DNA probe

DNA probe

DNA probes are small segments of DNA which help to detect the presence of a gene of a long DNA sequence, in a biological systems. These DNA probes are prepared for commercial purposes and are believed to be the most sophisticated and sensitive means to identify genes or specific DNA sequences. DNA probes provide commercial avenues for diagnosis of infection diseases, identification of food contaminants for isolation of genes and in other microbiological tests.

It is believed that, these DNA probe assays for variety of purposes will be cleaner, simpler, faster and cheaper than the traditional microbiological tests and are also expected to be hundred fold more sensitive.

The production of DNA probes can be done by any of the following methods. Such as
a) using a template DNA with the help of purified biological enzymes 
b) DNA probe of specific sequence can also be obtained by using automated DNA synthesizers 
c) DNA probe can also be included in viral DNA and may even multiply in bacteria, thus by this way many copies of DNA probe can be obtained.
However, the DNA probe assay consists of the following steps. 
Sample to be tested is treated with detergents and enzymes to remove non DNA components. Then DNA is denatured by low PH. 
Single stranded DNA binds on filters and is exposed to excess of DNA probes but only one of which will hybridize.
At the same time unbound DNA is detected by a variety of available methods using florescence and dye etc

Retinoblastoma

Retinoblastoma - (Reh-tin-oh-blast-oma)

• Retinoblastoma is a rare, cancerous tumor of a part of the eye called the retina

• Retinoblastoma - (Reh-tin-oh-blast-oma) is a cancer of one or both eyes which occurs in young children. There are approximately 350 new diagnosed cases per year in the United States. Retinoblastoma affects one in every 15,000 to 30,000 live babies that are born in the United States. Retinoblastoma affects children of all races and both boys and girls
• The retinoblastoma tumor(s) originate in the retina, the light sensitive layer of the eye which enables the eye to see. When the tumors are present in one eye, it is referred to as unilateral retinoblastoma, and when it occurs in both eyes it is referred to as bilateral retinoblastoma. Most cases (75%) involve only one eye (unilateral); the rest (25%) affect both eyes (bilateral). The majority (90%) of retinoblastoma patients have no family history of the disease; only a small percentage of newly diagnosed patients have other family members with retinoblastoma (10%).

 

• The eye of an adult measures about one inch from the front to the back of the eye; a child's eye measures about three-quarters of one inch.

• The eye has three layers:

1. Sclera - the outer protective white coating of the eye

2. Choroid - the middle layer which contains blood vessels to nourish the eye

3. Retina - the inner layer which contains the nerves that bring information to the brain for     seeing

• The cornea is the clear portion of the front of the eye which bends light rays. 
• The conjunctiva is a thin tissue which lines the eyelids and the eyeball up to the edge of the cornea. 
• The iris is the colored portion of the eye which is made up of a spongy tissue and is an extension of the choroid. 
• The pupil is the opening in the iris (black) which allows light into the eye.
• The lens helps focus light rays onto the retina the way a camera lens focuses light onto film; the lens can change shape, or accommodate, to focus on near or distant objects.
• The eye is filled with fluids which help nourish and maintain the pressure within the eye. The anterior chamber, the front portion of the eye between the iris and the cornea, is filled with aqueous humor, a watery fluid which nourishes the lens and mantains the pressure within the eye. 
• The back portion of the eye is filled with vitreous humor, a transparent gel.
• The retina is made up of ten layers and contains over one million cells.
• The optic nerve has nerve fibers which transmit information to the brain for interpretation of objects seen.
• The macula is the area of the retina that is responsible for central vision; its central portion is referred to as the fovea and is responsible for the sharpest vision.
• The macula houses the highest concentration of the cones which are responsible for color and sharp vision. 
• The rods, which compose the rest of the retina, are more sensitive to light and are responsible for night vision and peripheral vision. 
• Attached to the globe of the eye are six muscles which aid in the movement of the eye. Movement of the eye may be caused by one, a few, or all of the muscles working together. 
• Causes, incidence, and risk factors 
• Retinoblastoma is caused by a mutation in a gene controlling cell division, causing cells to grow out of control and become cancerous.
• In a little over half of the cases, this mutation develops in a child whose family has never had eye cancer.
• Other times the mutation is present in several family members. If the mutation runs in the family, there is a 50% chance that an affected person's children will also have the mutation. They will therefore have a high risk of developing retinoblastoma themselves.
• The cancer generally affects children under the age of 6. It is most commonly diagnosed in children aged 1 - 2 years.
  Symptoms 
• One or both eyes may be affected.
• The pupil may appear white or have white spots. 
• A white glow in the eye is often seen in photographs taken with a flash. Instead of the typical "red eye" from the flash, the pupil may appear white or distorted.
• Other symptoms can include
• Crossed eyes
• Double vision
• Eyes that do not align
• Eye pain and redness
• Poor vision
• Differing iris colors in each eye
• If the cancer has spread, bone pain and other symptoms may occur.
  Signs and testsThe health care provider will perform a complete physical exam, including an eye exam. The following tests may be done:
• Bone marrow biopsy and cerebrospinal fluid examination in the case of more aggressive tumors
• CT scan or MRI of the head
• Eye exam with dilation of the pupil
• Ultrasound of the eye (head and eye echoencephalogram)
  
