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Gel electrophoresis

In the early days of DNA manipulation, DNA fragments were laboriously separated by gravity. In the 1970s, the powerful tool of DNA gel electrophoresis was developed. This process uses electricity to separate DNA fragments by size as they migrate through a gel matrix. Gel electrophoresis can be used to...

Polymerase chain reaction (PCR)

Polymerase chain reaction (PCR) enables researchers to produce millions of copies of a specific DNA sequence in approximately two hours. This automated process bypasses the need to use bacteria for amplifying DNA.

This resource is part of the ...

Human genome sequencing

The public Human Genome Project started by identifying unique marker sequences distributed throughout the genome. Then, many copies of a small section of DNA were randomly cleaved into smaller fragments, and each small fragment was sequenced. Because there were originally many copies of the DNA in question, many...

Sanger method of DNA sequencing

Fred Sanger developed the first technique for sequencing DNA. DNA is replicated in the presence of chemically altered versions of the A, C, G, and T bases. These bases stop the replication process when they are incorporated into the growing strand of DNA, resulting in varying lengths of short DNA. These short DNA...

Making and running an agarose gel

A video guide for students illustrating the processes involved in running agarose gels in the laboratory.


Preparing the gel

Pouring the gel

Putting the gel into the gel tanks

Loading the samples

Running the gel

Visualising the nucleic acids...

DNA sequencing - the Sanger method

In this method, the DNA is used as a template to generate a set of fragments that differ in length from each other by a single base. The fragments are then separated by size, and the bases at the end are identified, recreating the original sequence of the DNA.

This resource is part of the ...

Evolution of the Y chromosome

How did the human Y chromosome become so small relative to its X counterpart? This animation depicts the 300-million-year odyssey of the sex chromosomes that began when the proto X and Y were an identical pair.

Used with permission from the Howard Hughes Medical Institute, Copyright (2001).  All rights...

Damage to DNA leads to mutation

Reactive molecules, such as free radicals, and solar ultraviolet radiation can lead to mutations in DNA. Most mutations are corrected, but in rare cases mutations can accumulate and cause diseases such as cancer.

Used with permission from the Howard Hughes Medical Institute, Copyright (2003).  All rights...

Mismatch repair

This animation illustrates how mistakes made during DNA replication are repaired. 

During DNA replication mistakes can occur as DNA polymerase copies the two strands. The wrong nucleotide can be incorporated into one of the strands causing a mismatch. Normally there should be an "A" opposite a "T" and "G"...

Human genomics: a new guide for medicine

Dr. Lander explores human genetic variation and how it may affect individual susceptibility to certain diseases. With the exception of identical twins, no two human genomes are exactly the same. But how different are they? Are two humans more alike than two orangutans? Dr. Lander explores human genetic variation...


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