Biological Clocks

Question 1

What are the 5 types of biological clocks?

Answer 1

Circadian, circatidal, circalunar,circaannual and semicircalunar

Question 2

What is the circadian clock?

Answer 2

Daily - every 24 hours

Question 3

What is the circatidal clock?

Answer 3

12.4 cycle, involves flow of tides

Question 4

What is the circa lunar

Answer 4

Occurs every 28-29 day cycles
Affects arise and terrestrial organisms and involves the lunar phase

Question 5

What is the circa-annual phase?

Answer 5

Yearly rhythms - drove by geogphysical cycles

Question 6

What is semi-circulunarphase?

Answer 6

15 day cycle which corresponds to a full moon affecting amplitude tide

Question 7

What is a biological clock in a human?

Answer 7

It is a block of sells called the supraschismatuc nucleus

Question 8

What is a biological clock in the drosophilia fly?

Answer 8

It is a group of cells in the lamina of the eye which create the basis of the clock

Question 9

What animals have biological clocks and why are they important?

Answer 9

They are found in organisms - and must be evolutionary important

Question 10

What do biological clocks allow organisms to do?

Answer 10

They anticipate regular changes in the environment such as night and day
They prepare for activity changes in metabolism
It coordinates internal events such as hormone release

Question 11

Does the biological clock compensate temperature?

Answer 11

They dont regulate body temperature, if temperature gets too high or low it will cause the clock to go outside of time

Question 12

Does the biological clock entrain itself to external stimuli?

Answer 12

It has to synchronise to external stimuli
If your ravel to and from different time differences the external clock cycle trains the body clock
This is known as retrainment of the body clock to its original time

Question 13

How do clocks work?

Answer 13

There are 3 input pathways known as:
Envrionemental change
Light
Temperature

These feed into clock cells (nuerons). The clock cells have cyclic intracellular mechanisms which have output pathways to drive rhythmic phenotypes which are:

Behaviour
Physiolocailly
Biochemistry

Question 14

How do you monitor behaviour in uridessy

Answer 14

Put them in 5ml tubes with 2 ml water and sand in the tube
Uridissey burrows into the sand when tides go out and when it comes in they swim in the top parts of the water before burrowing down
An infrared beam is passed across the tube and it records each time the urididessy passes the beam

Question 15

What are the results from changing the day and night cycles to rats that run on wheels?

Answer 15

First 8 days: animal was under 12 hour light basis and there is tight rhythmicity between the wheel running times
16 days: the lights get switched off - they are still rhyming but the rats clock runs less than 24 hours

Question 16

Why does the rats clock run less than 24 hours after 16 days?

Answer 16

This is due to the activity occurring earlier each day to when the biological clock would usually start
It also tells us its a nocturnal animal as its internal clock mechanism is not the same as a 24 circadian clock

Question 17

How do record clock cell activity in the rat brain?

Answer 17

Attatches a luminescent reporter to a gene involved in circadian mechanism
Each time the cell/gene is active it produces light
Each time PER protein is made it illuminates

Question 18

Why would you record clock cell activity in the brain?

Answer 18

You can see when the cells are active

Question 19

What do monarch use as a compass?

Answer 19

Monarch butterflies use the sun as a compass
They do this by compensating their flight direction according to the position of the sun

Question 20

How many chryptomes are present in a monarch butterfly clock cell?

Answer 20

2.

Question 21

What to the chryptochromes do in the monarch clock cells?

Answer 21

There are 2 of these known as chrptochrome 1 and 2
They form part of the negative regulatory part of the clock cell - mostly chyptochrome 2 though

Question 22

What is the antennae used for in monarch clocks?

Answer 22

Antennae are required for time compensated sun compass orientation

Question 23

What happens if you chop off the monarchs antennae

Answer 23

The butterfly will lose orientation and compensation occurs

Question 24

How does the monarch’s antennae work?

Answer 24

The antennae contain clocks independent from the central brain
The chopped of antennae showed that the clock genes have rhythmic and self sustaining gene expression

Question 25

Is the monarch’s antennae is controlled by the brain?

Answer 25

No, because when you chop it off the clock still works meaning that the antennae is independent to the brain

Question 26

How does the monarch’s time compensated compass work?

Answer 26

Main retina senses sunlight and the dorsal rim of the eye detects polarised light
The inputs are integragated and processed in the central complex of the brain
Blue light entrains the clock in the brain and antennae via chryptochrome 1.
Clock provide temporal information that is integrated by neural circuits.

Question 27

What do sand hoppers use to navigate?

Answer 27

The sun and moon

Question 28

How do they use their clocks?

Answer 28

They use their clocks to compensate the movement of the celestial markers- sun and moon

Question 29

What do lunar-ticks do when they get disturbed

Answer 29

They hop backwards from where they have been disturbed

Question 30

Are antennae required in solar orientation talitrus?

Answer 30

Yes, the talitrus is deficient or has no antennae they will lose their lunar orientation.

Question 31

How does the brain and antennae work in the talitrus

Answer 31

The antennae are independed in a certain time of the clock phase due to a different rhythmic expression