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Transcript
Introductory Questions #1-(review)
1)
2)
3)
4)
5)
6)
7)
8)
Briefly explain the differences between Transformation,
Conjugation, and Transduction. How are these three processes
the same? (pgs. 348-349)
How is an “F plasmid” different from an “R plasmid”?
How are repressible operons different from inducible operons?
Give an example of each.
What is the difference between an operator and a promoter?
Name three example of a virus that has DNA as its genetic
material and three examples of Viruses with RNA as its genetic
material. (See the table in text)
Briefly explain what a vaccine is and what it does.
Why are transposons called “jumping genes”? What purpose do
the insertion sequences play?
What is the difference between an oncogene and a tumor
repressor gene?
Inactive Repressor-Lactose Present
http://highered.mcgraw-hill.com/sites/0072437316/student_view0/chapter18/animations.html
Examples of Common Viruses
DNA
Herpesvirus
Poxvirus
Papovirus (warts)
RNA
Ebola
Infuenza
HIV
Measels, Mumps
Rabies
West Nile
Vaccines-Pg. 343
•
•
•
•
Harmless variants of the pathogen
Stimulate the immune system-produce antibodies
Smallpox has thought to be eradicated (polio)
Rubella, mumps, hepatitis B, other viral diseases
Review of Concepts (Ch. 1-20)
1) Give three important properties of water
2) How is an amino acid different from a nucleic acid?
3) Explain how a carbohydrate is different from a lipid?
Give three examples of each.
4) How is glycolysis different from the Kreb Cycle?
5) Give three differences between Mitosis and Meiosis
6) Why is cholesterol an important part of a membrane?
7) How can you tell if genes are linked?
8) Name three aneuploidy conditions and three
Autosomal recessive disorders we discussed.
Review of Concepts (Ch. 1-20)
9) Put these scientists in the proper Historical sequence
according to their key discoveries. Generate a
timeline labeling each person on it with the date.
Sumner
Meselson & Stahl
Morgan
Peter Mitchell
Garrod
Hershey & Chase
Griffith
Singer & Nicholson
Meissner
Watson & Crick
Frye & Edidin
Avery, Macloed, & McCarty
McClintock
Timeline for Key Figures & Research
•
•
•
•
•
•
•
•
•
•
•
•
Meissner
(1868)
Garrod
(1908)
Morgan
(1910)
Sumner
(1926)
Griffith
(1928)
Avery, McCloed, & Macarty (1944)
Hershey & Chase
(1952)
Watson & Crick
(1953)
Meselson & Stahl
(1958)
Peter Mitchell
(1961)
Frye & Edidin
(1970)
Singer & Nicholson
(1972)
Key Enzymes to Remember
Can you determine the process each of the enzymes below
are involved with and what it specifically does?
Eco R1, Hind III, and BAM I
Telomerase
DNA Polymerase (I,III)
Aminoacetyl-tRNA synthetase
Cyclin dependent kinase (Cdk’s)
Dehydrogenase (name two)
ATP synthase
Pyruvate kinase
Hexokinase
Helicase
Lactase
SSBP’s
DNA ligase
Aldolase
Sucrase
MPF
Isomerase
Next Unit:
Evolution & History of Life- Chapters: 22-26
Chapter 22: Darwinian View of Evolution
Chapter 23: Microevolution &Allele frequency
changes in Populations
Chapter 24: Macroevolution (Speciation)
Chapter 25 & 26: Mapping out the History of Life
through systematics & Phylogenic relationships.
Introductory Questions #2
1) Why is evolution such a controversial subject?
2) Name the key founders (original people) for the idea
evolution.
3) Name four major pieces of evidence that Darwin
considered in formulating his theory of natural selection.
4) Name three people that influenced Darwin’s thinking as
he developed his theory.
5) Name the four key observations Darwin made.
6) Why is fossil evidence considered the “most direct”
evidence for evolution? Approximately, how many fossil
species have been discovered?
7) What are the three methods for generating a date of a
fossil?
Chapter 22: Darwinian Evolution
(The Beginning)
Charles Darwin:
-Born in England
-Medical School
-Clergyman
-Naturalist (botany)
-Explorer (HMS Beagle)
http://www.pbs.org/wgbh/nova/id/program.html
Descent with Modification (Evolution)
Evolution:
the change over time of the
genetic composition of populations
Natural selection:
populations of organisms can
change over the generations if
individuals having certain
heritable traits leave more
offspring than others (differential
reproductive success)
Evolutionary adaptations:
a prevalence of inherited
characteristics that enhance
organisms’ survival and
reproduction
November 24, 1859
Introductory Questions #2
1) Why is evolution such a controversial subject?
