Explain the diagram
Announcements
•Today Collab
•Writing assignment
-math with decimals story math
•A4 due Thurs
Evolution on a micro level
•Looking at alleles (A, a)
•Looking at the DNA
• DARWIN DIDN’T KNOW DNA
How do the alleles change after bottle neck?
• The Bottleneck Effect: type of
genetic drift resulting from a
reduction in population
(natural disaster) such that
the surviving population is no
longer genetically
representative of the original
population
Bottle Neck
Genetic Drift
• A change in the gene pool of a
population over a succession
of generations
• 1- Genetic drift: changes in
the gene pool of a small
population due to chance
(usually reduces genetic
variability)
Genetic Drift Animation
• http://highered.mcgrawhill.com/sites/dl/free/0072835125/126997/animation45.html
A3
1) Inquiry activity—
On whiteboards make a large (50) and
small population (10) with variation.
Show that small populations are more
likely to have a shift in allele frequency
(genetic drift) than large populations
when a bottle neck event occurs
2) A3 diagram interpretations
A3
Move tables
Take out A 2 mastery
checklist
+ guppies + chepo
Now: A-2_Level 1
Practice Test
A-2_Level 1 Practice Test Answers
1) A was a collection of new habitats
2) B Natural selection can occur in guppies within a few
generations
3) E 190mg
4) A Characteristics acquired during an organism's life are
generally not passed on through genes.
5) D More small-beaked birds dying than the larger-beaked
birds. The offspring produced in subsequent generations have
a higher percentage of birds with large beaks.
Today’s Agenda
1) FRQ—Writing + Scoring A-1_Level 3.
Scan 1-10, 11 write in. Turn in FRQ and
Grid-ins stapled together
2) A2_Level 3 Assessment
(must show completed mastery checklist)
3) Evidence of evolution—Humans and
Chimps
Evolution is one of the unifying themes of biology. Evolution involves change in
the frequencies of alleles in a population. For a particular genetic locus in a
population, the frequency of the recessive allele (a) is 0.5 and the frequency of
the dominant allele (A) is 0.5.
(a) What is the frequency of each genotype (AA, Aa, aa) in this population?
What is the frequency of the dominant phenotype?
(b) How can the Hardy-Weinberg principle of genetic equilibrium be used to
determine whether this population is evolving?
(c) Identify a particular environmental change and describe how it might alter
allelic frequencies in this population. Explain which condition of the HardyWeinberg principle would not be met.
Period 4 Seating Chart
• Team 1-2—
• Team 3—
• Team 4-5—
• Team 6—
• Team 7-8—
• Team 9—
• Team 10--Eddy
Period 1 Seating Chart
After you find your seat go to the black table and
then pull out A-2 and A-3 Checklists
• Team 1-2—Riana, Erik, Jesse, Laura M, Carlos
• Team 3—Jessica, Quinton, Michelle, Kaitlin, Jose, Pedro
• Team 4-5—Joseph C, Austin, Kayla, Christian, Desarai
• Team 6—Laura C, Abner, Richard, Brittany, Daisy
• Team 7-8—Shirley, Karen, Diego, Carina, Daija, Jenny
• Team 9—Elsie, Kiara, Denice, Chiso, Nayeli, Chyna
Interpret this graph
Explain to your neighbor the five fingers of
evolution
How can you explain bed bug evolution?
Stamps
• A2—bed bug comic with academic terms
• A2—guppy comic + questions answered
• A2 sickle 8 questions
• A3—mathematical modeling in computer lab—3 graphs and
interpretations
2 games—Class Dojo + Mastery Checklist
Answer in complete thoughts!
1. What do the red and blue dots represent in this simulation? What does the coin represent?
2. What does "allele frequency" means? How are allele frequencies related to evolution?
3. What are the "selective forces" in this simulation (the forces changing the allele
frequencies)?
4. What was the general trend you observed for Allele A over the three generations (did it
increase or decrease)? What was the general trend for Allele S over time? Was your
hypothesis supported?
5. Do you anticipate that the trends in question 4 will continue for many generations? Why or
why not?