  Treatment 
• Treatment options depend on the size and location of the tumor.
• Small tumors may be treated by laser surgery or cryotherapy.
• Radiation is used for both local tumor and for larger tumors.
• Chemotherapy may be needed if the tumor has spread beyond the eye.
• The eye may need to be removed (a procedure called enucleation) if the tumor does not respond to other treatments. In some cases, it may be the first treatment.
  Expectations (prognosis) 
• If the cancer has not spread beyond the eye, almost all patients can be cured. A cure, however, may require aggressive treatment and even removal of the eye in order to be successful.
• If the cancer has spread beyond the eye, the likelihood of a cure is lower and depends on how the tumor has spread.
  Complications
  Blindness can occur in the affected eye. The tumor can spread to the eye socket through the optic nerve. It may also spread to the brain, lungs, and bones.
  Prevention
  Genetic counseling can help families understand the risk of retinoblastoma. It is especially important when more than one family member has had the disease, or if the retinoblastoma occurs in both eyes.
• sources : http://www.ncbi.nlm.nih.gov/pubmedhealth/PMH0002025/
• sources : http://retinoblastoma.com/retinoblastoma/frameset1.htm

Plant Tissue Culture

Plant Tissue Culture

The process by which desirable plants can be grown from any plants part,tissue or cells artificially in the laboratory in an artificially prepared nutrient medium under aseptic condition is known as plant tissue culture.

Historical background of tissue culture:

Haberlandt(1896) was the first person to culture isolated vegetative cells.He was able to maintain the cell in the medium but failed to differentiate it.In 1934 different worker P.R. white,R.s Gautherate and P.Hobegurt were able to grow cambium cells from tobacco stem and carrot root on artificial culture medium.However,this culture failed to differentiate and grew as undifferentiated masses of parenchymatous cells called callus which could be propagated indifinitely by repeated subculturing on fresh culture medium.

Equipments used for Tissue culture:

To get success in vitro culture or micropropagation a laboratory should have following equipments and facilites.They are:
i)pH meter

 ii)Chemical balance 

iii)Hot air oven 

iv)Centrifuge 

v)Auto clave 

vi)UV lamp 

vii)Shaker
viii)Dissecting microscope

 ix)Compound microscope 

x)Refrigerator 

xi)Laminar air flow cabinet 

xii)Essential glass

Methods of Plant Tissue Culture:

a)Nutrient Medium:
Cultured tissue can not synthesize their own food and need an external supply i.e they are heterotroph.The medium or cultured medium used in tissue culture is basal medium.It include following things:
i) Inorganic Nutrients:
It includes all the 16 elements which are essential for normal and healthy life of plants.These elements can be grouped into Macro and micro elements.
 

Macro elements: C,H,O,P,K,Ca,S,Mg
Micro elements :Zn,Fe,Cu,B,Mn,Mo and Cl
ii)Organic elements :
 

It includes sucrose,glucose,fructose,carbohydrats and vitamins.
 

iii)Natural extracts:
natural extract like yeast extract,coconut milk,tomato juice,malt extract are added in the medium.
iv)Growth Hormone:
it includes auxin,cytokinin and gibberellin
Some of the standard media available are Murasbige and Skoog's media,White's media and Nitschs media.
v)Agar:
Agar is a polysaccharide substance obtained from sea weeds which is used to provide solid surface for growth.

