What’s Left in LB145? Last Class: – Course Evaluations – Take up Exam – Begin Evolution Unit Today: – Finish Evolution Unit Tuesday Apr 23 rd : – Bonus survey – Traditional review (?) Thursday April 25 th : – Question-based review (?) Don’t Forget… Friday April 19 th : View Exams 1, 2, 3 in C4 from 1-3pm. OR Office hours. Weds/Thurs April 24 th /25 th : Lab Projects Due. Friday April 26 th : 3-5pm in C-3 Last-Gasp Tutorial
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What’s Left in LB145? Last Class: Course Evaluations Take up Exam Begin Evolution Unit Today:
What’s Left in LB145? Last Class: Course Evaluations Take up Exam Begin Evolution Unit Today: Finish Evolution Unit Tuesday Apr 23 rd : Bonus survey Traditional review (?) Thursday April 25 th : Question -based review (?). Don’t Forget… Friday April 19 th : - PowerPoint PPT Presentation
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What’s Left in LB145?Last Class:
– Course Evaluations– Take up Exam– Begin Evolution Unit
Today:– Finish Evolution Unit
Tuesday Apr 23rd:– Bonus survey– Traditional review (?)
Thursday April 25th:– Question-based review (?)
Don’t Forget…
Friday April 19th:View Exams 1, 2, 3 in C4 from 1-3pm. OR Office hours.
Weds/Thurs April 24th/25th:Lab Projects Due.
Friday April 26th: 3-5pm in C-3Last-Gasp Tutorial (email me to reserve a place)
Evolution
Write it Down:What is evolution?
EvolutionWrite it Down:Why is evolution controversial?
Social-Political-Religious Pressures
Source: Gallop Poll 2007
Why is Evolution treated differently from other theories?
1. Social-Political-Religious Pressures
2. It’s presented as belief construct
3. It is complicated and is not often taught/learned very well
Other Academic TheoriesBig Bang Theory, Cell Theory, Germ Theory, Molecular Theory, the Kinetic Theory of Gasses, Molecular Orbital Theory, Variance Bond Theory, Transition State Theory, Marchs Theory, Debye-Huckel Theory, Thermodynamic Theory of Polymer Elasticity, Density Functional Theory, Baeyer Strain Theory, Climate Change Theory, Macroeconomic Theory, Microeconomic Theory, Constructivist Theory, Critical Pedagogy Theory, Multiple Intelligence Theory, Circuit Theory, Control Theory, Systems Theory, Film Theory, Theory of Plate Tectonics, Literary Theory, Approximation Theory, Coding Theory, Intersection Theory, Matrix Theory, Model Theory, Ring Theory, Music Theory, Proof Theory, Theory of Truth, Acoustic Theory, Atomic Theory, Perturbation Theory, Theory of Relativity, Theory of the Mind, Cognitive Dissonance Theory, Attachment Theory, Theory of Self Fulfilling Prophecy, Sociological Theory, Critical Theory, Extreme Value Theory, Performance Theory….
Evolution
Write it Down:How would you explain evolution to a non-scientist?
Evolution through natural selection…
Mouse Fur Color
c(tyr)
Tyrp1Tyrp2p
MC1R protein is stimulated and facilitates cAMP production.cAMP is used to regulate gene expression.
Biological evolution is change in the properties of populations of organisms that transcend the lifetime of a single individual. Biological evolution may be slight or substantial; it embraces everything from slight changes in the proportion of different alleles within a population to the successive alterations that led from the earliest protoorganism to snails, bees, giraffes, and dandelions.
Douglas J. Futuyma
Evolution is…… the process by which different kinds of living organisms developed and diversified from earlier forms during the history of the earth.
Patterns of Relatedness
Evolution – a populations definition
“Evolution can be precisely defined as any change in the frequency of alleles within a gene pool from one generation to the next”
Helena Curtis and N. Sue Barnes
Darwin’s Evolution
• Had no knowledge of genetics.• Connected evolution with ecology.
Ecology and Evolution• Beak size in Galapagos Finches
Darwin’s Evolution
?
Darwin’s Finches
Trait Evolution
• The evolution of traits relates to the evolution of species.
Evolution facilitates speciation.
How does speciation occur?
Speciation occurs…
• When two populations become different enough from each other.
Species Concepts• Biological Species – a set of interbreeding populations.• Genetic Species – based on similarity of DNA.• Ecological Species – a set of organisms that occupy the
same niche.• Phylogenetic Species – a group of organisms that share an
ancestor and maintains its integrity through time and space.