2) Name the key founders (original people) for the idea
evolution.
3) Name four major pieces of evidence that Darwin
considered in formulating his theory of natural selection.
4) Name three people that influenced Darwin’s thinking as
he developed his theory.
5) Name the four key observations Darwin made.
6) Why is fossil evidence considered the “most direct”
evidence for evolution? Approximately, how many fossil
species have been discovered?
7) What are the three methods for generating a date of a
fossil?
Major Issues & Questions about Evolution
• Our Concept of time is obscure: putting into
perspective and grasping the significance of
long periods of time such as 100 yrs?
1000yrs? 10,000yrs? Or even a million years.
• The most difficult concept that Darwin
proposed was that all living things are
related by a common ancestor.
• How would respond to this question?
– When studying life do you include man with all
living things or do you separate man?
Evolutionary History
•
•
•
•
•
Linnaeus: taxonomy (binomial Nomenclature)
Hutton: gradualism
Lamarck: Use & disuse (acquired Charact)
Malthus: populations & resources
Cuvier: Paleontology (fossils)
•
•
•
•
Lyell: uniformitarianism
Darwin: Natural selection
Mendel: inheritance
Wallace: natural selection
Historical Perspectives on Evolution
• Aristotle
• Linnaeus
• Cuvier
•
•
•
•
Charles Lyell
Hutton
Erasmus Darwin
Lamarck
•
•
•
•
Henslow
FitzRoy
Malthus
Wallace
Species are “fixed” & unchanging
Founder of taxonomy (binomial nomenclature)
Began the study of fossils (Paleontology)
Catastrophism
Uniformitarianism-same process occur today
Gradualism
Environment changes causes life to evolve
Law of use & disuse, inheritance of acquired
characteristics
Darwin’s mentor at Cambridge (Botanist)
Captain of HMS Beagle
Populations struggle for resources (competition)
formulated same theory of natural selection
Influences on Darwin’s Theory
• Lyell (Geologist)
– Earth was ancient & everchanging
Influences on Darwin’s Theory
• Malthus
(Economist)
–“Survival of the
Fittest”
• Political &
Philosophical
Renaissance
Video Clip
Observations made by Darwin
•
•
•
•
•
•
Variations exist in the population (heritable)
Reproduce Exponentially (if all are successful)
Populations tend to be stable
Resources are (become) limited
Differential Reproductive success (selection)
Artificial selection (breeding) modifies adaptations
Galapagos Islands
• Noted subtle differences in finches
& tortoises, by island &
compared to mainland
Adaptions to Environment
Phylogenetic Tree of Darwin’s Finches
Common Ground Finch
Examples of Descent with Modification
Based on Fossil Evidence
Major pieces of Evidence for Evolution
•
•
•
•
Biogeographical Distribution
Comparative Anatomy (homologous structures & vestigial organs)
Comparative Embryology
Fossils
Post Darwin: “Neo Darwinism” also called synthetic theory
• Molecular Genetics: DNA/Amino acid Sequencing
• Chromosomal Changes
• Mutations
Evolution evidence:
Biogeography
• Geographical
distribution of species
• Examples:
Islands vs. Mainland
Australia
Continents
These organisms evolved independently of each other in
similar environments
Evolution Evidence: Comparative Anatomy
• Homologous
structures (homology)
• Descent from a
common ancestor
• Vestigial organs
Ex: whale/snake
hindlimbs; wings on
flightless birds
• Convergent Evolution due to similar
niches-same structures form w/same
purposes
Similar
characteristics
formed from similar
environments with
different original
structures.
Structures are used for
a similar function
**Similar structure different origin
Evolution Evidence: Comparative Embryology
• Pharyngeal pouches,
‘tails’ as embryos
Fossil Evidence
Fossils: remains and traces left behind by organisms
-most direct evidence for evolution
-provides a record of ancient organisms that have existed
-able to generate a timeline
-observe the presence of vestigial structures
-ancestral descent and lineages can be generated
-more aquatic fossils vs. terrestrial have been found
Types of Fossils: imprints, hair, nails, tissue, and other
remains
Locations: sedimentary rock, ice, amber, tar, quicksand,
petrification
Evolution Evidence: The Fossil Record
• Succession of forms
over time
• Transitional links
• Vertebrate descent
Dating Fossils
• Location within the rock strata (use index
fossil)
• Radioactive isotopes (half-life)
–
–
–
–
K40 half life is 1.3 billion years argon
U235 half life is 704 million years → lead
U238 half life is 4.5 billion
→ lead
C14 half life is 5730 years
 nitrogen
Extinct Whale w/ small hind limbs
Evolution of the Horse
Issues/Arguments with Fossil Evidence
•
•
•
•
Record is Incomplete
Transitional fossils are lacking
Dating techniques are not very accurate (wide ranges)
Fossils are difficult to find
– Conditions must be perfect to form & remain intact
• Provides evidence of species that existed but are now
extinct (ex. dinosaurs)
• What if fossils were never found?
