(uplifting music)
- Hey again, scientists!
Welcome back for lesson
five of Natural Selection
with me, Ms. Jetha, coming at you again
from Seattle, Washington.
Here's what you'll need for this lesson.
A pencil or a pen,
some lined or blank paper,
and optional but highly encouraged,
a family member, friend or a pet
that you can check in with,
a computer logged in to Amplify
and if you have one, a Lesson 5 Packet,
that you received from your teacher.
All right, let's have everyone
get those minds working
and let's warm up with
this little exercise here.
Here's what I would like you to do.
Turn and talk to a friend or family member
or jot your responses
down on a piece of paper
about the following questions which refer
to this diagram right here.
What do you notice about the traits
of the offspring compared to the parents?
Now, first thing I want you
to notice on this diagram,
it's set up kinda like a family tree.
So on the top of the diagram here,
we have parents and at the
bottom here we have offspring.
So parents and offspring.
And this question is asking you to compare
the traits of the offspring
compared to the traits of the parents.
So what do you notice there?
Second question.
Where do organisms get their traits?
Start thinking about this.
We kind of understood
a little bit about this
with our reading about
jellyfish from the last lesson.
So think about how would
you answer this question.
Where do organisms get their traits?
Pause the video, grab someone near you,
text a friend, Snapchat them,
whatever you'd like to do
and think about this diagram
and these two questions.
When we have someone to talk to,
we can really process a little bit more
about what's going on.
So pause the video now.
Go ahead, do it.
Okay, so I'm gonna share with you now
some of the things I
notice about this diagram
and reference these two questions
that we are thinking about
as we start this lesson.
So first thing I noticed, parent one here,
his name is Otis and he has a brown body,
he's got purple stripes on his abdomen
which is the back part of his body
and he's got these hairs
coming off of his legs.
The hairs are there but comparatively,
Anne has got a lot more hairs on her legs
and Anne's body is white.
I can see that she has
a black set of stripes
on her abdomen.
And so I noticed that
these two parent spiders,
Otis and Anne, are very different
in the way that they appear.
That makes me think about how their traits
for things like their body color
and their stripe color and their hairs
on their legs are pretty different.
So this makes me wonder about like,
oh wow, I wonder, like, their offspring
are probably gonna be interesting too.
So taking a look at their offspring,
I see there's one, two,
three offspring spiders
that have white bodies, kinda like Anne,
and then one offspring spider
that has a brown body like Otis.
Now in terms of stripe color,
this is very interesting.
There's all sorts of
combinations going on here
from what I notice.
In terms of stripe color,
I see here that there's one, two, three,
these three offspring spiders
have black stripes on their abdomen.
And this is a really unique combination
'cause we have the black
on top of the brown
which we did not see in the parents
which is super interesting.
And then we have one spider that does have
that purple stripe color like Otis does.
But this is interesting too,
the offspring spider,
okay, that's interesting,
it has a purple stripe
color on the white body,
which we also did not see before
in the two parent spiders.
Okay, let me think about this,
the hair on their legs as well.
So I can see there's lots
of variation in the hairs.
None of them have as many as Anne
but a lot of them have
more hair on their legs
than Otis does, so that's
really interesting to me.
So I'm beginning to wonder
like how did this happen?
There's lots of different
combinations going on here.
I definitely wanna know more about that.
Now in terms of the second question,
where do organisms get their traits?
Well, I remember from the reading
there's something about genes,
there's something about proteins
and those two seem to be connected
in the way these traits like
body color or stripe color
or hair on the legs is expressed.
So I think there's
something going on there,
that connection between
genes, proteins and traits
but I can't remember exactly.
Well, we're gonna dive in more of that
and we're gonna use spiders
as our subjects, so to speak,
to understand a little bit more
about the connection
between those three things
like we began talking about last lesson
with those jellyfish.
All right, everyone.