6. Since few people with sickle cell anemia (SS) are likely to survive to have children of their
own, why hasn’t the mutant allele (S) been eliminated? (Hint: what is the benefit of keeping it
in the population?)
7. Why is the frequency of the sickle cell allele so much lower in the United States than in
Africa?
8. Scientists are working on a vaccine against malaria. What impact might the vaccine have in
the long run on the frequency of the sickle cell allele in Africa? (Would it increase or
decrease? Why?)
Take out dojo code and log in to change
monster
In the computer lab
Genetic drift simulation
• 3 graphs and explanations in notebook
The evolution of __________population
• Using your pics explain the evolution of your pop
• Calculate allele frequencies before and after
• Identify which of the five fingers of evolution occurred in your
population
Thanks to Ale for sending me the newly
discovered species in 2013
Bottle Neck
• An example of a bottleneck:
Northern elephant seals have reduced genetic variation
probably because of a population bottleneck humans
inflicted on them in the 1890s. Hunting reduced their
population size to as few as 20 individuals at the end of the
19th century.
• Their population has since rebounded to over 30,000—but
their genes still carry the marks of this bottleneck: they
have much less genetic variation than a population of
southern elephant seals that was not so intensely hunted.
•Why is losing variation a
problem for a population?
Founder effect
• A founder effect occurs when a new colony is started by a few
members of the original population. This small population size
means that the colony may have:
• reduced genetic variation from the original population.
• a non-random sample of the genes in the original population.
• For example, the Afrikaner population of Dutch settlers in
South Africa is descended mainly from a few colonists. Today,
the Afrikaner population has an unusually high frequency of the
gene that causes Huntington’s disease, because those original
Dutch colonists just happened to carry that gene with unusually
high frequency. This effect is easy to recognize in genetic
diseases, but of course, the frequencies of all sorts of genes are
affected by founder events.
Activity: Genetic Drift on Two Islands
1)What do you know about
sickle cell?
2) What is the allele
frequency of dominant eye
ALLELE in period 4? Show
work. Round to nearest
hundreths
Get stamp and then look at
AP plaques
Update your table of
contents
Announcements
•Keep photos of species with variation—
in computer lab Sep 30/Oct 1
•1.A.3 due Friday (period 4), Thurs
(period 1)
•Need power school log in? See me
FLT
•Using manipulatives I will
demonstrate the change in
alleles for sickle cell using
video, worksheet, and notes
Video
Genetics and sickle cell
Genotype
RR
rr
Rr
Phenotype
_____________
_____________
_____________
•Why does the sickle allele persist in the US?
Sickle Cell Allele Demo
•Red dots (recessive)—sickle cell
allele
•Green dots (dominant)—no sickle
•Need coin
Calculate individual and allele
frequency before and after 3
generations.
Procedure:
1) Together with your lab partners, obtain bag—this is your gene pool
• Start with 10 of each allele
2) Simulate fertilization by PICKING OUT two dots WITHOUT LOOKING.
Do this until bag is empty. Record
3) For every two dots that are chosen from the gene pool, another
person will FLIP A COIN to determine whether the homo’s live or die.
4) Using the table, the coin flipper tells the team which live and go
back into gene pool and which die (on table)
5) RECORD remaining alleles as a fraction
Total
Bag
individuals
Total Individuals F2 Total Individuals F3
AA
AS
SS
Nonsurviving
Alleles
F2
Number of A (blue) alleles surviving
Number of S (red) allele surviving
F3
Heads
Tails
AA Die from malaria Survive
malaria—can
reproduce
Live
AS Live
Die from sickle Survive sickle
cell anemia
cell—can
SS
reproduce
(blue)
Pick up worksheet
DNARNA
Protein
Codon Chart pg ---
On a separate sheet of paper
1) What have you learned in AP Biology so far?
2) How are you managing the workload/stress?
3) What suggestions do you have for the class?
Discuss
Watch super bugs
Photo project
•Take photos or make drawings
to illustrate the super bug
evolution
•Use bacterial replication info pg
333
Copy
Tablet Usage form
1) I will not peel off the plastic
2) I will only go on appropriate sites
3) I will leave the tablets in the room
4) I will not download or install anything on the tablet
Level 1
• Darwin question answer D
Structure of assessment day
• All students take level 1 as a practice test. Self grade.
