Circadian Rhythms

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Circadian Rhythms: Keeping Time

Circadian rhythms
are found in most living things, including plants, animals and many microorganisms. These rhythms are the repeating patterns that we see in the biochemical, physiological, and behavioural processes. The rhythms follow a roughly 24-hour cycle linked to the patterns of light and dark in the environment around the organism. Humans are no exception, with processes and behaviours such as sleep, cell division, and alertness following this 24-hour cycle.

This Circadian Rythms: Keeping Time Seminar includes these resources to assist your learning :

The Seminar Paper and Questions

Download the Circadian Rhythms Seminar Paper paper and read this in preparation for your seminar.

Use the focus questions in the Circadian Rhythms Pre-Seminar Discussion Paper to help you as you read the seminar paper.

The Circadian Rhythms Challenge Questions below are for discussion in your school workshop after the seminar: 

1. The period of most circadian rhythms is not exactly 24 hours. Explain the need for the entrainment of circadian rhythms and the role of environmental cues in this process. Answer this question here.

2. Changes in our daily rhythms such as those caused by Jet Lag and Daylight Saving affect most people but are particularly difficult for teenagers.
(i) Explain why people are affected by the change in time that occurs when daylight saving starts and finishes and why this is particularly difficult for teenagers.
(ii) Which end of daylight saving (April when we put the clocks back an hour, or October when we put the clocks forward an hour) is more likely to have a negative effect on teenagers and why?
(iii) Use your knowledge of human circadian rhythms and evidence from the seminar to explain the quickest way for someone to adjust to the new time at the start and end of daylight saving.

Answer this question here.

3. Using your knowledge of the ability of the bee to use the sun as a compass, discuss the differences seen in the results from the different treatments and predict the results of further treatments carried out using different durations of anaesthesia.

Answer this question here.

4. Figure 7 (page 8 of the seminar paper) shows the levels of mRNA expression from the clock gene cryptochrome. Use your knowledge of gene expression and the regulation of gene expression to discuss how clock genes can act as a biological clock.

Answer this question here.

This page will be monitored by teachers and scientists who will respond to your discussion.

The Seminar Multi-Media

A copy of the seminar Powerpoint is available  here and you can download a copy of seminar video here. Or watch it now below.

About the Presenters

Guy Warman | Michal Denny

Chronobiology Research at The University of Auckland

Dr Guy Warman leads the Chronobiology Research Group at The University of Auckland. A range of chronobiology research is conducted at the university with interdisciplinary projects between the Faculty of Medical and Health Sciences and the School of Biological Sciences. Projects include molecular and behavioural chronobiology in both animals and plants, and applied research on human chronobiology and chronopharmacology. 

Chronobiology is taught at the undergraduate (Animal Behaviour BIOSCI337) and post-graduate level. 

For more information on some of the current research projects see Chronobiology Research - Projects

Links to your school programme

This seminar links to the following NCEA Level 3 Achievement Standards:

  • AS 90716 Describe animal behaviour and plant responses in relation to environmental factors
  • AS 90715 Describe the role of DNA in relation to gene expression
  • AS 90718 Describe applications of biotechnological techniques

A list of objectives from your Year 13 programme that link into the seminar can be found on page 2 of the Pre-Seminar Questions and Discussion.

Useful Resources for this Seminar

Circadian Rhythms


Teenagers and Sleep

Biological Clocks

Scientific Papers available online

Connections between Circadian Rhythms and previous LENScience seminars