human behavioral biology by robert sapolasky in standford (part 2)
that happened since then has supported the
notion of punctuated equilibrium
D
the splicing enzymes would come along
snip out the intron sections so that the
first third of the exon connected to
the middle 3rd final third to produce a
clear read out
my
this is a massive
deviation from the concept
that one gene specifies one
Protine Different splicing
can thus create very
different results
the more they goes
into the deeper
r r
Next he moves onto DNA. When we look at a DNA strong, there are periods that code
for genes interspliced with large sections (95% or so is non-coding) that function as
an "instruction manual."
The genes themselves are not always coded for in just one snippet. Often multiple
areas on the DNA will code for parts of the same gene. So you can have a section
that codes for the first third of a protein followed by a long stretch that has nothing
to do with that protein.
This is then followed by a section coding for the next third. And so on. Each of these
sections is called an exon. The in-between stuff is called introns. People deduced and
then discovered something called splicing enzymes.
David Baltimore was the first to introduce the
concept that this makes the genes modular and
opens the door to massive information within
the DNA universe. Because of this flexibility, DNA
would then have the potential to abandon the
original A-B-C model and create,
for example, an A-C combination. This will give
you 7 different ways to combine these exons,
which means there are 7 different proteins that
can result (pacing mutations of course).
the more they've realished different point of
view different enzyems splicing at different
spots So we have different items beingcreated by the same Basic DNA originalset due to different splicing enzymes beingactivated activated at different timesof life
So who is in
charge
Well whoever or
whatever
controls
these traseprition
factor including
the enviorment
which has something
to do with genetic
effects
So what qualifies as environment
gt could be something inside the cell
c
The instruction booklet part of DNA is all about
when and under what circumstances to activate
and start and stop creating proteins.
(For example, human growth hormone is released
throughout life but has peak periods.) For better or
worse this means that DNA doesn't "know" what
it's doing. Instead it's a read-out that's under the
control of lots of other factors. Among these are
the regulatory sequences upstream from the gene.
These might be called promoter or repressive
sequences that promote or repress the expression
of DNA snippets downstream. They are like
switches. And they are turned on when the right
event (internal or external) happens. These events
are triggered by transcription factors. These might
turn on single genes or whole networks in the
DNA.
On the flipside, any given gene can have a whole
bunch of different promoters that it's waiting to
hear from before it does its thing.
f
you could have
massenger
outside
from body as well
Such as scary
sight or an olfactor
massenger like a
pheromont
as a consequence of this Sapolsky
notes that the most interesting stuff
with DNA now is not the specificnature of the pro fines but rather whenit does its thing what elements
trigger it
For example maybe the cell is getting
low on energy. This could release a
transcription factor that would
result in the cell being activated to
take up more energy.
Or it could be something from
outside the cell,
such as a hormone floating around in
the bloodstream. A hormone is a blood
borne chemical messenger.
Testosterone is used as an example. It
would float far and wide and have its
effects and those effects would
increase significantly when the male
hits puberty resulting in changes in
lots of areas in the body.
DNA is covered, stabilized and protected by chromatin. And so there
is a whole world of messengers that inform the chromatin of where
and when to open up and allow the transcription factors through.
Changes can also happen that will permanently impact the
chromatin.
For example, mothering styles in rats have been shown to
permanently change elements in the chromatin in areas relating to
anxiety. This leads into the field of epigenetics. Research with
monkeys has shown a change in one area impacting 4,000 other
areas!
So moral of the story Fertilization is
all about genetics while development
is all about epigenetics
So if you have a mutation in one of
these splicing enzymes or transcription
factors the kind of changes that would
result could well fit into the punctuated
equilibrium notgradual model ofevolution
5
as we know from the previous lacture
DNA as the bigboss man is undermine as we
learn that 95 of the DNA is simply the instruction
manual this transeprition factor has a
huge impact in a if then manner
that splicing epigenetic effects impact growth
on on Here he highlights ways in which
things are interconnected envioroment geneetc
Here come to the most fun part of
Sapolsky Principal element of life in which
there is a bit of randomness chances
in even the most structured system
chaos theory Heisenberg Uncertainty
5
there is also a bit of structure in the
seemingly chaotic this might be an
important theme in evolution
ADI
j
Promoter stimulates
release of more
vasopressin o related
with this is an
increase in monogamous
https://youtu.be/TQKELOE9eY4
https://youtu.be/ovJcsL7vyrk
As promoters change,
transcription factors change.
Splicing enzymes can change
their behavior and create entirely
new proteins. Changes in
transcription factors can activate
entirely different gene sequences.
