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How do organisms multicellular organism function and look?
- In multi cellular organism different celltypes look + function very different.
- -contain same DNA
- -gene expression differs
- different celltypes
- make different sets of proteins
Which steps can be regulated in DNA?
All steps from DNA
For most genes, which step is most important?
First step is most important.
What happen to daily Rhythms?
Most physiological +biochemical processes in body rise+fall in daily rhythms.
Internal body clock in humans runs on how many hours?
SCN located in ?
In center of brain, above optic chiasm
Which class of cells in retina detect daylight and for photopigment?
Ganglion cells and melanopsin
light sensitive depents on?
light-sensitive themselves, don not depend on rods +cones and axons to SCN
Output is from
SCN to Pineal Gland
Pineal gland releases?
- -Pineal gland releases melatonin into blood stream
- -melatonin inhibited by light
- -peaks between 2 am and 4 am
Negative feed back controls
expression of clock genes
- -Each single SCN neuron is a small clock
- -keep their rhythm even in tissue culture
- -expression of clock genes vary w/ period of 24 hrs
Circadian clock in Drosophila Fruit fly
- Transcription of Tim/per genes in nucleus
- -MRNAs to cytosol
- -translation: MRNA -Protein
- -Heterodimer formation -Tim prot + perProt.
- -Tim/per Proteins transported to nucleus
- -per protein inhibits transcription of Tim/per genes
- -less MRNA ,less protein made
- -Inhibition of transcrioption removed
- and process goes over and take 24 hrs.
Mechanism for reseting clock
Tim protein degradation in response to light
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