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PSY397 - Exam Questions Answered.docx

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Martin Ralph

2010 MAY EXAM Let‟s discuss the answers here: I‟ve started with 6 questions. Some of them we have answers for in the term tests. But it would be helpful if we could go through all the exams with answers all in one place. Whoever created this googleDoc, a big thanks! it’s been very beneficial for everyone! The peak number of people participating at one time was 14 people, which is at least 1/3 of the whole class. LOL ATTENTION ON BURING Qs [your feedback is greatly appreciated] * question 20 answers seem to be debatable. * ALSO anyone have opinions on 19?? we need a little more for 5 marks worth, no? *lots of ambiguity in the answer for Q15 *What about questions 8-13? *Q 7 has no answer yet ANSWERS The diagram in the first slide in Oct 29 (Powerpoint Oct 22B, slide 22) Loop 1. 1) CK1e causes a CRY:PER dimer to form 2) Once dimerized they enter the nucleus 3) This inhibits (-) the TF (Bmal:CLK) and suppresses cry, per, ccgs, rev-erb genes 4) When ccgs is not suppressed it promotes (+) phosphorylation of PER and joining to CRY by Ck1 --- doesn‟t ccgs cause Ck1E to phosphorylate PER?? Loop 2. 1. rev-erb does joins to something? to reenter nucleus? 2. causes production of bmal1 which becomes a protein? Assuming that those two little circles are CRY and PER? Thats the best I can do, idk how much of it is right so if anyone knows whats happening please fix it. Hopefully it at least gets the ball rolling Loop 1 - NEGATIVE feedback loop for PER and CRY. PER and CRY inhibit themselves. Once there is enough of PER and CRY, they turn off transcription. Loop 2- POSITIVE feedback loop for PER and CRY. (not sure how). NEGATIVE feedback for Bmal and Rev-ERBa (not sure how) -- anyone know how???? Okay -- I got it!! --------- Bmal POSITIVELY feeds back to PER and CRY because it is a transcription factor for PER and CRY. Loop 2 NEGATIVELY affects Bmal and Rev-ERBa because making PER and CRY causes rev-erba to be inhibited. Rev- ERBa is made from rev-erba and INHIBITS Bmal1 transcription. just a small correction (I made sure w/ prof on this):Loop II produces rev-erba gene, which negatively inhibits transcription of Bmal1. Rev-ERBa is produced by the gene in the nucleus. (the positive sign besides Rev-ERBa refers to other transcription factors.) Here’s the slide all the info is from. Im good with that explanation. How in the world did u copy/paste the image?? how come I can‟t paste pictuers using my computer??? I can't either :S..... only from a a link Oh.. all I did was click SELECT on my PDF and then dragged the rectangle over the picture and pressed copy. I have a pretty old mac but I‟m sure they wouldn‟t take that function away. I don‟t know how to do it on other computers, but I think you press CAPTURE. that‟s exactly what i did. FAILED TO PASTE AN IMAGE: One or more images could not be pasted. Images that are on your local disk or in non-standard formats cannot be imported automaticall”. ___________________________________________________________________ ___ ANSWERS: from lecture on Oct 22B the tau mutation (1) reduces the rate of phosphorylation of PER protein by CK1e, and (2) reduces release of CK1e from the PER:CRY transcription factors result, PER:CRY dimers accumulate faster, and so the transcription translation feedback loop occurs sooner, thus the period is shorter, causing phase advance. What gene causes the tau mutation? good question -- i’m not sure On Wiki it is MAPT gene -- does this sound familiar to anyone? Or period gene?? never heard of it lol, i find this proff wants you to know things he doesn't specifically state allot ___________________________________________________________________ ___ ANSWERS: -retina projects to IGL via optic tract [using RHT] -IGL lesions affects photic responses -IGL lesion abolishes non-photic phase shifting -Neuropeptide Y from IGL into SCN causes non-photic shifts [using GHT] -electrical stimulation of the IGL produces nonphotic phase shifts in hamsters -bilateral lesions of the IGL in hamsters results in both (1) reduced circadian response to changes in light intensity in LL, and (2) reduced circadian response to novelty great answer ___________________________________________________________________ _____ ANSWERS Remove the tissue from the presumed site and observe whether the physiology or behaviour measured (squirting) becomes arrhythmic ___________________________________________________________________ _____ ANSWERS - Removal of the site would have to cause arrhythmicity. - replacement should restore rhythms - when transplanted between species the restored rhythm matches that of the donor and is distinct from that of the hosts ___________________________________________________________________ _____ ANSWERS 1) siphons 2) neural gland 3) anterior surface ___________________________________________________________________ _____ ANSWERS OCT29 - The nucleus determines the phase and of the circadian rhythm of photosynthesis. The rhythm, however, doesn‟t need the nucleus to be present. The anucleate algae can reset the phase of the photosynthetic rhythm when the LD cycle was inverted. The photosynthetic rhythm persists even after the nucleus is removed. -nucleus determines the phase of the circadian rhythm of photosynthesis -but, nucleus is not required for the rhythm, it just determines the phase ... perhaps... ___________________________________________________________________ _____ ANSWERS The fact that theres two types of responses, photic and non-photic? - idk about this IS THIS RIGHT?? I‟m not sure.. I‟ve been trying to find the answer Ithink we should include the two types of oscillators...1) Circadian Executive oscillator= SCN and 2) Circadian Operations oscillator = peripheral oscillators.??????and the evidence is the ZT03 and ZT11 experiment. Where the animal remembers the ZT11 training even when tested at ZT03 after 18 days. You might be right.. I was also thinking of the fact that we anticipate things during the day, like eating our lunch. That has nothing to do with the LD cycle that can entrain our sleep-wake cycle. We talked about this on Nov 14 with rats. They have an oscillator that anticipates food (and they run on their wheel in anticipation) which is separate from their sleep-wake cycle. I think what I just said is just an example of what you said. I‟m reading my notes and it says peripheral oscillators are running when