Record score
• If you have 4 items on mastery list show Ms. Morris, put
your backpack and personal items along the back board.
Come to Tables 6-9 with a pen/pencil, reading guide, and
chepo ONLY
• Take level 2 and 3 silently. Turn in.
• If you are not assessing sit at tables 1-5. Not allowed to
cross the border.
A-2 Mingle
A2_Examples of Evolution
Should we use antibacterial soap?
• Bacteria, relative to humans, have very short generation times. A generation
time is the time it takes to go from one generation to the next. For example, in
humans, it takes on average about 20 years to go from the birth of a child to
the birth of that child’s child. Therefore, the generation time for humans is
approximately 20 years. Contrast this with the average bacterial generation
time of hours or even minutes! Under favorable conditions, a single bacterial
cell will very quickly reproduce into a colony containing many generations of its
offspring and their offspring. These colonies can have so many individual cells
that, within hours or days, it will be large enough to see with the naked eye.
Organisms with fast generation times, like bacteria, have the capacity for very
rapid adaptation to a changing environment. Since evolutionary change occurs
across generations, organisms with fast generation times (like bacteria) can
evolve much faster than organisms with slow generation times (like humans).
Some bacteria species can go through thousands of generations in a single year.
• Bacterial populations are also very high in numbers and are quite genetically
variable. Mutations are the primary source of genetic variation. Mutations
(accidents in DNA replication) are rare events. In bacteria, a mutation at a
particular gene occurs on average once in about every 10,000,000 cell divisions.
Since bacteria are so numerous and divide so often, even these rare events
actually occur quite often. As an example, E. coli cells in a human colon divide 2
x 1010 times every day. That means that every day in an E. coli population,
approximately 2000 cells will have a mutation at a particular gene5 . So, even
though mutations are rare events, they occur often enough in bacterial
populations to create a lot of genetic variation within populations.
• Mutation is not the only way that a bacterium can acquire a
resistance gene. Bacteria have three other methods of acquiring
genes that sexual organisms (like us) do not have. Bacteria can pick up
pieces of DNA (containing genes) from their environment
(transformation), they can obtain a gene from another bacterium
(conjugation), and genes can also be transferred to a bacterium by a
virus (transduction). So, even if a resistance gene does not occur
through mutation, it can be acquired through one of these methods.
• To summarize, bacterial populations evolve resistance to antibiotics
so quickly because of their fast generation times, large population
sizes, and unique methods of gene acquisition. These are some of
the reasons that bacteria have been so evolutionarily successful.
So what happens if a bacterial cell has a mutation that allows it
to resist the effect of an antibiotic? If that bacterium is in the
presence of the antibiotic, then it will have an advantage: the
drug will not kill it! It will be able to reproduce, while the
susceptible bacteria (which are inhibited or killed by the
antibiotic) will not. In the presence of the antibiotic, the
resistant mutant has a selective (reproductive) advantage
over normal cells3.
Originally, most or all bacteria in the population were
susceptible to the antibiotic4 . Over many generations, the
resistant type will make up a greater and greater percentage of
the population. Eventually, most or all of the individuals in the
bacterial population will be resistant to the antibiotic. The
population has evolved resistance due to natural selection by
antibiotics: the genetic structure of the population has
changed, from susceptible to the antibiotic to resistant to the
antibiotic.
Can you explain how natural selection is
acting on this population?
This next case study
is what you will
discuss during your
mingle
You are infected with a bacterial disease. Your sister had this same illness
last week, and took a full cycle of antibiotics. She quickly became better. You
started taking the same antibiotic,
but they had no effect. In fact, you had to return to the doctor after a week,
because you did not feel better. What has happened? Why did you remain
sick after taking antibiotics,
while your sister quickly recovered? There are three possible hypotheses:
A) you developed a tolerance for the antibiotic (i.e. you experienced a nongenetic change that made you less sensitive to the effects of the antibiotic).
B) the bacteria infecting you developed a tolerance for the antibiotic (i.e.
individual bacteria experienced a non-genetic change that made them less
sensitive to the effects of the antibiotic).
