural setting for up to five or more years of age. The combination of pregnancy along with breast-feeding in the premodern setting would have decreased the number of ovulations that a primitive mother would have had to about nine.
This means that today women cycle through their menstrual periods an abnormal number of times, subjecting their bodies to surges of estrogen 50 times greater than our primitive ancestors living in a natural setting.
Many cancers of women are sensitive to high levels of female hormones.
For example, breast cancer is sensitive to estrogen. In dogs, simply removing the ovaries can often prevent or halt the progress of mammary cancer. Tamoxifen in humans is used to block estrogen activity within the mammary glands and thus is believed to exert its protective effect in this way. (This pharmaceutical agent can, however, increase the risk of uterine cancer to about the same degree that the risk of breast cancer is reduced!)
The resting periods of lower estrogen levels that women experienced in the premodern setting served a protective effect to spare organs and tissues from cancer. Women who nurse for a total period of time of even as little as two years are known to have a decreased incidence of mammary cancer.
This excess ovulation hypothesis is the likely explanation for the tragic phenomenon of modern female cancers. When humans decide to flout and repudiate nature by interfering with natural biological design, disease will always be the consequence.
If the problem is a departure from nature, then the solution is a return to it. Here are some options:
1. Refer to the Wysong Optimal Health Program for guidelines on life choices that can enhance overall health and thus hormonal health
2. Emphasize fresh raw foods in the diet and avoid processed foods as much as possible.
3. Eliminate hydrogenated oils and refined sugars. Hydrogenated oils displace healthful dietary fats and have been shown to be carcinogenic, and sugars can stimulate a rise in estrogens.
4. Try to use organic foods as much as possible and avoid synthetic materials in cosmetics, at home and in the workplace to help reduce exposure to environmental estrogens.
5. Do not attempt “low fat” or “low cholesterol” fad diets that often create dependence upon processed carbohydrates and seriously reduce important natural dietary fats and essential fatty acids.
6. Increase the consumption of natural vegetable foods containing phytoestrogens which tend to counteract estrogens.
7. Avoid hormone medications if at all possible.
8. Explore natural birth control measures.
9. Nurse your babies for as long as you can.
Modern life presents many choices, freedoms and rights. Tinkering with child bearing, however, is a choice that is not without consequences. Women need to be aware and take the steps necessary to make sure the choices they make do not also bring with them the increased risk of serious modern diseases.
AROMITIC COMPOUND
A compound containing a benzene ring. Many speciality and commodity chemical are aromatic compounds.
AIRLIFT FERMENTER
Vessel in which a bioconversion process takes place, The sparged gas is the only source of antitation. The presence of a draft tube inside a fermenter distinguishes this type of fermenter from a bubble column.
ALGA (PL. Algae)
A chorophyll-containing, photosynthetic protist, algae are unicellular or multicellular, generally aquatic and either eukaryotic or prokaryotic.
ANTIGEN
A substance usually a protein or carbohydrate which when introduced into the body of a human or higher animal, stimulates the producation of an antibody that will react specifically with it.
ANTISERUM
Blood serum containing antibodies from animals that have been inoculated with us antigen. When administered to other animals or humans, antiserum produces passive immunity.
ANTIBODY
A protein (immunoglobulin) produced by humans or higher animals in resonse to exposure to a specific antigune and characterized by specific reactivity with its complementary antigen.
ANTIBIOTIC
A specific type of chemical substance that is admisistered to fight infections, usually bacterial infections, in humans or animals. Many antibiotics are produced by using micro-organisms, other are produced synthetically.
Criseofulvin
Griseofulvin is obtained from penicillium griseofulvin. It is used in the tretment of many superficial fungaus infections of the skin and body surfaces and is also effective in the tretmnet of some sysemic (deep-seated) mycoses. The drug is administered orally.
Nystatin
The antibiotic activity of nystatin is restricted to yeasts other fungi, e.g., Candida, Aspergillus, Penicillium, and Botrytis; it is fungicidal in action. Chemically, nystatin is a polyene with an empirical formula of C46H75NO18
ANTIFUNGAL ANTIBIOTICS
Nystatin is an antifungal agent useful in the therapy of nonsystemic fungal infections. It is produced during fermentation by a strain of Streptomyces noursei. This antibiotics was discovered in 1950 by Elizabeth HaZen and Rachel Brown.
Vancomycin
Vancomycin is an antibiotic produced by Streptomyces orientalis. Its a complex chemical entity consisting of amino acids and sugars.
Vancomycin inhibits peptidoglycan synthesis by binding the D-alanyl-D-ananine group on the peptide side chain of the membrane-bound intermediates.
Vancomycin inhibits peptidoglycan synthesis by binding the D-alanyl-D-ananine group on the peptide side chain of the membrane-bound intermediates.
Friday 12 August 2011
BACITRACIN
Bacitacin is a product of bacillus subtillis and chemicllyis a polypeptide.Bacause of its toxicity to animal and human cells its not used for systemic chemotherapy. It does have application for topical treatement of infections caused by Gram-positive bacteria.
Bacitracin interferes with regeneration of the monophosphate form of bectoprenol from the pyrophosphate form.
Bacitracin interferes with regeneration of the monophosphate form of bectoprenol from the pyrophosphate form.
POLY LINKER
A fragment generated by E.coRI gererally will not link fragment created by BamJI. New DNA sequence can be created by inserting synthetic DNA Fragments between the ends that are being ligated. DNA fragments with multiple recognition sequences for restriction endonuclease. often useful later as points where additional; DNA can be insurted by cleavage and ligation are called “Polylinker”.