So what we're gonna do now
is we're going to go into a simulation
that's actually not the
natural selection simulation
and what it will allow us to do
is be able to zoom in
into that molecular scale
and be able to see that connection
between genes, proteins and traits.
Now, in this simulation you
will see a spider population
and some of you may actually remember
the simulation from another unit
that you've done previously.
In this simulation we'll be focusing
on the feature of stripe color
for this population of spiders.
Now here are the two
spiders we're particularly
going to be concerned with.
The first is Otis and
Otis has a brown body
and blue stripe color on his abdomen,
which is the back part of his body.
The other spider we're gonna
be particularly concerned about
is Ruby here and Ruby has a yellow body
with black stripes on her abdomen.
All right everyone, so here we are
in this different simulation
and we have Otis here.
As we mentioned before,
Otis has a brown body
with blue stripes on his abdomen.
Now, I can see a lot of moving parts here
and there's lots of
different things happening.
So let's make sure that we have a couple
of the essentials down here
as we're looking to understand
at the molecular scale
what is going on that allows
for these traits to be expressed.
And particularly in this simulation
what we're thinking about
is how is this trait
for blue stripe color
be able to be expressed.
The first thing I want you
to notice are Otis's genes.
In this right hand corner in the box,
we can see Otis's chromosomes.
Now, remember, chromosomes
are those bundles
of tightly wound DNA and that's
where the genes are located
on an organism's chromosomes.
If we look at Otis's genes,
we can see he has two T2 genes
on this set of chromosomes.
So he has a T2 and a T2.
Now, remember, those
genes provide instructions
for making proteins.
Well, let's take a look at
which proteins Otis has.
So these T2 genes provide instructions
for making the number two protein.
I can see that in his cell
that those T2 proteins,
those protein number twos,
are floating around and
they kinda look like
a rectangle with a rounded edge,
a rectangle with a rounded edge.
Now, I want you to notice
something else here as well.
Right now this two protein,
number two protein,
is connected like a lock and
key with another molecule.
We can see that going on here as well.
Now let's take a look at what's happening
and how that lock and key kind of model
allows for the expression
of the blue pigment
that is in Otis's stripe
color on his abdomen.
Okay, so what we know is that Otis
has these T2 gene versions,
which we can see here.
And those provide instructions
for the number two protein right here.
Now, I'm going to zoom
in a little bit further.
And what's important to note here
is that those genes are
providing instructions
to make the protein in
a very particular shape
and that particular shape
allows for the protein
to be able to fit in another molecule.
And when that protein
fits into that molecule,
that allows for the expression of,
for example here, the blue pigment.
So it's kinda like that lock and key
that I mentioned before.
The genes provide
instructions for the proteins
to make this particular shape
that fits together with a larger molecule.
And when that fit happens,
then it unlocks a blue
pigment to be produced
which is what gives Otis
that blue stripe color
on the back of his abdomen.
Okay, so now I remember we
were concerned about Ruby too.
Now, remember Ruby was a spider
that had a yellow body color
with black stripes on her abdomen.
So I'm now wondering how are the genes
and proteins different
between Otis and Ruby
that's causing Ruby to
have black on her abdomen
while Otis had blue.
So let's take a look here.
Again, lots of moving parts
so let's make sure we
walk through this together
to see what's happening
and why these differences
in stripe color are occurring.
First, let's take a look at Ruby's genes.
Her gene versions, again
these are her chromosomes,
those tightly wound bundles of DNA,
and her genes are on those chromosomes.
Now, Ruby has T2 and T3 gene
versions on her chromosomes.
So what does that mean?
Again, those genes are providing
instructions for proteins.
So what I think this shows here
is that Ruby is able to
make the number two protein
and the number three protein,
which is different than what
I just showed you with Otis.
So we have these T2, T3 gene versions,
which allow for the number
two and number three protein
to be created in Ruby's cells.
We can see that here in her cell,
we've got this number two
protein floating around
and we have this number three
proteins floating around.
