Lecture 1 Flashcards
Why is light a good clock source
Day night signal is very reliable and does change year to year unlike temperature
How much of the genome changes seasonally in humans
1/3
What axis is the planet tilted by
23.5
In 1940 in trinidad, what did they show
Mosquitotes would ecolse at the most moist time of day, 3.3 hours after sunrise, inorder for their wings to unfold
What is the principle entraining signal in humans
Light
What is the clock system compensated to
Temperature, as reaction rate doubles with increase in 10oC
What are good animals to measrue clocks on
Hamsters on running wheels
Basic clock experiemnt
Entrained on a light dark cycle to 24hrs
then left to free run in constant darkness, see when they get up
In the light dar diagram, what symbols are 24hrs LD and free running periods donoted by
T
t
What is the equation to work out the phase shift
t-T = delta phi (circle with line through)
What is parametric entrainment
Light sets the clock by continually changing its speed
What is non - parametric entrainment
Light sets the clock by causing it to jump to a new phase. A short exposure should be able to set the clock
What experiment is pittendrigh do
Gave pulses to animals in the dark at different times of day and saw how this shifted the rhythm of the clock. Plotted a phase response curve which shows phase change vs time
How does a mouse entrain
Mouse with short clock will wake up earlier each evening until they get hit by pulse of light in evening, which delays the clock so wake up later next day
Mouse with long clock gets up later until they get hit by light in early morning which causes the clock to be advanced forwards.
Inittial human clock experiment
Left in isolation and tested when they woke up and how long they slept for
