Available online
Description
The programme shows how a variety of biochemical techniques and other approaches can be applied to working out where DNA can be found, what it consists of chemically, how much of it there is, what ...its constituent parts are and how its structure can be determined.
The programme shows how a variety of biochemical techniques and other approaches can be applied to working out where DNA can be found, what it consists of chemically, how much of it there is, what ...its constituent parts are and how its structure can be determined.
| Module code and title: | S101, Science: a foundation course |
|---|---|
| Item code: | S101; 24 |
| First transmission date: | 21-08-1979 |
| Published: | 1979 |
| Rights Statement: | |
| Restrictions on use: | |
| Duration: | 00:24:00 |
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| Producer: | Roger Jones |
| Contributors: | Stephen Hurry; Irene Ridge |
| Publisher: | BBC Open University |
| Subject terms: | DNA; Genetics; Molecular structure |
| Footage description: | Shots of DNA being collected on a glass rod from a beaker. Shots of models of a DNA molecule. Commentary by Stephen Hurry introduces the programme. Irene Ridge examines a simplified model of the DNA molecule and points out the sugar backbone of the chains together with the bases which link them in a helix. Ridge also points out the types of bonds which hold the molecules together. Ridge goes on to discuss the structure of the bases in DNA. She points to models of each of the four bases found in DNA as she talks. Micrographs of stained plant cells showing the DNA present. Micrograph of stained bacteria gain showing the DNA in the cell. Stephen Hurry demonstrates a method, using a homogeniser, to break cells for the removal of their DNA. Then using a hammer on a balloon as an analogue, he shows that the homogeniser is not a gentle enough method. Jim Allen, in the laboratory, demonstrates a method for separating and purifying DNA from bacterial cells. The results are shown in a test tube under ultraviolet light. Irene Ridge examines an electron micrograph of a burst bacterial cell which shows the DNA content spilled out around the cell. She points out the incredible length of a single DNA molecule. To begin to determine the chemical nature of DNA, an experiment based on breaking DNA molecules down by hydrolysis with acid is performed. The presence of deoxyribose and phosphate is indicated. A further experiment, this time by chromatography, is performed and confirms the presence of the four bases, guanine, adenine, cytosine and thymine. Stephen Hurry goes on to explain how the proportions of each of the bases can be worked out from the chromatography experiment. He points out the remarkable regularity of the proportions. Irene Ridge discusses how, from the methods demonstrated already in this programme and using in addition x-ray diffraction, biochemists were able to work out the primary structure of the DNA molecule. Shots of models of base pairs, of an x-ray diffraction photograph of DNA, and models of the DNA molecule as she talks. |
| Master spool number: | 6HT/73012 |
| Production number: | FOUS024J |
| Videofinder number: | 1199 |
| Available to public: | no |
