Q1 – Week 6 – 19-20
Week of 10/8 – 10/12
10/8 – Monday – Columbus Day – Off
He discovered America? But he only made landfall in the Bahamas and Cuba? Wait didn’t the Vikings make the voyage? Wait the Chinese mapped out the America’s 70 years before the voyage? Wait, didn’t native american Indian’s “discover” the America’s first? Wait wasn’t the America’s already here?
I think I should get a National Day! I discovered Google Forms with Checkbox grids!!! We will “recognize” next Saturday as National Grodski day and Yes you will not have to go to school!
You will have a form unfortunately…:)
10/9 – Tuesday – period 7 – Academic Study Hall
– period 8
1. Minion worksheet review.
2. Evolution presentation
a) Vestigial structures
3. Cladogram/phylogenetic Tree review –
a) Convergent/divergent evolution
b) Node = common ancestor
c) most related species in same clade
d) Branches can spin
e) Logical decent with modifications
modifications can be a loss of an allele – Vestigial structures –
but more times than not it is the addition of allele.
10/9 – Tuesday – Homework:
1. Find Test 1 – Please return Wednesday.
2: Please complete the Evolution 2 – Cladograms and biotech.pdf worksheet
and review with the key below:
*Remember that having similar characteristics among 2 organisms most often means that they have similar genetic code. So if we base our cladograms on the similarity of genes or the similarity of proteins made then we are really using the best form of comparisons to discern how closely related 2 species are.
There is an error in my key.. Can you find it?
10/10 – Wednesday – period 7/8
1. Review of Evolution 2 – Cladograms and biotech
2. Cladogram/Phylogenetic Tree Advanced Problem
Lab 1 / Lab 3
3. Collect seeds from fast Plants/Replant F2 generation
10/10 – Wednesday HW:
1. Please complete the Practice Cladogram Problem and review with video below.
You could download and print the practice problem or just look on from your screen and use a piece of paper.
2. Study for a surprise (SHHHHHH) quiz on cladograms/phylogenetic trees.
I have a hardcopy of this in my room after school. I forgot to give it out.
10/11 – Thursday – period 7 – Academic Study Hall
– period 8
1.Planting FAST PLANTS F2 Generation
2. Cladogram Quiz-
10/11 – Thursday – Homework – The homework is light tonight!
It is described below in white text color…:)
There is no homework tonight!
10/12 – Friday – period 7,8
1. Cladogram quiz review1:
a) amniotic egg, tetrapod – evolution of sea animals to land animals.
For cladogram quiz review:
2. PTC tasters activity into Hardy Weinberg
10/12 – Friday HW:
1. PLEASE HAVE your parent of guardian sign the permission slip for the AP Biology field trip on Monday, October 22nd to the Long Island Horticultural Research and Extension Center (LIHREC). This is a research facility of Cornel University.
2. Complete the Taster Packet with me with video below: I will pick up where we left off.
It is posted below:
3. Review the packet’s key based on our data collected Friday on tasters
4. Complete Form on the Hardy-Weinberg Principle: DO not start unless you completed 2 & 3.
Please Have the Form completed by 6:00 pm Sunday night. I will grade and email your score AND YOUR answers back to you. You will have to 4:30 am Monday morning to resubmit. I will enter the grade in powerschool for the form from your 2nd submission. If you submit after 6:00 pm I will just count your first submission. If you do not submit you will get a doughnut.
Please use the following worksheet that I handed out in class for the form below.
THERE IS a mistake is this worksheet.
IT should say, ” 1/27 persons of a certain population HAS THE DISEASE!!
2. If you are lost on the Hardy-Weinberg Principle then please read the Note posted below and then read the Hardy – Weinberg Taster Packet. Re listen to the lecture in class and review the key to the Taster packet.
Lecture on the Hardy-Weinberg Principle:
I will put up a new one form class today.
Hardy – Weinberg Basics –
Known as the Hardy-Weinberg Principle or the Hardy-Weinberg Equilibrium.
This principle is used to study microevolution – the change in the gene or allele frequencies in a population from one generation to the next. Specifically microevolution studies if ONE type of allele is changing in frequency from one generation to the next. Remember that evolution is “decent with modification” through NEW alleles that are selected for based on environmental pressures that develop through mutations. Mutations are rare and occur slowly through time and thus evolution is a very slow process when it comes to developing NEW alleles in organisms that have long life spans. MicroEvolution however can occur from one generation to the next if we can exam the frequency (how often) the expressed characteristic (allele) from a single gene changes.