Evolution Evidence of Today
& Molecular Biology
• Similarities in DNA,
proteins, genes, and
gene products
• Common genetic code
Human & Chimp Comparison of Chromosome #2
http://www.teachersdomain.org/special/evol07-ex/
Human Chromosome #2
Molecular evidence for common Ancestry
Introductory Questions #3
1) What is meant by homoplastic features?
2) Organisms that are from separate ancestries adapt to their
environments similarly from similar structures. This is
an example of
.
3) How many vestigial structures have been observed in
humans. Name three of them.
4) Why is biogeography (distribution of species) important
evidence for evolution?
5) Why is the chimpanzee considered to be the closest
living relative of humans?
6) How is a phylogenetic tree generated and what sort of
information does it provide?
Key Points to Remember
• A population evolves, not an individual organism
• Natural Selection occurs through interactions between individuals
• Variations in a population are heritable that are not “acquired in
their lifetime”
• Natural selection is the “mechanism” of evolution
• The accumulation of small gradual changes over long periods of
time results in larger changes (adaptations)
• A new species emerges with slightly different characteristics usually
because of being isolated. (Galapagos Islands)
• How and why organisms are able to transmit heritable traits to the
next generation was not explained by Darwin.
• Evolution can only modify existing structures.
Final words…...
• “Absence of evidence
is not evidence of
absence.”
Chapter 23-Microevolution
Population genetics
• Population:
a localized group of individuals
belonging to the same species
• Species:
a group of populations whose
individuals have the potential to
interbreed and produce fertile offspring
• Gene pool:
the total aggregate of genes in a
population at any one time
• Population genetics:
the study of genetic changes in
populations
• Modern synthesis/neo-Darwinism
• “Individuals are selected, but populations
evolve.”
Hardy-Weinberg Principle
•
•
•
•
•
Model proposed in 1908
Represents an ideal situation
Seldom occurs in nature
Mathematical model is used to compare populations
Allows biologists to calculate allele frequencies in a
population
• Serves as a model for the genetic structure of a
non-evolving population (equilibrium)
Represents “genetic equilibrium”
If the allele frequencies deviate from the predicted values of HW then
the population is said to be evolving.
Hardy-Weinberg Theorem
5 conditions for Equilibrium
-Very large population size
- No migration
- No net mutations
- Random mating
- No natural selection
**when all these are met then
a population is not
evolving
Hardy-Weinberg Equation
• p=frequency of one allele (A);
•
•
•
•
•
q=frequency of the other allele (a)
p+q=1.0
(p=1-q & q=1-p)
P2=frequency of AA genotype
2pq=frequency of Aa
q2=frequency of aa genotype;
p2 + 2pq + q2 = 1.0
Solving & Analyzing HW Principle
•
Problem: If you had 90 individuals that possessed the recessive
condition in a population of 1000 individuals, determine the
frequency of dominant and recessive alleles present in the
population as well as the genotypic and phenotypic frequencies.
(1) Always start with the # of homozygous recessive alleles
- aa = 90 and q2 = 90/1000 which is 0.09
- a = square root of 0.09 which is 0.3
- A = (1 – 0.3) which is 0.7
- AA = (0.7) 2 which is 0.49
- Aa = ???
**Remember that p2 + 2pq + q2 = 1
(AA)
(Aa)
(aa)
Microevolution
• Involves small or minor changes in the allele
frequencies within a population
• Five processes have been identified:
–
–
–
–
–
Nonrandom mating (inbreeding & assortative mating)
Gene flow
(migration between populations)
Genetic drift
(bottleneck effect)
Mutations
(unpredictable change in DNA)
Natural selection
(differential reproduction)
**certain alleles are favored over others in nature
Microevolution
A change in the gene pool
of a population over a
succession of
generations
Genetic drift: changes
in the gene pool of a
small population due to
chance (usually
reduces genetic
variability)
Molecular Clock-Pg 385
• Used to estimate the time of divergence between two
closely related groups when their common ancestor
could have been present.
• Mutations tend to occur at a steady uniform rate over
millions of years for closely related species.
• These alterations in the DNA sequence used with
geological data
• Allows scientists to reconstruct the evolutionary
history of a group and describe its phylogeny
• A single molecular clock for all genes and all species
cannot be established. (Why?)