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Showing 1-19 of 19 Resources
  • Seeing Single Molecules Move

    Seeing Single Molecules Move

    Animations

    (1 min 40 sec) Single-molecule analysis using super-resolution microscopes reveals that transcription factors are not usually found bound to their binding sites on DNA.

  • The Double Helix

    The Double Helix

    Short Films

    (16 min 53 sec) This film tells the story of the scientists and the evidence involved in one of the most important scientific quests of the 20th century: the discovery of the structure of DNA.

  • The Chemical Structure of DNA

    The Chemical Structure of DNA

    Animations

    (2 min 44 sec) DNA's chemical properties can be harnessed for a variety of biotechnology applications.

  • Polymerase chain reaction (PCR)

    Polymerase chain reaction (PCR)

    Animations

    (54 sec) PCR is a standard laboratory technique that allows amplification of specific segments of DNA based on complementarity.

  • Triplet code

    Triplet code

    Animations

    (1 min 8 sec) Once the structure of DNA was discovered, the next challenge was determining how the sequence of letters coded for the 20 amino acids. In theory, one or two letters can only code for 4 or 16 amino acids, respectively. A scheme using three letters, a triplet code, is the minimum necessary to encode for all the amino acids.

  • DNA Transcription (Advanced Detail)

    DNA Transcription (Advanced Detail)

    Animations

    (1 min 55 sec) This animation shows how RNA polymerase and other transcription factors interact to transcribe DNA into RNA.

  • DNA Transcription (Basic Detail)

    DNA Transcription (Basic Detail)

    Animations

    (1 min 55 sec) This animation shows the transcription of DNA into RNA.

  • Sanger method of DNA sequencing

    Sanger method of DNA sequencing

    Animations

    (52 sec) 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 strands are ordered by size, and by reading the end letters from the shortest to the longest piece, the whole sequence of the original DNA is revealed.

  • DNA Replication (Advanced Detail)

    DNA Replication (Advanced Detail)

    Animations

    (2 min 20 sec) This animation shows the process of DNA replication, including details about how the mechanism differs between the leading and lagging strand.

  • DNA replication (basic detail)

    DNA replication (basic detail)

    Animations

    (1 min 7 sec) Using information from molecular research, this 3-D animation shows how DNA is replicated at the molecular level. It involves an enzyme that unwinds the DNA, and other enzymes that copy the two resulting strands. Also available in Spanish.

  • DNA Replication (Schematic)

    DNA Replication (Schematic)

    Animations

    (50 sec) This animation shows a schematic representation of the mechanism of DNA replication.

  • Polymerase chain reaction

    Polymerase chain reaction

    Animations

    (1 min 28 sec) Polymerase chain reaction, or PCR, is a technique for making many copies of a specific DNA sequence. DNA is repeatedly heated and cooled in the presence of primers that bracket the desired sequence and of the enzyme Tac polymerase. In as few as 30 cycles, a billion copies of the target sequence can be made.

  • Paired DNA strands

    Paired DNA strands

    Animations

    (1 min 18 sec) DNA has a double helix structure. If untwisted, DNA looks like two parallel strands. Each strand has a linear sequence of A, C, G, and T. The precise order of the letters carries the coded instructions. One strand is a complementary image of the other: A always pairs with T, and C always pairs with G.

  • DNA packaging

    DNA packaging

    Animations

    (1 min 44 sec) DNA is tightly packed in the nucleus of every cell. DNA wraps around special proteins called histones, which form loops of DNA called nucleosomes. These nucleosomes coil and stack together to form fibers called chromatin. Chromatin in turn forms larger loops and coils to form chromosomes.

  • Damage to DNA leads to mutation

    Damage to DNA leads to mutation

    Animations

    (1 min 7 sec) 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.

  • Coding sequences in DNA

    Coding sequences in DNA

    Animations

    (1 min 5 sec) Of the 3 billion letters in the human genome, only 1% directly code for proteins. Of the rest, about 25% make up genes and their regulatory elements. The functions of the remaining letters are still unclear.

  • Chargaff's Ratio

    Chargaff's Ratio

    Animations

    (49 sec) In 1950, Erwin Chargaff published a paper stating that in the DNA of any given species, the ratio of adenine to thymine is equal, as is the ratio of cytosine to guanine. This became known as Chargaff's ratio, and it was an important clue for solving the structure of DNA.

  • Building blocks of DNA

    Building blocks of DNA

    Animations

    (27 sec) Adenine (A), cytosine (C), guanine (G), and thymine (T) are the components of nucleic acid that make up DNA.

  • Mismatch Repair

    Mismatch Repair

    Animations

    (1 min 22 sec) This animation illustrates how mistakes made during DNA replication are repaired.