If there is micro evolution than an allele will have a change in its frequency. Frequency is how often that allele exists in a population. If an allele exists less often (in subsequent populations) the normal distribution for alleles of a single gene will move toward another allele of the same gene that is increasing and establish a new normal distribution. This is called Direction Selection.
When a new normal distribution is established we can “see” this by physical measurements. For example: The Finches significant beak length increases in the Galapagos Islands during a drought. But with microevolution we can investigate the changes in subsequent populations without “seeing” significant changes that we can physically measure. We can identify the beginning of a shift from the old normal distribution to the new normal distribution with microevolution.
Looking back at out Peppered Moths we can see that the allele for dark wings (melonics) increased with as the melonics were selected for due to the dark colored soot that collected on their natural habitat, which increased their fitness over the light colored moths that were now more susceptible to predators. Natural selection caused a new normal distribution to occur. We normally identify evolution AFTER a new normal distribution has been established.
With microevolution we can identify exactly when a selective pressure STARTS a change in the frequency of the available alleles for a single gene.
Would we want know if allele frequencies are starting to change if certain alleles are responsible for a disease?
How do we know when there is a change in how often an allele in expressed in a population? Well we have to work from a Null position! We need to know what to expect if there is no evolution! This is where Hardy-Weinberg comes in.
Mendelian genetics was being argued against in the early 1900’s as some suggested that if Mendelian genetics were true then the dominant allele would eventually “dominate” the population. The next generation should have more dominant traits than the previous generation yet the frequency of dominant alleles seemed to stay constant from one generation to the next. It took the work of a mathematician, G.H. Hardy in 1908, to solve the problem and he did so very reluctantly as he though his work was just too simple. He was taken back how other biologist thought his work was so brilliant. Hardy with a simply derived formula demonstrated that allele frequency will stay constant unless other forces are at play.
A German physician, Wilhelm Weinberg independently also derived the equation in 1908 and thus we call the principle of constant (no change, Null) allele frequencies the Hardy-Weinberg Principle.
The forces that can change the allele frequency and thus indicate evolution is occurring are:
1. Small populations can cause genetic drift or change in allele frequency do to chance events.
When will a flipping a coin give us frequencies of heads or tails that approximate .5 ?
Only in large number of flips. So only in large population size will the chromosome segregate in meiosis in
frequencies that approximate 0.5 . How many small families have all girls or boys if the probabilities to
have a boy or girl is about .5?
2. Selective mating can cause a change in allele frequency if only the males that have certain allele will mate.
This will cause in increase in fitness of certain males with certain alleles. In our human population we may
select who we settle down with but as a population we are not eliminating all males that are tall!!!
3. There are mutation occurring. This would cause new alleles to appear or render old alleles useless for
their current application (recessive alleles). The latter would increase the number the recessive allele
frequency. Mutations that occur naturally do so very very infrequently that the chance of themm occuring is
very low. Remember Maize had 4 mutations in about 9,000 years!
4. There is gene flow in and out of population. If there are individuals of other stable populations that
migrate into or out of the population being studied there will be change in allele frequency as other
populations are subjected to different selective pressures and thus have different allele frequencies. We call
this Gene Flow. If peppered moths that lived closer to the factories in the cities migrated to another area
was isolated from factories that population would have an increase in the dark colored wings.
5. There is Natural Selection Occurring. There is a selective pressure that increases the fitness of
individuals that have a certain allele. In our modern times, especially with modern medicine, people with
many illnesses or alleles that would be unfavorable in the “wild” are not selected against anymore. In the wild it would be disadvantageous to be near sighted as we would not have glasses to help us hunt or protect ourselves from predators. But if I am not mistaken people who wear glasses have the same fitness as those who do not.
So Hardy – Weinberg Principle (Equilibrium) is a formula that predicts the frequencies of alleles in the the next generation, which will be the same as the previous generation, if there is
1. Large populations
2. No selective mating
3. No mutations
4. No gene flow
5. No Natural Selection
In our modern society these 5 conditions are essentially met and the allele frequency is expected to stay the same.
If there is microevolution occurring the Hardy – Weinberg formula will act as a baseline to judge against.
We need accurate data from our population to measure against this baseline. For example what is the current frequency of individuals that have hemophilia (a autosomal recessive disorder)?
What should it be if there is no evolution ——–> Hardy – Weinberg calculations
PTC Taster Activity –
Hardy Weinberg Introduction 1 – Micro evolution
Hardy Weinberg Introduction 2 – Taster Activity complete