Now, the number two protein,
like I mentioned before,
is kinda like a rectangle
with one rounded edge
but this number three protein
is kinda like a crown, it
has two pointy edges on it.
And so we can see here that Ruby
has both the number two
and number three protein
and that's because her genes
are providing the instructions
for those two proteins to be made.
Now let's zoom in and see how this works
in terms of shape and
that lock and key model
that we talked about earlier.
Okay, so just like before, we
can see our number two protein
fitting in with a larger molecule,
and that therefore is
producing the blue pigment.
Let's see that right here.
Right here we can see
that number two protein
connecting with a larger molecule
and that is producing this blue pigment.
Now, on the other hand,
we also have that number three protein
because we have the T3 gene.
And we can see here that
that number three protein
is also connecting with
those larger molecules
to be able to produce this black pigment.
So we have both the number two
and number three proteins
connecting with larger molecules
to create that blue or that
black pigment respectively.
Now here's a question.
I am wondering what might happen
if I changed one of Ruby's gene versions
so that it would replicate Otis's
feature for stripe color?
What do you think would happen
if I changed Ruby's T3 gene to T2?
Pause the video and I want you to turn
and talk to someone and predict.
What do you think might happen
if I changed Ruby's T3 gene version to T2?
Pause the video, talk about it
and then I'll be right back with you.
Okay, so I hope you made a prediction
and hopefully that was
based in this understanding
that genes provide
instructions for proteins.
So we're going to change
Ruby's gene, T3 gene,
we're gonna change that to a T2.
And I want you to see what happens here.
When we changed Ruby's
gene version from T3 to T2,
now all that she's making
is that number two protein
and therefore her stripe
color has now changed to blue.
What is happening here is that the change
in that gene version changes the protein
and that structure of the protein
that can fit into the larger molecule
and thus only the blue
pigment can now be produced.
So changing that gene version
changes the protein and the structure
of the protein that's created,
which changes what that
protein can fit into
and thus changes the pigment color,
which then changes the
stripe color that Ruby has
which is now blue instead of black.
All right, so let's take all
of these into consideration
and so some sense-making.
There's a lot going on here.
And we need to make sense out of it.
So grab someone that's near you,
text a friend that's also
watching this video with you
and let's make sense of
everything that we just saw
'cause that was a lot going on.
So what we can understand
from what we just saw
is that genes provide
instructions for making proteins,
and these proteins have particular shapes.
So the genes also dictate
what shape that protein is.
Those proteins,
the way they fit together
with the larger molecules
allow for traits to be expressed.
This is what we call a central dogma
or central concept of genetics in biology.
Genes provide instructions for proteins
which are then expressed as traits.
And remember that shape of the protein
is particularly important
because it's gotta be able
to fit with that larger molecule
in order for, in our case,
a pigment to be produced
for the stripe color of the spider.
And we can see that here
with the different gene
version that Ruby had,
those gene versions,
that difference provided
different instructions
which was a different shape protein
which fitted differently with the molecule
that created the black protein.
So lot going on here.
Remember, genes provide
instructions for proteins
which are then expressed as traits.
Okay, so let's boil this down
to a couple of key concepts
that are fundamental to our understanding
and will help us explain
the phenomena of the newts
that we have been investigating as well.
Grab your pencil, you're
gonna need to write this down.
You can write it down in a tracker
if you're using one of those.
I'm just using a little notebook.
You can put it down in your notebook.
It's gonna be essential
that you write this down
to help further our understanding.
Okay, so the first key concept.
Genes are instructions for
making protein molecules
and protein molecules
determine an organism's traits.
Second key concept.
Individuals inherit their
genes from their parents.
Genes, and therefore
traits, in a population
are passed down from
generation to generation.
We're gonna see that a little bit more
with our next activity
but make sure you have this written down
either in your tracker or your notebook
so we can expand upon
them a little bit later.