RESTRICATION ENDONUCLEASE
Restriction endonucleases are found in a wide range of bacterial species warener arber discovered thet their biologicals function is to recognize and cleave foreign DNA,such DNA is said to be restricted. In the host cell’s DNA, the sequence that would be recognised by the restriction endonuclease in protected from digestion by methylation of the DNA,catalysed by specific methylase. The restiction endonulclease and the corresponding methylase in a bacterium are referred to as restriction modificaton system.there are three types of restriction endonuclease, designated I,II, and III. Type I and III are Generally large multi submit complex containing both the endonuclease and methylase activities.
Type 1 :-
These RE cleave DNA at random sites that can be more than 1000 base pairs from the recognition sequences from the 5’-end of the sequence TCA located with in recognition sites .its require ATP.
Type 2 :-
Type 2 RE were first isolated by humition smith are simpler, require no ATP,and cleavage of DNA with recognition sequences itself. Only type 2 restriction endonuclease are used for restriction mapping and gene cloning in view of thier cleavage only at specific sites.
Type 3 :-
These endonuclease cleave the DNA in a about 25 base pair from the recognition sequence. It move along the DNA in a rection that require the energy Of ATP.
Type 1 :-
These RE cleave DNA at random sites that can be more than 1000 base pairs from the recognition sequences from the 5’-end of the sequence TCA located with in recognition sites .its require ATP.
Type 2 :-
Type 2 RE were first isolated by humition smith are simpler, require no ATP,and cleavage of DNA with recognition sequences itself. Only type 2 restriction endonuclease are used for restriction mapping and gene cloning in view of thier cleavage only at specific sites.
Type 3 :-
These endonuclease cleave the DNA in a about 25 base pair from the recognition sequence. It move along the DNA in a rection that require the energy Of ATP.
ENZYMES USED IN RECOMBINANT DNA TECHNOLOGY
1. Alkaline phosphatase :-
Removes phosphate gps from 5’ end of ds DNA or RNA.
2. DNA ligas :
Join DNA molecules by forming phosphodiester linkage beween DNA
segments.
3. DNA polymerase 1 :
Synthesizes DNA complentary to a DNA template.
4. Dnase 1 :
Produces singel starnded nicks in DNA.
5. Reverse tansciptase :
Synthesizes DNA from RNA.
6. Terminal Transeferase :
Addu nuclecotides to 3’-ends of DNA or RNA useful in homopholymer tailing.The Classes of enzyme lie at the center of the general appoach to generating and propagating a recombinant DNA molecule.
7. SI nuclease:
Degrade ss DNA & RNA.
Removes phosphate gps from 5’ end of ds DNA or RNA.
2. DNA ligas :
Join DNA molecules by forming phosphodiester linkage beween DNA
segments.
3. DNA polymerase 1 :
Synthesizes DNA complentary to a DNA template.
4. Dnase 1 :
Produces singel starnded nicks in DNA.
5. Reverse tansciptase :
Synthesizes DNA from RNA.
6. Terminal Transeferase :
Addu nuclecotides to 3’-ends of DNA or RNA useful in homopholymer tailing.The Classes of enzyme lie at the center of the general appoach to generating and propagating a recombinant DNA molecule.
7. SI nuclease:
Degrade ss DNA & RNA.
ISOLATION OF SPECIFIC DNA
All fragments of DNA are obtained through gene cloning. Desired fragments of DNA is obtained ad follows :-
(i) Genomic library :-
Genomic library contains all segments of DNA i.e. is contain coding and non-coding both regions of DNA,on the other hand DNA libraies consists of only coding sequences of the total genomic content.
(ii) cDNA library :-
A cDNA is a population of bacterial transferrmants or phage lysate in which each mRNA
Is islated from an organism or tissue is represented as its cDNA insertion in a plasmid o a phage vector.
cDNA library is preferred over cienomic library.
(i) Genomic library :-
Genomic library contains all segments of DNA i.e. is contain coding and non-coding both regions of DNA,on the other hand DNA libraies consists of only coding sequences of the total genomic content.
(ii) cDNA library :-
A cDNA is a population of bacterial transferrmants or phage lysate in which each mRNA
Is islated from an organism or tissue is represented as its cDNA insertion in a plasmid o a phage vector.
cDNA library is preferred over cienomic library.
DNA cloning invoves 5 general procedures
1. Cutting DNA at precise locations.
2. Joining two DNA fragments covalently.
3. Selecting a small molecule of DNA capable of self replication. Segments of DNA to be cloned can be fromed to plasmid or viral DNAs.
4. Transfer of recombinant DNA to a host cell.
5. Selection or identification of host cell that contain recombinant DNA.
RECOMBINANT DNA TECHANOLOGEY DAN CLONING
DNA cloning involves separating a specific gene or DNA sigment from lager chromosome, attaching it to a small molecule of carrier DNA, and, then replicating this modified DNA serveal times through both the increase in cell number and creation of multipul copies of cloned DNA in each cell.
Recombinant DNA is fromed bye the Joing of genes into new combination or composite DNA molecule comprising covalently linked segments from two or more sources
Recombinant DNA is fromed bye the Joing of genes into new combination or composite DNA molecule comprising covalently linked segments from two or more sources
CALLUS
A undifferentiated cluster of plant cell tha is a first step in regeneration of plants from tissue culture.
CHLOROPHYLL
The green pigment that occurs in plants and functions in photosynthesis by absorbing and utilizing the radiant energy of the sun.
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