b)Sterilization or Aseptic Condition:
The culture must be totally free from microbian contamination.Microbes may enter culture through the ingredients of medium,througn plant organ or explant and through air so that the culture vessel and instrumenti.e glasswares,metal instruments are sterilized by exposure to hot dry air at 160 C to 170 C for 2-4 hours in a hot air oven.
i)Culture Medium:
Culture vessels containing the medium are plugged and autoclaved at 120 C for about 15-20 minutes.
ii)Plant material or Explant:
Plant material or explants are surfacesterilized by using sodium hypochloride or calcium hypochloride solution.After surfacesterilization plant materials are washed 3-4 times in a sterile distill water.
iii)Transfer Arae:
Inoculation is carried out in a laminar air flow cabinet.In this cabinet filterate sterile air flows inside at a constant rate.The flow is unidirectional and makes the cabinet sterile.
To avoid contamination hands and arms are washed with soap and then 95% ethanol.Thus an aseptic environment is maintained for tissue inoculation.

c)Light:
Normally it is not necessary for growth of culture but it plays an important role in inducing differentiation.The intensity and duration of illumination varies from species to species.

d)Temprature:
Generally 25 to 27 degree centigrade is necessary for callus growth.

e)Humidity:
A relative humidity of 70-75% is optimum for the growth of culture.

Types of plant Tissue Culture:

Plants material used for plant tissue culture is known as explants.On the basis of explants used for plant tissue culture,it is of following type:
a)Shoot Culture:
Plant tissue culture in which sterile shoot tips or axillary buds are used as explants is called Shoot culture.

b)Protoplast Culture:
Here,protoplast is used as culture.Somatic hybrid can be produced from protoplast culture.

c)Embryo Culture:
The plant tissue culture in which embroyo is used as explant is known as embryo culture.

d)Anther Culture :
The plant tissue culture in which anther is used as explant is known as Anther culture.By this haploid plant is produced which is of great importance to scientist as mutation can be induced in them.

e) Meristem Culture:
The plant tissue culture in which apical meristem is taken as explant is known as meristem culture.Through this disease resistance plant can be produced.

Applications of Plant Tissue Culture:

1)Micro propagation:
Rapid asexual or vegetative propagation of plant in vitro is called micro propagation.Large no of plants can be produced throughout the year.

2)Somatic Hybridization:
Fusion of somatic cells in vitro is called somatic hybridisation.Novel hybrid can be produced in sexually incompatible species.

3)Production of Haploid Plants:
Through anther culture haploid plants are produced.It is very important in research point of view as mutation can be induced and detected.

4)Production of Pathogen Free Plants:
Through meristem culture,virus free plants can be produced from diseasesd material.

5)Production of Disease Resistant Varieties:
Many plants are dying due to presence of virus or bacteria.So,plant tissue culture has been able to produce disease resistance variety of plants.

6)Minimize the using space:
Tissue culture can be used to minimize the growing space in commercial nurseries for maintenance of stock plants. 
Souce: http://technologysifi.blogspot.in/2010/03/plant-tissue-culture.html

Terms commonly used in Genetics

Terms commonly used in Genetics

Base pairs:

A set of two bonded nucleotides on opposite strands of DNA. There are two possible base pairs: C-G and A-T.

Chromosome:

A rod-like structure of tightly coiled DNA found in the cell nucleus of plants and animals. Chromosomes are normally found in pairs; human beings typically have 23 pairs of chromosomes.

DNA polymerase:

An enzyme which repairs DNA by facilitating the formation of hydrogen bond between a nucleotide on a broken piece of DNA, such as a nicked or single-stranded piece of DNA as created in the laboratory, and the individual nucleotide it needs to form a complete and stable base pair.

Gene:

A section of a chromosome, made up of DNA. A given gene provides the information a cell needs to create a specific protein. Collectively, the genes of an organism inform, to some extent, nearly every aspect of the development and formation of that organism. Genes do not, however, dictate behaviors or traits, and neither are genetically informed behaviors and traits incapable of being modified or supplanted; environmental factors also play a very important part in influencing the organism's development and formation.

Homology:

The degree to which two pieces of DNA match, or complement each other (two pieces of DNA are complementary if their respective nucleotides, in their current order, match C to G and A to T). If one piece of DNA is 100% complementary to another piece of DNA, they demonstrate very high homology; if the pieces are only able to form a handful of base pairs between their corresponding nucleotides, they demonstrate very low homology.

Hybridization Reaction:

A process in which a probe binds to a Southern Blot if the probe's DNA sequence and the DNA on the Southern Blot match.

Nucleus:

The center of a cell, where all of the DNA, packaged in chromosomes, is contained.

Probe:

A radioactive strand of DNA often used to find particular sequences in a Southern Blot.