So now we have a better understanding
of where individuals in
population get their traits.
We know that they get their
traits from their genes
and those genes come from
the parents of organism
who have passed down their genes
through the process of reproduction.
Now those genes then provide instructions
for making proteins in a particular shape
and those proteins can then
attach to larger molecules
which then allow for particular traits
such as stripe color in
the spiders we saw before
to be expressed.
So now the question becomes, well,
then, how do some traits become
more common in a population?
And we know that the newt
population became more poisonous
because of the presence of
snakes in the environment
which caused the trait for poison level
to become an adaptive trait.
But how did it become more
common in the population
is our next question.
Now, our park visitors have
some suggestions for us
on how exactly this happened.
The first suggestion that they have
is that poison level 10 is the
most common in the population
because the newts with this trait
were able to live longer than other newts.
Their next suggestion
is that poison level 10
is the most common because the newts
with the trait produce
more than other newts.
So let's check this out in our simulation
and find out some evidence and data
that may support or refute
either of these claims.
So, as we go into our simulation,
we're going to be
investigating this question.
How do some traits become more common
over many generations while
others become less common?
Now, grab your pencil or
pen and we need to create
a data table in your notebook
for you to record this data.
Here is what your data
table should look like.
So with your pen or
pencil and your notebook,
you can grab a ruler if you
want to be particular about it,
you are going to create this table
in which we will be recording data
for each of these different Ostrilopes
with different color levels
of one, four, seven and 10.
And we'll have five different trials here.
And what we're gonna do
is we are going to follow
Ostrilopes with this particular color
and we're gonna count how
many times they reproduce
while we're watching the simulation.
And that will give us some evidence
as to which Ostrilope colors may reproduce
more or less than others.
So go ahead, take a minute
with your pen or pencil
and copy down this data table
so that we will have a
space to record our data.
Here we are in our natural
selection simulation.
And what I'm gonna do is I'm gonna click
on this hamburger menu up here.
And if you're following along on Amplify
on your computer or other
device, you can do this as well.
So I simply went to Amplify,
clicked on the Natural
Selection simulation.
And where I'm gonna go is go
to our Reproduction Claims
in the hamburger menu there.
I'm gonna load those reproduction claims.
And I'm gonna go ahead and get
set up with our first trial.
And in our first trial I'm gonna start
with blue number one.
So here's what I'm gonna do,
I'm gonna zoom in over
here and I'm going to look
for an Ostrilope that has a blue,
number one color level.
So here is one right here.
And then when I run the simulation,
I can go a little bit closer
so I can follow my blue
number one Ostrilope.
And what I'm going to do is
I'm gonna run the simulation
and count how many times my Ostrilope
with a color level of one reproduces.
So I'm gonna go ahead and run it
and we'll count together how many times
this Ostrilope is able to reproduce.
Now, if this Ostrilope gets
eaten before reproducing,
he'll just get a number
zero in our data table.
So let's go ahead and watch and see
how many times this Ostrilope reproduces.
All right, I see this
Ostrilope is reproducing once.
And then, unfortunately, he got eaten.
So I'm gonna take my pen or my pencil
and in my data table that I
just drew in my notebook here
I'm gonna write down a one
for trial one blue, one.
All right, we just did
trial one, blue one.
Now, we're gonna zoom in again.
I've reset my simulation.
And I'm gonna look now for an Ostrilope
that has blue number four,
a blue number four color.
So that leads me to believe
it'll be kind of bluish green.
So let me see if we can find one.
There's a three, here's a four.
Fantastic.
So I'm gonna run the simulation
and again we're gonna count how many times
the Ostrilope with blue number
four color-wise reproduces.
So let's go ahead and count how many times
this Ostrilope reproduces.
Our Ostrilope is just
eating at the moment.
Oh, he's finding a mate.
So that's once.
That's twice.
That's three times it's reproduced.