One way to look at it:One species can be differentiated from another based on a differing set of traits.
Traits: a functional unit of evolution
• If you can describe how a trait evolved and why a trait is selected for then you can describe evolution.
Evolution of Traits
One More Case:
• Color Vision Evolution in Monkeys
What is colorblindness?
Reduced ability to interpret light as color.
1 in 12 males are colorblind.< 1 in 100 females are colorblind.
Are You Colorblind?
A) No (Female)
B) Yes (Female)
C) No (Male)
D) Yes, very (Male)
E) Yes, somewhat (Male)
Agree or Disagree: It is nearly always advantageous to have trichromatic vision.
(i.e. compared to dichromatic vision)
A. Strongly AgreeB. AgreeC. NeutralD. DisagreeE. Strongly Disagree
Agree or Disagree: Some humans probably have tetrachromatic vision.
A. Strongly AgreeB. AgreeC. NeutralD. DisagreeE. Strongly Disagree
Do you think YOU have tetrachromatic vision?
A. Yes (female)B. No (female)C. I have no ideaD. Yes (male)E. No (male)
Monkeys of the World
NEW WORLDOLD WORLD
TRICHROMATS DICHROMATS
How Does Color Vision Work?Cell Biology:
How Does Color Vision Work?
Three types of Cone Cell
• Different kinds of opsin proteins embedded in the membrane of cone cells.
• Central Dogma of Molecular Biology:DNA RNA ProteinGenes code for…. proteinsProteins are responsible for
cell function
• To produce the signal for color vision, retinal must stimulate the opsin protein but this cannot occur while the retinal molecule is in its cis- formation.
Opsin
Ops
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3.2a
11-cis-retinal
• When 11-cis-retinal absorbs a photon (a basic unit of light), it changes from 11-cis-retinal to All-trans-retinal.
Ops
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3.2b
Opsin
11-cis-retinal
Ops
in Im
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mod
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Sci
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3.2c
Opsin
All-trans-retinal
• All-trans-retinal stimulates the opsin in the membrane of the cone cell.
• The cone cell sends a signal to the brain that is interpreted as colored light.
SIGNAL
Ops
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3.2d
Opsin
All-trans-retinal
The Role of OpsinsThere are three types of opsins:Short Wave Sensitive (SWS)Medium Wave Sensitive (MWS)Long Wave Sensitive (LWS)
An individual who produces only SWS and MWS opsin proteins will have dichromatic vision.
An individual who produces SWS, MWS and LWS opsin proteins will have trichromatic vision.
SWS MWS LWS
3.3
Cone Cell Response to Light
Image from www.answers.com/topic/photopsin
MWS Opsin vs. LWS Opsin
What’s the difference?
Location of Opsin Genes
The gene coding for the SWS opsin protein is located on chromosome #7.
The gene coding for the MWS and LWS opsins are located on the X-chromosome.
Chromosome #7M
Chromosome #7P
Chromosome X1
Chromosome X2
4.2
Origin of the LWS Opsin Gene
The LWS gene arose through gene duplication and gene mutation of the MWS gene on the X-chromosome.
GENE DUPLICATION
GENE MUTATION
Chromosome X
Chromosome X
Chromosome X
4.3
Gene Duplication4.4
Unequal Crossing Over(Meiosis, Prophase 1)
XMXP XMXPXMXP
Interphase S Prophase I …Telophase II
4.5
Origin of the LWS Opsin Gene
The LWS gene arose through gene duplication and gene mutation of the MWS gene on the X-chromosome.
GENE DUPLICATION
GENE MUTATION
Chromosome X
Chromosome X
Chromosome X
4.3
Chromatic Vision: Opsins
3D Visualization 2D Visualization
The opsin protein is composed of a string of amino acids. Each green dot in the 2D visualization represents one amino acid.
Gene MutationThe LWS opsin is a mutated copy of the MWS opsin. Knowing that most of the difference in spectral sensitivity comes from two differences in amino acid structure of these two opsins), what is the likely number of nucleotide mutations needed for successful mutation from a MWS opsin to a LWS opsin? Position 277: phenylalanine to tyrosinePosition 285: alanine to threonine
Amino Acid Possible CodonsAlanine GCU, GCC, GCA, GCG
Threonine ACU, ACC, ACA, ACG
Phenylalanine UUU, UUC
Tyrosine UAU, UAC
4.19
Can a primate with only TWO functional opsin genes (e.g. SWS & MWS) ever have
trichromatic vision?
A. Yes – definitelyB. Not sure, but possiblyC. No ideaD. Not sure, but probably notE. No – definitely not