Restriction enzyme:

An enzyme normally found in bacteria which cuts DNA at specific sites (i.e. each time a specific nucleotide pattern occurs). Because a restriction enzyme always acts upon DNA in the same manner, a map can be made of a restriction enzymes actions on a known set of nucleotides.

Trait:

The physical manifestation of the information on a gene. If a gene contains the information needed by the organism to create purple eyes, for example, the fact that the organism did indeed have purple eyes is considered a trait of that organism.

 Allele: 

allele is an alternative form of gene.

Applications of DNA Fingerprinting

 Applications of DNA Fingerprinting

1. Paternity and Maternity

Because a person inherits his or her VNTRs from his or her parents, VNTR patterns can be used to establish paternity and maternity. The patterns are so specific that a parental VNTR pattern can be reconstructed even if only the children's VNTR patterns are known (the more children produced, the more reliable the reconstruction). Parent-child VNTR pattern analysis has been used to solve standard father-identification cases as well as more complicated cases of confirming legal nationality and, in instances of adoption, biological parenthood.

2. Criminal Identification and Forensics

DNA isolated from blood, hair, skin cells, or other genetic evidence left at the scene of a crime can be compared, through VNTR patterns, with the DNA of a criminal suspect to determine guilt or innocence. VNTR patterns are also useful in establishing the identity of a homicide victim, either from DNA found as evidence or from the body itself.

3. Personal Identification

The notion of using DNA fingerprints as a sort of genetic bar code to identify individuals has been discussed, but this is not likely to happen anytime in the foreseeable future. The technology required to isolate, keep on file, and then analyze millions of very specified VNTR patterns is both expensive and impractical. Social security numbers, picture ID, and other more mundane methods are much more likely to remain the prevalent ways to establish personal identification.

sources: http://protist.biology.washington.edu/fingerprint/apps.html

What Is Bt Cotton?

What Is Bt(Bacillus thuringiensis) Cotton?

Bt Cotton is a genetically modified cotton crop that has one or two genes of a soil bacterium inserted into the seeds of cotton.

History

 Bt Cotton seeds were introduced by Bollgard Cotton, a trademark of the Monsanto group. Bt Cotton was first introduced to the U.S. in 1996 according to the University of California San Diego and was aimed at reducing the effects of the tobacco budworm and the pink bollworm. Tests began at the same time around the world on crossing the American Bt Cotton seeds with cotton produced in other countries, including India, according to the Science & Development Network. Later versions of Bt Cotton were introduced in 2003 and 2004 aimed at reducing the impact of a wider range of insects than the original version.

Bacterium

 The University of California San Diego describes Bt Cotton as containing a bacterium called Bacillus Thuringiensis (Bt). The spores of Bt produce crystal proteins which are toxic to many forms of insects, leading to its use as an insecticide. The University of California San Diego reports Bt is found throughout the world in a variety of soils in very small amounts producing thousands of different strains of Bt. The University of California San Diego reports Bt does not produce food poisoning proteins, Despite being a member of the food poisoning Bacillus Cerus family of bacterium; Bt Cotton has a very small chance of cross contamination due to its lack of use in food production.

Benefits

 The benefits provided by Bt Cotton are explained by the University of California San Diego as including a reduced cost per acre of between $25 and $65 in the years of 1996 to 1998 from the spraying of insecticides. Bt Cotton crops are estimated by the University of California San Diego to have yielded around 5% more cotton than traditionally grown cotton crops planted during the same time period.

Problems

According to the Science and Development Network, Bt Cotton crops in India are being affected by the bollworm that is becoming resistant to the Bt toxins and proteins produced by Bt Cotton. Bt Cotton is one of the 21 genetically modified crops introduced to 21 countries around the world by 2006. Four of the 21 crops are reported by the Science and Development Network to have been affected by insects resistant to the insecticides initially introduced to the crops.

Insecticide

The insecticide introduced to each version of Bt Cotton is reported by the University of California San Diego to be created to be specific to the insect at which it is aimed. The use of Bt Cotton as an organic form of insecticide is commonly used in organic farming and in aerial spraying of urban areas.
Sources:http://www.ehow.com/about_6372845_bt-cotton_.html

What Is the Bt(Bacillus thuringiensis) Gene?

 What Is the Bt(Bacillus thuringiensis) Gene?