And then he gets eaten.
So I'm gonna document that with my pencil
on my data table right here.
Trial one, blue number four
reproduced three times.
So make sure you have that
in your data table as well.
All right, so I've
reset my simulation now.
And now I'm gonna be looking
for yellow number seven Ostrilope.
So let me zoom in here.
And I wanna find a yellow number seven.
That's a number eight.
So let's find a yellow seven.
That's a nine.
There we go.
Here's a yellow number seven Ostrilope.
And again what we're gonna do
is when I run it we'll
count how many times
this particular Ostrilope reproduces.
Oh, looks like he's found a mate.
Okay, this is number
one time it reproduces.
Notice how the Carnithons are
just kind of passing it by.
Here's a second time it's reproducing.
Third time it's reproducing.
And then it has gotten eaten.
So I'm gonna pause the
simulation right down there
and I'm gonna go ahead and write down
this Ostrilope yellow number seven
also reproduced three
times before it was eaten.
And that's again trial
number one, yellow seven.
It reproduced three times.
All right, so I reset my simulation again
and now I'm looking for an Ostrilope
with a yellow color 10, a yellow color 10.
And so I feel like this one might be one.
Oh, that's close, it's
a yellow number nine.
Let's see if I can find a yellow 10.
That's a seven which we just did.
Yellow 10.
Maybe one of these.
Oh, clicked on the wrong
one, that's a nine.
That's a nine.
Here's a 10, fantastic.
So I'm gonna zoom in
and here's our friendly little
Ostrilope level 10 color.
And I'm gonna run this simulation
and again we're gonna count how many times
this particular Ostrilope reproduces.
Okay, unfortunately that one
got eaten really quickly.
So I'm just gonna mark that
down as a zero on my data table.
So I've taken my pencil
and I've written down zero
where it says trial one, yellow 10.
Now that's only one trial.
We need more evidence and more data
so that we can make a further conclusion
about the population as a whole.
So we're gonna do trials two,
three, four and five as well.
Same thing, we'll look
at the Ostrilope color
that's designated and we'll count
how many times it reproduces.
All right, we are in trial two, folks.
And I'm looking for blue Ostrilope
with a color level of one.
And we're gonna zoom in
and go ahead and count
how many times this Ostrilope
reproduces for trial two.
Let's go ahead and watch.
And it got eaten right away
before it could even reproduce.
So I'm gonna mark that down as a zero.
Let's go ahead and reset
and go straight into Ostrilope
with blue number four.
Let's go ahead and find one if we can.
There we go.
Here's a blue level four Ostrilope.
And let's count how many
times it reproduces as well.
Okay, that's once that it reproduces.
And then unfortunately it got eaten.
So for blue, Ostrilope blue four,
for trial two that was only a one.
Gonna go ahead and reset.
And let's find an Ostrilope
with a yellow color seven.
Fantastic.
And we'll zoom in a little
bit further so we can see.
And we'll run it.
And count how many times it reproduces.
So that's once.
That's twice.
Notice how some of the Carnithons
are just passing it by.
That's three times.
That's four times.
Five times.
Six times.
Seven times.
This Ostrilope is camouflaged very well.
So we're at seven times so far.
Taking a little bit of
patience in waiting.
And then it has gotten eaten
after seven times of reproducing.
So for trial two, this Ostrilope
with yellow color seven
reproduced seven times.
And let's do our last one
for trial number two, folks.
This is a yellow color 10 Ostrilope.
I'm gonna go ahead and zoom in
and find a yellow color 10.
That one was a nine.
Make sure I reset.
Here's a yellow 10.
So we're gonna follow this Ostrilope
and see how many times it reproduces.
Okay, unfortunately that
one got eaten right away.
So I'm gonna document
that on my data table
as a zero for the amount
of reproduction it did.
We're gonna go ahead and
reset and let's move on
to trial number three now as well.
(uplifting music)
(energetic music)