C) the bacteria infecting you evolved to be resistant to the antibiotic (i.e. a
genetic mutation for resistance occurred in a bacterial cell, it had a
reproductive advantage and increased in the population).
a) Which hypothesis (A, B, or C) do you think is most likely?
_________________
b) Explain why you chose this one.
• When you first visited your doctor, she told you that she
is conducting research on antibiotics, and asked you to be
a part of the study. You agree.
• As part of the study, you go to the doctor every day and
let her take a new sample from your infection, which she
then conducts tests on.
• She discovered that on the first day, your bacteria were
susceptible to the antibiotic (i.e. the bacteria were killed
by the antibiotic).
• She then prescribed the antibiotic to you, which you
immediately began taking.
• Later in the week, the bacteria from your infection were
found to be resistant to the antibiotic (i.e. the bacteria
were not killed by the antibiotic).
a) This result rules out which of the three hypotheses (A, B,
or C)? ______________
b) Why does this result rule out this particular hypothesis?
Another result from the study is that initially, all the bacteria
were susceptible to the antibiotic, but by the third day, some of
the bacteria were resistant to the antibiotic. With each passing
day, more of the bacteria were resistant, until finally all of the
bacteria were resistant.
a) Does this result support either (or both) of the remaining
hypotheses? ________
b) Does it allow you to rule out either of them?
______________
c) Explain your answers to a) and b).
• Your doctor performs a DNA analysis of the bacteria causing your infection, and discovers that the
resistant bacteria differ from the susceptible bacteria by one gene: the gene that encodes the
protein on the bacterial cell that is the “target” of the antibiotic (the target site is the place in the
bacterial cell where the antibiotic binds and does its dirty work).
• The resistant bacteria have an altered form of this target site, with the result that the antibiotic is
unable to bind to the target site, and thus is unable kill the bacterium.
a) How did the resistant bacteria come to be different genetically from their susceptible ancestors?
b) Which hypothesis does this result support? _______________
c) Why does this result support this particular hypothesis?
Given all of the above evidence, which hypothesis (A, B,
or C) do you think is most likely correct? Explain.
Watch--The Evolution of
Antibiotic Resistance
• http://www.pbs.org/wgbh/evolution/educators/lessons/lesson6/act1
.html
Natural selection in action—show off your diagram
Wed
Warm Up
1. Draw a gene pool.
2. How do brine shrimp show natural selection?
3. What did you learn about the nature of science from your
experiment?
4. Reasoning is like closing arguments in a court case. Explain.
• Pick up mini-poster + other things that have been graded
ANNOUNCEMENTS--Grades this Friday, Back-to-School tonight
To redo
•Staple new discussion over old
•I must be able to see the old discussion
•Please write redo on your new discussion
AP Biology Game
Moves
 1 space—A1 ppt and video notes (expired)
 1 space—90% or higher on Brine Shrimp poster
 1 space—80% or higher on A1_Level 2
 1 space--80% or higher on A1_Level 3
 1 space—A2 notes (expired Thurs)
5 spaces=A on 5 week report card
FLT
•I can extrapolate the allele
frequencies for a population
undergoing selection and genetic
drift using notes and activity
Part D—Heterozygous Advantage (Homo dom—may die of
maleria (flip coin; homo recessive—die of sickle cell)
• Initial Class Frequencies GG____ Gg __ gg___
• My initial genotype ___
• F1____
• F2_____
• F3_____
• F4_____
• F5______
Final Class Frequencies
Your turn—how do you show if Hardy is met
or if evolution occurred
• Scenario 1—Selection
• Scenario 2—Genetic Drift
For each scenario
-explain how you will set up the class (ex students
start with 4 alleles—all hetero and then__________
-how many generations in your game
-what you expect to happen to the allele frequencies
Level 1 Answers
1) A
2) E
3) E
4) C
5) C
q2=40/1000
q2=0.04
q=.2
Warm Up
• Pick up A2 Mastery Checklist and Hardy Problem Set
• A2 notes and video EXPIRES THURSDAY
• Work on Hardy Set—key in 3 places in the room
• Assessments and grades this week—look at my office hours
for this week
FLT
•I can communicate my
findings to my peers
through the mini-poster
presentation