Little changes can have big
results, especially when those
changes cascade.
https://youtu.be/uIk5I86FJN0
g
mating
vasopressin
vols
perhaps humans The more vasopressin
the more likely the
f not is to be monogan
Poligamous vols when
given vasopressin
behave monogamously
There are some evidan
that Impacts human
behaviour too Sapolsk
mentions a study that
suggested that the
type of vasopressin
Promoteryou have provided
Some predictive power
of the likelyhood of
you getting divorced down the line
Naturally there are 3 million confound here
but it gives one pause in terms of the
concept of free will
one the other side of Dimorphin
Promoters seem to relate to ease of addiction
to pain killing drugs in rat The more promoters
that the rat is to exhibit addictive behaviour
pain
toward killing drugs when given the
opportunity
The more genes you
found in a species
the grater the percentage
of those genes that
code for transcription
factors
for example you have
gene A you have
one transcription factor I
but if you have A B you have 3 transerip
tipsy
A B A B so on down the line
Micro evolution is about the protines
Mame net
Changing transcription factors
changes gene networks. He
notes that a disproportionate
share of the differences in the
genetic code between chimps
and humans lie in the genes
that code for transcription
factors. This leads to the
suggestion that the most
interesting evolutionary
changes are going to be those
found in changes in the
regulatory structure of the
genes, not in changes to the
DNA itself.
a plant geneticist named Margaret McClintock. He goes through a
history of one of her experiments in which she argued for
transposable genes in plants,
i.e. genes that are actually moving around on the DNA line,
creating new proteins, networks, results. This amazing feature is
also seen in the human immune system which adapts itself
constantly in order to combat pathogenic invaders (and sometimes,
unfortunately, to combat things like the insulin production cells
in the Islets of Langerhorn - giving the person Type I diabetes).
A plant can't run away from trouble, so it had to evolve another
way to handle the world's difficulties. So they have fancy stress
response tricks, such as changing genes around to handle new
environments and challenges.
This is done by activating transposaze which
is splicing enzymes that slices out section
of the genes so that they can jump around
same kind of gene you found in animal
Predictably unfortunately pathogens also get
to utilize this trick ____
Trypanosoma brucei is a nastyprotozoan
that causes sleeping sickness in humans It
invade the body inorder to evade thehost's
immune response uses jumpinggenestochangeit'sprotine coating so the adaptiveimmune
system stays a stepbehind cause just assoon as it figures out how to kill theoriginalcoating the trypanosoma has changed it'sShild
This is called antigenic variation
imagine you are a Detective you can only
In essence the pathogen has numerous shells (for this
parasite the estimate is in the thousands) and
shuffles through them as it replicates itself. It
puts the immune system at a distinct disadvantage.
The adaptive immune system takes
out pathogens in a sort of lock
and key function, but if the
pathogen changes the locks faster
than the immune system can chisel
out the keys, you're in for real
trouble.
catch your suspect if he's wearing the
exact same outfit he had on when he
committed the crime
if he has A shirt A pair of pants 1
Pair of shoes you will catch him immediately
if he has
1 Shirt 1 Paints 2 pair of daysshoes15 11 15 11
5 11 1,125days
this same Sh it happens in body also
Nuno progenitor cells can also jump around
this is the cells in your body that have themost to do with determining who you are
being the least constrained by geneticdeterminism
So ahormonehas 2 receptoronit one on the hormone side totriggeritother that connects to the promoterthese can be mixed matched so thathormone can be triggered then gooutattach to an entirely new promoter thisisa new if then clause
the downside is
that the immune
system recovers
it sometimes overshoot
the original mark
endsup getting hyper in it hyper state it
became over reactive the next thing you
know you have an auto immune disease
which is more common after pregnancythis could be dangerous some autoimmunedisorder such lupus are severe enough that
the affected will be advised to avoid pregnan
this is
where
spiritual
guru's
form
their
belief
Glucocorticoids are stress hormones that suppress the immune
system (there's a lot more to it, but in brief, they suppress it by
reducing the inflammatory response). A slight clip and a little
shuffling and you can create the new if-then clause if there's
progesterone around suppress immunity. What's this about?
Pregnancy. This if-then statement prevents the immune system
from attacking the fetus.
Next up are copy number variants. This is the world of multiple copies
of the same gene. This can allow for experimentation with one back-up
copy. At the same time, there can be problems linked to it, such as is
seen with schizophrenia.
The multiple copies of genes may account for "irreducible complexity,"
i.e. how can an eye pop up out of nowhere? If the organism has
multiple copies of sensory genes and is able to experiment with one
without sacrificing the other, it could develop a feature incrementally,
slowly growing an eye while using sound and tactile information for
guidance until such time as the eye starts working. (This can account for
evolution's production of vision while leaving a very big door open in
regard to what's out there that we haven't evolved to see.
This is the whole world of intuition and spiritual belief. This is the
whole world of wackos that claim they can sense things others can't. Or
is it?)