DNA microarray

Scientists use a tiny chip to study life.

The chip has many tiny spots on it. Each spot holds a small piece of life. These spots are like tiny magnets.

Scientists add a sample to the chip. Parts of the sample stick to the spots. They only stick if they match perfectly. This is how they find what they need.

Some spots will glow to show a match.

This helps us learn about sickness. It can also show how plants grow. It is a great way to see how tiny things work.

A DNA microarray is a tiny tool for science.

It is often called a DNA chip. This chip has many microscopic spots on a solid surface. These surfaces can be glass, plastic, or silicon. Each spot holds a specific piece of DNA. We call these tiny pieces probes.

Scientists use these probes to find a target sample. The target is a piece of DNA or RNA from a person or plant.

The chip works through a way called hybridization. This is when two DNA strands pair up. DNA strands like to stick to parts that match them. This happens because of special bonds between them.

Scientists add the target to the chip. They then wash the chip to remove any parts that do not match well. Only the strong, matching parts stay on the spots.

To see the results, scientists use bright dyes. These dyes let out light called fluorescence. A machine measures how much light each spot gives off. A bright spot means there was a lot of target material.

This helps us study many genes at once. We can use it to look for diseases or study how cells change.

A DNA microarray is a very helpful tool for scientists.

People also call it a DNA chip or a biochip. It is a solid surface made of glass, plastic, or silicon. This surface holds many tiny spots called features. Each feature has thousands of specific DNA pieces called probes.

Scientists use these chips to study many genes all at once. They can see how much a gene is working or look at different parts of a genome. This helps them understand how living things function.

The way a microarray works is through a process called hybridization.

This happens because DNA strands like to pair up with matching strands. These matching parts form bonds between them. Scientists take a target sample and add it to the chip. The target is a piece of DNA or RNA from a sample. After the target is added, the chip is washed. This washing removes any pieces that did not stick strongly. Only the strands that matched the probes will stay on the chip.

To see what happened, scientists look for a signal.

They often use targets that are labeled with fluorescent dyes. These dyes glow when a light hits them. The brightness of the glow tells scientists how much target material is there. A very bright spot means there was a lot of that specific DNA in the sample. This is called relative quantitation. Scientists compare the brightness of one spot to another to get their results.

People have been working on this technology for a long time.

The first computerized way to look at these images was published in 1981. A scientist named Patrick O. Brown is credited with inventing the microarray. He worked with others like Jonathan Pollack and Ash Alizadeh at Stanford. They used these tools to study how different cells compare to one another. This helped start new ways to look at the genome.

Microarrays are used in many parts of science today.

They can help find diseases like cancer or heart problems. Scientists also use them to check for pathogens in food. They can even study how new drugs might work. Some arrays are made by robots that print DNA using tiny pins. Other arrays are made by building the DNA directly onto the chip surface. This technology helps us learn more about the tiny building blocks of life.

A DNA microarray, often called a DNA chip or biochip, is a powerful tool for molecular biology.

It consists of a solid surface made of glass, plastic, or silicon. This surface holds a collection of microscopic DNA spots known as features. Each feature contains picomoles of a specific DNA sequence called a probe.

Scientists use these arrays to monitor the expression levels of thousands of genes at once. They can also use them to genotype multiple regions of a genome simultaneously. This technology allows researchers to see a massive amount of biological data in a single experiment.

The fundamental mechanism of a microarray is a process called hybridization.

This relies on the property of complementary nucleic acid sequences to pair with one another. When two matching strands meet, they form hydrogen bonds between their nucleotide base pairs. A high number of these complementary pairs creates a tighter, non-covalent bond between the strands. To use the chip, scientists introduce a target sample, such as cDNA or cRNA. This target is labeled with a fluorophore, silver, or chemiluminescence marker. After hybridization, the chip is washed to remove any non-specific sequences that did not bond strongly.

Only the strongly paired target strands remain attached to the probes.

Researchers detect these interactions through relative quantitation. The intensity of the signal from a single spot depends on the amount of target sample that bound to the probes. By measuring the brightness of the fluorescent labels, scientists can determine the relative abundance of specific sequences. They often compare the intensity of a feature under different conditions to see how much a gene's activity has changed. This allows for precise measurement of how cells respond to various environments or treatments.

There are two primary ways these arrays are organized and manufactured. The first is the traditional solid-phase array. This type uses a collection of orderly microscopic spots arranged on a surface. The second type is the bead array. In this version, microscopic polystyrene beads carry specific probes and different dyes.

Microarrays can also be fabricated through different production methods. Some are "spotted" arrays, where a robotic arm uses fine pins to deposit pre-synthesized DNA onto glass. Others are oligonucleotide arrays, where the short DNA sequences are synthesized directly onto the chip surface using photolithography.

Microarrays serve many specialized scientific purposes. Gene expression profiling is used to study how genes react to pathogens or different developmental stages. Comparative genomic hybridization allows scientists to assess genome content in different organisms.

Other specialized arrays include SNP arrays, which detect single nucleotide polymorphisms. These are used in forensic analysis and to identify predispositions to cardiovascular diseases or cancer. There are even tiling arrays, which use overlapping probes to represent entire genomic regions, such as a human chromosome.

The history of this technology is rooted in the push for computerized biological analysis. The first computerized image-based analysis was published in 1981. The microarray was later invented by Patrick O. Brown. He worked alongside researchers like Jonathan Pollack and Ash Alizadeh at Stanford University. Their work on comparative genomic hybridization helped establish new ways to compare the genomes of different cells. This foundation has led to the development of arrays that can now contain as many as 5 million probes.

Today, the applications of microarray technology connect to many different fields of medicine and industry. In clinical settings, they help identify structural variations and fusion genes often found in cancer specimens. In agriculture, specialized arrays are used for molecular breeding to screen seedlings. They can also be used to identify the presence of pathogens or GMOs in food and feed. By providing a way to look at the entire genetic landscape at once, microarrays continue to be essential for modern genomic research.