Available online
Description
The programme describes the search for the basic mechanisms that underlie the 24 hour biological clock.
The programme describes the search for the basic mechanisms that underlie the 24 hour biological clock.
| Module code and title: | S321, Physiology of cells and organisms |
|---|---|
| Item code: | S321; 16 |
| First transmission date: | 06-10-1974 |
| Published: | 1974 |
| Rights Statement: | |
| Restrictions on use: | |
| Duration: | 00:23:54 |
| + Show more... | |
| Producer: | Roger Jones |
| Contributors: | John Brady; Norman Cohen |
| Publisher: | BBC Open University |
| Keyword(s): | Acetabularia; Biochemical mechanisms; Biological clock; Giant American Silk Moth; Sea Hare; Theoretical models |
| Footage description: | Norman Cohen introduces the programme. He mixes bromide, bromate and malonic acid to produce a simple chemical clock mechanism. He briefly explains the kinetics of this reaction. Cohen with a graph showing the reaction of glucose in yeast. The graph indicates that once the mixture becomes anaerobic the rate of glycolysis, rises and falls in a short period rhythm. Cohen then explains that these short period rhythms can still be responsible for longer period rhythms such as circadian. He demonstrates this on an audio model where 2 short frequencies are combined to produce a longer period frequency. Cohen then briefly refers to the theoretical hypothesis based on a mathematical analysis of oscillating system, by Pavilides. John Brady discusses the criteria used to choose a suitable organism for study of circadian rhythm. Shots of a gaint American Silk Moth escaping from its pupa. Commentary by Brady explains the importance of timing in its behaviour. Brady describes James Truman's experiment at Harvard on determining the location of the circadian clock mechanism. Shots of an experiment being performed on the silk moth pupa. Brady describes the results and then the drawbacks of this experiment Brady with an aquarium containing a shellless marine mollusc, the sea hare. Shots of several sea hares. Commentary explains that in this animal the turning mechanism is located in the eyes. Brady uses a large cut away model of a sea hare eye to describe experiments done to locate precisely the clock mechanism. The results of the experiments are shown on a graph. Brady takes the model apart as he talks. results are shown on a graph. Cohen with a green marina alga (acetabularia). He explains how this single cell organism is used in the study of circadian rhythm. He describes some of the early experiments done with this organism and gives the results. Cohen sums up. |
| Master spool number: | 6HT/71534 |
| Production number: | 00525_1120 |
| Videofinder number: | 1835 |
| Available to public: | no |
