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Precambrian
first appearance of hard-shelled animals, better preserved in the fossil record
protoplanetary disk
A rotating disk of gas and dust grains surrounding a newly formed star. Over time, can form protoplanets
formation of Earth
gravity outside of the sun caused matter to condense around the protoplanets
Late Hadean eon
Earth surface cooled quickly. 4-3.8 bya, heavy asteroid bombardment the steam and gases created atmosphere, still volanic
Gases around during late Hadean eon
ammonia, CO2, no free oxygen
First life
end of the Hadean eon, between 4.2 and 3.8 bya
time period: Precambrian supereon
4.6 bya- 543 mya
time period: Paleozoic era
543 mya - 250 mya
time period: Mesozoic era
250 mya- 65 mya
time period: Cenozoic era
65 mya to now
What is the Cenozoic era split into?
Paleogene, Neogene, Quaternary
Stromatolites
single cells, some of the first life to evolve, mats of cyanobacteria
Multicellular life
arose late in the Precambrian, 1 bya
Paleozoic era
first land plants and animals
Cambrian explosion
rapid diversification of most major animal groups marking the start of the Paleozoic era
Permain extinction
"the great dying", 96% of marine life, 70% of land animals went extinct, only known mass extinction of insects
Mesozoic Era
Age of reptiles, dramatic lowering of the number of animals, first mammals
K-Pg Extinction
Cretaceous-Paleogene extinction event 65 million years ago. Killed off the dinosaurs, possible caused by a meteor, made room for mammals to become dominant
Cenozoic era
age of mammals
Hadean eon
no oceans, no free oxygen, only hydrogen and helium gas, no protective atmosphere
Two characteristics of life
organization, replicates itself
Earth 3.8 bya
molten rock, no free oxygen and high energy
Four steps to life on early Earth
1. Abiotic synthesis of organic material
2. Formation of polymers
3. Forming protobionts
4. Origin of hereditary material
Miller-Urey Experiment
Experiment that found that organic molecules can form in a strongly reducing atmosphere.
Products after one week of the Miller-Urey experiment
amino acids, nucleotides, sugars, lipids, ATP
What is the importance of clay?
clay is rich in minerals like iron and zinc which can attract monomers leading to the formation of polymers
protobionts
collections of abiotically produced molecules surrounded by a membrane-like structure
protocells
precursor of a living cell that had a membrane-like structure and that maintained an internal chemistry different from that of its surroundings
RNA world
easily forms abiotically (more easily than DNA), can replicate itself, has hereditary information and has catalytic properties
Beginning of time
most people thought that life was created by a supernatural power
Tenants of the history of the theory of evolution
supreme being placed organism on Earth, the organisms were designed by the supreme being, species do not change
Anaximander
Greek philosopher who suggested that humans evolved from fish that had moved onto land, theory of common descent and transmutation of species
Carolus Linnaeus
founder of taxonomy, the branch of biology concerned with naming and classifying organisms, binomial nomenclature, hierarchical classification
James Hutton
father of modern geology, natural processes gradually shaped rock formations, first person to contradict the young Earth hypothesis
Gradualism
James Hutton's theory that evolution occurs slowly but steadily
Sedimentation
the action or process of forming or depositing sediment and being compressed to form stone
Adam Smith
Economist who was known for Laissez-faire economics, chaos governed by invisible hand and believed in the benefits of competition
Jean-Baptiste Lamarck
This man developed the first cohesive theory of evolution after his studies of biology, inheritance of acquired characteristics "use and disuse"
Thomas Malthus
Known for an essay about the Principle of Population, said human population can outgrow food supply; result will be war, famine, disease
Georges Cuvier
developed paleontology, the study of fossils and comparative anatomy, advocated for catastrophism
Catastrophism
A principle that states that geologic change occurs suddenly
Charles Lyell
effectively discredited the long-standing view that the earth's surface had been formed by short-lived events, his theory was uniformitarianism: same geological processes that are at work today slowly formed the earth's surface over a long time
Uniformitarianism
Charles Lyell's idea that geologic processes have not changed throughout Earth's history.