Bacillus thuringiensis, or Bt, is a type of bacterium found in soil. Bt bacteria produce protein crystals known to be toxic to several varieties of insect larvae, including moths, beetles, mosquitoes, black flies, nematodes and flatworms. The Bt gene is a small stretch of DNA from the Bt chromosome that codes for the production of these protein crystals. Davidson College states that both Bt bacteria and the Bt gene products are used as insecticides in the U.S., Canada, Argentina, South Africa and parts of Europe.

History:

 Bt bacteria were discovered in 1901 in Japan, and were brought to the U.S. in 1958 for agricultural use. Initially, the bacteria were grown and harvested to be used as crop sprays and dusts, according to Davidson College. As the field of genetic engineering evolved and the Bt gene was identified and isolated, it became one of the first genes to be inserted directly into the hereditary structure or genome of plant crops, creating genetically modified Bt crops. In doing so, the plants themselves were able to produce the toxic protein crystals and thus become resistant to Bt affected insects without the need for spraying.

Uses:

Today the Bt gene has been incorporated into a variety of cash crops grown and sold around the globe, including corn, potatoes, broccoli, cauliflower, cotton and tobacco. Whole Bt bacteria are still dusted in U.S. forests to control spruce budworms and gypsy moths, according to Iowa State University. Bt is also used in common household insecticide sprays intended for garden use.

Benefits:

Bt is washed away from plants with water or rain, and it is broken down by sunlight. These properties convey an environmental benefit. However, as the Bt must be eaten by insects to be effective, this trait makes Bt a less potent insecticide than some synthetics which kill on contact. By genetically engineering crops to contain the Bt gene and be constantly producing their own Bt toxin, the plant will be insect resistant regardless of weather patterns. Bt crops can also kill insects even after they have invaded the plant tissues, as reported by Iowa State University.

Safety

Both Bt crops and commercially produced Bt insecticides are classified as "Generally Regarded as Safe" (GRAS) by the Environmental Protection Agency. The protein crystal which is toxic to insects is safe for human consumption, as humans lack the digestive enzyme required to convert the protein to its toxic form, according to Davidson College. Studies of Bt's effects on animals have produced contradictory results, and it is lethal to Monarch butterflies.

Considerations

One cost of producing Bt crops is that insect resistance will still occur, likely at a higher rate than it would in non-Bt crops. Bt will kill most of a given species of insect, but never all of them. Of those that survive, a high percentage of them will be naturally Bt resistant, becoming the parents of future generations. A second issue with genetically modified crops involves gene flow, the unintentional transfer of genes from one plant species to another, according to Davidson College. This may occur through pollination of Bt crops grown in close geographic proximity to other crops, thereby introducing Bt genes into other plants.
  
Source:http://www.ehow.com/about_7238414_bt-gene_.html

Procedure For DNA Fingerprinting

Procedure for DNA fingerprinting involves following steps:

    1. Performing a Southern Blot
     2. Making a Radioactive Probe
     3. Creating a Hybridization Reaction
     4. VNTRs 

• Southern Blot

  The Southern Blot is one way to analyze the genetic patterns which appear in a person's DNA. Performing a Southern Blot involves:
  
  1. Isolating the DNA in question from the rest of the cellular material in the nucleus. This can be done either chemically, by using a detergent to wash the extra material from the DNA,or mechanically, by applying a large amount of pressure in order to "squeeze out" the DNA.
  
  2. Cutting the DNA into several pieces of different sizes. This is done using one or more restriction enzymes.
  
  3. Sorting the DNA pieces by size. The process by which the size separation, "size fractionation," is done is called gel electrophoresis. The DNA is poured into a gel, such as agarose, and an electrical charge is applied to the gel, with the positive charge at the bottom and the negative charge at the top. Because DNA has a slightly negative charge, the pieces of DNA will be attracted towards the bottom of the gel; the smaller pieces, however, will be able to move more quickly and thus further towards the bottom than the larger pieces. The different-sized pieces of DNA will therefore be separated by size, with the smaller pieces towards the bottom and the larger pieces towards the top.
  
  4. Denaturing the DNA, so that all of the DNA is rendered single-stranded. This can be done either by heating or chemically treating the DNA in the gel.
  
  5. Blotting the DNA. The gel with the size-fractionated DNA is applied to a sheet of nitrocellulose paper, and then baked to permanently attach the DNA to the sheet. The Southern Blot is now ready to be analyzed.
  
