Dictyostelium differentiation

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Dictyostelium differentiation
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Announcements
next two lab. sessions are Dictyostelium. we
will meet next week to update on our experiment
and take a quiz on Dicty The week after, there
is no lab session and you should be working on
the lab report (50 points) for dicty that is due
in the week of November 15th. So, find a new
group to work with rather that the old
one. today there is in class prospectus (13
points) about what you will do.
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Today
hypothesis testing model organisms
Dictyostelium discoidium prospectus for
Dictyostelium differentiation
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Hypothesis
hypothesis is basically an idea or a question
e.g does light wavelength has any effect on
Dictyostelium differentiation. usually based on
previous observations e.g the rate of
dictyostelium differentiation varies it has
prediction(s) e.g certain wavelength will
speed up or slow down the rate of
differentiation the researcher task is usually
to test these predictions e.g grow
dictyostelium in certain wavelength and
compare the rate of growth to a control
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Model organisms
It is not always easy to test hypothesis
specially in biological system (or even any
other type of science discipline). e.g the
Moon is made up of cheese!!! The hypothesis
has to be testable. In biology, there some
organisms that are easy to deal with and
manipulate E.coli D. melanogaster C.
elegans D. discoidium A.thaliana
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Dictyostelium discoidium
it is a social amoeba (unicellular
eukaryotes) its habitat is upper layer of forest
soil it is also known as slime mold it shows
sexual and asexual life cycles adverse
environmental conditions mainly starvation
trigger the switch between the two life
cycles. the organism is a linkage between
unicellular and multicellular life
style multicellularity is clear in the asexual
cycle cAMP is the signal of communication
between cells D.discoidium feeds on bacteria
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Dictyostelium discoidium
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I got the picture
choose environmental condition -temperature
-light (directionality or dark -cAMP
-charcoal - PH you will be supplied with 6
nutrient agar plates with E. coli lawn in the
center of the plate. one of the has to be the
controle (positive)
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I got the picture
- pipette different volumes of your chemical
(1-5 drops) 10?l each on the top of the disk
-let the plate stand for 5 m for those who
chose light effect, read the protrocol in the
lab manual. for all the experiments
-inoculate the center of the plate with 100?l of
Dictyostelium culture. Mark this point on
the plate temperature lab room
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I got the picture
what exactly am I looking for how fast slugs
and fruiting bodies, with different
environmental conditions, are formed. where
these things are supposed to be D.
discoidium growth on agar looks like waves
that are moving toward the periphery
(looking for food). Where do you think the
starving cells will be? when I check my plates
start Moday and do it daily till you reach the
endpoint
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I got the picture
how do I collect data set a number of
microscopic field that you are going to
examine and count the number of fruiting
bodies and slugs and compare them across
plates. what is the homework for this week
non. However, two weeks from today a
prospectus,on the hypothesis you want test and
how you are going to do it, has to be turned in