day 12 february 28th chapter 7 and 8
TRANSCRIPT
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Day 12 February 28th Chapters 7
and 8
Second exam, oh no!
Chance for retakes
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Retake of Second Exam
Check your score on Springboard
If you want to retake
You have to have a study session with a tutor oryour lab TA. You must get your study guide signed
by them, turn it in to me, and then you will get a
password to retake the exam.
Must be done by spring break
Youll get an average of the two grades.
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How likely is it that you will retake
your exam?1. Very likely
2. Somewhat likely
3. Not likely4. No way, Jose!
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7.11 Multi-gene TraitsHow are continuously varying traitssuch as height influenced by genes?
Old wives tales suggest a couple of ways for predicting height:
if the baby is a boy, they say to add five inches to the mothers
height and average that with the fathers height. Or if it is a
girl, subtract five inches from the fathers height and average
that with the mothers height. Alternatively, the lore says to
just take the childs height at two years and double it.
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Polygenic Trait
A trait that is influenced by many differentgenes
Mi
nd-blowi
nglycomplicated!!!
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Additive Effects
what happens when the effects of allelesfrom multiple genes all contribute to the
ultimate phenotype
The Tall Gene
hormones and
bone length
and growthfactors oh
my!
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Why might computer nerds
be more likely to haveautistic children?
Autism involves 10 or 20 different genes!
Unusual abilities of perception, analytical
skills, and focus. This ideacalled the geek
theory of autism
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7.12 Pleiotropy: How can one
gene influence multiple traits?
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What isthebenefit of
almosthavingsickle cell
disease?
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The SRY Gene
Sex-determining Region on the Y-chromosome
Causes fetal gonads to develop as testesshortly after fertilization.
Following the gonads secretion oftestosterone, other developmental changesalso occur.
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7.13 Why are more men
than women color-blind?
Sex-linked traits differ in theirpatterns of expression in males
and females.
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Colorblindness
1. I am a non-colorblind male
2. I am a colorblind male
3. I am a non-colorblind female4. I am a colorblind female.
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If a man is color-blind, did heinherit this condition from his
mother, his father, or bothparents?
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men only get
one chance to
inher
it thenormal version
of the gene
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If a male is colorblind, from
whom did he inherit thecondition?
1. Mother2. Father
3. Grandfather
4. Aunt
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If a male is colorblind, from
whom did he inherit thecondition?
1. Mother2. Father
3. Grandfather
4. Aunt
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In which example below will there
be a chance of a daughter beingcolorblind?
1. A male who is colorblind marries a female
who is a carrier for colorblindness.
2. A male who has normal vision marries afemale who is a carrier for colorblindness.
3. A male who has normal vision marries afemale who is colorblind.
4. Choices 2 and 3 are correct.
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In which example below will there
be a chance of a daughter beingcolorblind?
1. A male who is colorblind marries a female
who is a carrier for colorblindness.
2. A male who has normal vision marries afemale who is a carrier for colorblindness.
3. A male who has normal vision marries afemale who is colorblind.
4. Choices 2 and 3 are correct.
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Chapter 8: Evolution and Natural Selection
Darwins dangerous idea: evolution by natural selection
Lectures by Mark Manteuffel, St. Louis Community College ; Clicker Questions by Kristen Curran, University ofWisconsin-Whitewater
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I feel like I know what the word
evolution means.
1. Very sure.
2. Slightly sure
3. Clueless4. I know that I dont know what the scientific
meaning of the word is.
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Evolution in Action
8.1 We can see evolution occurright before us. Therefore,evolution is a scientific process.
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Could you breed fruitflies who could livelonger than 20 hours
on average?
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Populations
are studi
ed
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When these eggs hatch, do you think theflies in this new generation will live longerthan 20 hours without food?
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Make a prediction:A population of fruit flies was starved until80% of the flies were dead. The remaining flies were fed andoffspring were produced. What do you expect to see in the nextgeneration if you repeat the starvation experiment?
1. More flies will be alive after 20 hours.
2. Fewer flies will be alive after 20 hours.
3. Fruit flies fed after 80% of the population is deadwill lay more eggs.
4. No change in the average number of fruit fliesthat were alive after 20 hours.
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Make a prediction:A population of fruit flies was starved until80% of the flies were dead. The remaining flies were fed andoffspring were produced. What do you expect to see in the nextgeneration if you repeat the starvation experiment?
1. More flies will be alive after 20 hours.
2. Fewer flies will be alive after 20 hours.
3. Fruit flies fed after 80% of the population is deadwill lay more eggs.
4. No change in the average number of fruit fliesthat were alive after 20 hours.
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After 60 generations the average starvation resistanceof fruit flies was 160 hours! What has happened to
this population of fruit flies?
1. They are genetically identical to theoriginal population.
2. The are genetically different from theoriginal population.
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After 60 generations the average starvation resistanceof fruit flies was 160 hours! What has happened to
this population of fruit flies?
1. They are genetically identical to theoriginal population.
2. The are genetically different from theoriginal population.
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What happened?
Evolution
a genetic change in the population
Natural selection the consequence of certain individual organisms in
a population being born with characteristics thatenable them to survive better and reproduce more
than the offspring of other individuals in thepopulation
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Does evolution occur?
The answer is an unambiguous: YES.
We can watch it happen in the labwhenever we want.
Recall from our discussion of the scientific method
that for an experiments results to be valid, they
must be reproducible.
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Experiments in Evolution
Dogs?
Rabbits?
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In Nature -
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Why are camels a successful species?
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Evolution
How does evolution occur?
What types of changes can evolutioncause in a population?
Five primary lines of evidence
Evolution by natural selection
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Darwins Journey to an Idea
8.2 Before Darwin, most peoplebelieved that all species had beencreated separately and wereunchanging.
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Button started the debate by suggesting the Earth
had to be at least 75,000 years old!
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Jean-Baptiste Lamarck
Biologist, early 1800s
Living species might change over time.
(Was wrong about the mechanism - he thought that change came about
through the use or disuse of features)
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Charles Lyell
Geologist
1830 book Principles of Geology Geological forces had shaped the earth and were
continuing to do so.
Gradual but constant change
This idea that the physical features of the earth were constantly changing would most
closely parallel Darwins idea that the living species of the earth, too, were gradually
but constantlychanging.
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We know the Earth is constantly
changing
Fossils of shells have been found high in theAndes Mountains
Forest fires wipe out entire species of plants andanimals.
Rivers flow, and carve out rock, creating twodistinct shores, where different species live.
Lakes dry up, killing all marine life inside.
Pollution and Toxic spills kill organisms. Volcanoes.
Humans are changing the earth.
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In the 1790s, Georges Cuvier began to explore the bottoms
of coal and slate mines and found fossils
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Why were fossils such a problem for
people at that time?
This was highly troubling for people at the
time.
http://www.bspcn.com/2009/04/03/11-extinct-animals-that-have-been-photographed-alive/
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Extinction
five mass extinctions on earth, and four in thelast 3.5 billion years - many species havedisappeared in a relatively short period of
geological time. The "Great Dying" about 250 million years ago,
which is estimated to have killed 90% of speciesexisting at the time.
Most extinctions have occurred naturally, withouthuman intervention: it is estimated that 99.9% ofall species that have ever existed are now extinct.