you put a rat on meta-amphetamines. ___________________________________________________________________ _____ 7. Design an experiment to identify the presence of a circatidal clock?? I believe this has to do with what we covered nov 14th, although I’m not entirely sure how to answer this. Fireflies synchronize to the full moon. You could take them out of their natural environment and see that their circadian rhythm is still running, but their circatidal clock will be arrhythmic. REALLLY not sure.. Anyone else?? ___________________________________________________________________ _____ 14. How did SCN transplant experiments in hamsters the adaptive significance of having a clock? - tau was transferred -healthy SCN transplanted into old hamsters gave them healthier (less fragmented) rhythms, and greater longevity -longer lifespan = more time to reproduce = more likely to have more offspring ___________________________________________________________________ ___ 15. A population of amphipods (tau = 24) is collected at 9am on a beach in the Northern Hemisphere with water directly to the W. Indicate the direction of escape for each assuming they do not immediately see the water (6 points) a) If the population is released in sunlight? b) If the population in released with overcast sky? c) If the population is released after 3 days in constant conditions onto a beach facing SW in the direct sunlight at 3pm? d) If the population is transported 3 time zones to the east in constant dark, then released at 3pm local time? e) If the population is transported to a sunny beach in the S. Hemisphere (same time zone) and released the next day at 3pm local time? f. If the population is transported to a sunny beach in the S Hemisphere and released 6pm local time? ANSWERS *assume amphipods move towards land on home beach when no visual cues present* a) E b) random c) SE animal will escape according to home beach (not according to new beach) - should this be E then? correct d) SE time zones increase as you go east correct? meaning 3pm in an eastern timezone is 12pm in a western. Therefore the animal thinks its 12 and goes SE? you are right! e) E animal try to go to the sun at 3PM, in order to go East. the sun is at NW @ 3PM in S Hemi. so the animal moves South. my reasoning for E here was that its the same time zone so the animal knows whats up, idk if thats true though. at 3PM: sun is in NW at southern hemi, but the sun is in SW in northern hemi. If it‟s 3PM in northern hemisphere, animal goes 135 degree CCW from the sun at SW, in order to reach east. in southern hemisphere, animal goes 135 degree CCW from the sun at NW, which is South f) SE the sunset in the West @ 6PM, which is direction of water. the animal moves East. anyone agree? disagree? ___________________________________________________________________ ___ 17. Describe 2 primitive reason for having biological clocks. ANSWERS Anticipation: Preparation for regular changes in the enviroment Organization: optimal temporal sequncing of molecular, cellular, tissue, and behavioral activities. ___________________________________________________________________ ___ 16. True or False a. photoreceptors for the mammalian circadian system are located in the hypothalamus. b. a circadian clock in a lizard is always found in the pineal gland. c. Circadian pacemakers in Bulla are located in the visual retina. d. mice without eyes do not have circadian locomotor rhythms in LD cycles. e. A circadian rhythm in cyanobacteria, kai proteins, can be demonstrated in a test tube. f. a sparrow with neither eyes nor pineal cannot synchronize with an LD cycle. g. A cockroach without optic lobes is rhythmic in DD. h. A fruitfly without PER remains rhythmic in DD. i. A hamster with bilateral lesions of the IGL cannot entrain to an LD cycle. j. The melatonin rhythm in humans does not change through the year. k. the melatonin rhythm in nocturnal and diurnal mammals is inverted (180 degrees out of phase) l. In mammals, circadian oscillators are found only in the SCN. ANSWERS a. False b. False c. False d. TRUE e. True? - because Kai A,B and C autophosphorylate, inhibit and promote all by themselves ah ha, you're right.... wikipedia saves the day - scroll down to “molecular mechanism of cyanobacterial clockwork” beauty haha f. True g. False - slide 31, Oct 10th ---- TRUE (FALL 2010 MIDTERM) h. False? - the fruitfly need a PER:TIM dimer to inhibit clock rythms lecture Oct 10, slide 36/39 - says working period gene is required for overt expression of rhythmicity .... so yeah false... I think i. False j. False k. False (?) because melatonin synthesis is inhibited by light, so it would be produced based on the LD cycle, not the activity pattern of the animal sounds right to me, were assuming it remains the same, and then the animals use this cue differently? ... yes, I just googled this to confirm that nocturnal animals are active during the melatonin peak: alright l. False ___________________________________________________________________ ___ 19. How do “night break” experiments indicate that a circadian oscillator underlies photoperiodic time measurement? (5 points) ANSWERS Night breaks which occur 24 hours after a light interval (day) are able to disrupt photoperiodic time measurement. when light falls during an organisms subjective night, they respond as if on a long day. two examples of plant on “night break” schedules. The short day plant flowers on the short photoperiod, but flowing is stopped if there is a short pulse of light at night. The long day plant responds in the opposite way. i thought night breaks have random light pulses and resonance has a scheduled light pulse ___________________________________________________________________ ___ 20. In mid spring in the N. Hemisphere, starlings are trained to find food at 9AM (in the SE corner) of an outdoor arena. Assuming they use their circadian clock and the location of the sun. (12 points) a) In what direction are they predicted to search at noon the next day? b) In what direction would these birds search at noon, if the sun is hidden, and an image of the sun is provided by a mirror to the north? c) If after training, these birds are put in constant conditions, then tested three days later at 9am in what direction will they search assuming their circadian periods average 24hrs? d) In what direction will the animals in (c) search, if their circadian periods average 25 hrs? e) If after training, these birds are ent
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