  
  In order to analyze a Southern Blot, a radioactive genetic probe is used in a hybridization reaction with the DNA in question (see next topics for more information). If an X-ray is taken of the Southern Blot after a radioactive probe has been allowed to bond with the denatured DNA on the paper, only the areas where the radioactive probe binds [red] will show up on the film. This allows researchers to identify, in a particular person's DNA, the occurrence and frequency of the particular genetic pattern contained in the probe. 
  
  

   Making a Radioactive Probe  

  1.Obtain some DNA polymerase [pink]. Put the DNA to be made radioactive (radiolabeled) into a tube.
        
  2.Introduce nicks, or horizontal breaks along a strand, into the DNA you want to radiolabel. At the same time, add individual nucleotides to the nicked DNA, one of which,*C [light blue], is radioactive. 
   
  3.Add the DNA polymerase [pink] to the tube with the nicked DNA and the individual nucleotides. The DNA polymerase will become immediately attracted to the nicks in the DNA and attempt to repair the DNA, starting from the 5' end and moving toward the 3' end. 
   
  4.The DNA polymerase [pink] begins repairing the nicked DNA. It destroys all the existing bonds in front of it and places the new nucleotides, gathered from the individual nucleotides mixed in the tube, behind it. Whenever a G base is read in the lower strand, a radioactive *C [light blue] base is placed in the new strand. In this fashion, the nicked strand, as it is repaired by the DNA polymerase, is made radioactive by the inclusion of radioactive *C bases.  
     
  5.The nicked DNA is then heated, splitting the two strands of DNA apart. This creates single-stranded radioactive and non-radioactive pieces. The radioactive DNA, now called a probe [light blue], is ready for use.
  
  
  

  • Creating a Hybridization Reaction

     
    Creating a Hybridization Reaction
    
    1. Hybridization is the coming together, or binding, of two genetic sequences. The binding occurs because of the hydrogen bonds [pink] between base pairs. Between a A base and a T base, there are two hydrogen bonds; between a C base and a G base, there are three hydrogen bonds.
    
    
    2. When making use of hybridization in the laboratory, DNA must first be denatured, usually by using heat or chemicals. Denaturing is a process by which the hydrogen bonds of the original double-stranded DNA are broken, leaving a single strand of DNA whose bases are available for hydrogen bonding.
    
    
    3. Once the DNA has been denatured, a single-stranded radioactive probe [light blue] can be used to see if the denatured DNA contains a sequence similar to that on the probe. The denatured DNA is put into a plastic bag along with the probe and some saline liquid; the bag is then shaken to allow sloshing. If the probe finds a fit, it will bind to the DNA.
     
    4. The fit of the probe to the DNA does not have to be exact. Sequences of varying homology can stick to the DNA even if the fit is poor; the poorer the fit, the fewer the hydrogen bonds between the probe [light blue] and the denatured DNA. The ability of low-homology probes to still bind to DNA can be manipulated through varying the temperature of the hybridization reaction environment, or by varying the amount of salt in the sloshing mixture.
    
    
    

    • VNTRs(Variable Number Tandem Repeats)

      
      
      • Every strand of DNA has pieces that contain genetic information which informs an organism's development (exons) and pieces that, apparently, supply no relevant genetic information at all (introns). Although the introns may seem useless, it has been found that they contain repeated sequences of base pairs. These sequences, called Variable Number Tandem Repeats (VNTRs), can contain anywhere from twenty to one hundred base pairs.
      
      
      • Every human being has some VNTRs. To determine if a person has a particular VNTR, a Southern Blot is performed, and then the Southern Blot is probed, through a hybridization reaction, with a radioactive version of the VNTR in question. The pattern which results from this process is what is often referred to as a DNA fingerprint.
      • A given person's VNTRs come from the genetic information donated by his or her parents; he or she could have VNTRs inherited from his or her mother or father, or a combination, but never a VNTR either of his or her parents do not have. Shown below are the VNTR patterns for Mrs. Nguyen [blue], Mr. Nguyen [yellow], and their four children: D1 (the Nguyens' biological daughter), D2 (Mr. Nguyen's step-daughter, child of Mrs. Nguyen and her former husband [red]), S1 (the Nguyens' biological son), and S2 (the Nguyens' adopted son, not biologically related [his parents are light and dark green]).
      
      
      • Because VNTR patterns are inherited genetically, a given person's VNTR pattern is more or less unique. The more VNTR probes used to analyze a person's VNTR pattern, the more distinctive and individualized that pattern, or DNA fingerprint, will be. 
      Source:http://protist.biology.washington.edu/fingerprint/dnaintro.html