Charles Darwin
English natural scientist who formulated a theory of evolution by natural selection, species evolved from common ancestor
Alfred Russel Wallace
British naturalist who developed a hypothesis of natural selection similar to Darwin's
Gregor Mendel
Augustinian monk and botanist whose experiments in breeding garden peas led to his eventual recognition as founder of the science of genetics, discovered that traits are inherited by predictable laws
James Watson and Francis Crick
discovered the structure of DNA, means for heritable information to be stored and passed on
Darwin's hypothesis
there must be variation in the population, variation must lead to difference in reproductive success, variation must be transmitted to the next generation
Darwin's hypothesis: 5 parts
individuals vary, populations tend to overbred leading to survival struggles, survival of the fittest, survivors will reproduce, traits leading to better survival must be heritable
Grant and Grant
discover that better variation for a particular environment have higher survival rates, find this by studying the finches
1977
La Nina, extreme drought and population decline, withered vegetation, mostly large, hard seeds remain--larger beaked finches survive
1984/85
El Nino, wet, abundant vegetation, high concentration of small softer seeds--finches with small beaks survive
Grant and Grant II
also help to prove that survivors have more offspring and that the traits that are heritable (like beak size) are passed down to their offspring
Implications of Darwin's Theory
Earth must be old enough for evolution to occur, fossils would show the change with older rock having fewer modern fossils, the gradual small changes through time indicates that there should be intermediates
Is the Earth old enough for evolution to have occurred?
Yes, illustrated by depth of canyons and thickness of rock strata which can be dated back billions of years
"Missing Links"
intermediate fossils between groups of organisms that must exist if evolutionary theory is true
Archaeopteryx
An intermediate fossil that shows both reptile and bird characteristics.
Tiktaalik
"missing link" thought to be a transitional form between fish and amphibians
Problem with "missing link"
every time a "missing link" is found it created two more new missing links
Thomas Hunt Morgan
Bred fruit flies, and supported the the theory of chromosomal inheritance by finding that a specific gene is carried on a specific chromosome
Theodosius Dobzhansky
"Nothing in biology makes sense except in the light of evolution"
Sewall Wright, Ronald Fisher, J.B.S. Haldane
funders of populations genetics, mathematical models of evolution, statistical genetics
true-breeding plant
a plant that will always produce offspring with the same form of a trait when it self-pollinates
Non-true breeding plants
plants that produce some offspring that look different than the parent plants
The basic cross
between two trouble breeding plants resulting in hybrid offspring
P generation
Parental generation, the first two individuals that mate in a genetic cross
Cross fertilize
fertilization of one plant by pollen from a different plant
F1 generation
the first generation of offspring obtained from an experimental cross of two organisms, (offspring of the P generation)
Self Cross
crossing organism to itself (mostly just plants)
F2 generation
Offspring resulting from interbreeding of the hybrid F1 generation.
Mendel's five element model
1.) Parents transmit information about traits to their offspring
2.) Each individual receives one copy of each gene from each parent. (2 copies total)
3.) Not all copies of genes are identical
4.) The two alleles remain discrete, they do not blend
5.) The presence of a particular allele does not ensure that the trait it encodes will be expressed
Mendel's 1st Law of Segregation
two alleles segregate during gamete formation to be rejoined at random during fertilization
Mendel's 2nd Law of Heredity
In a dihybrid cross the alleles of each gene assort independently
Exceptions: factors assort independently
gene linkage
Exceptions: each trait is controlled by a single factor
polygenic inheritance
Exceptions: factors do not interact
Epistasis
Exceptions: each factor only controls one trait
Pleiotropy
Exceptions: factors only have two alternative outcomes
Incomplete dominance and codominance
Exceptions: factors are unaffected by the environment they are expressed in
environmental effects on expression
Polygenic inheritance
combined effect of two or more genes on a single character
Polygenic inheritance examples
height
Epistasis
A type of gene interaction in which a trait can be affected by more than one gene
Epistasis example
coat color in dogs
Pleiotropy
The ability of a single gene to have multiple effects
Pleiotropy example
sickle cell anemia
Incomplete dominance
parental phenotypes blend in the heterozygote
Codominance
heterozygotes show both parental phenotypes unblended
Environmental affects
can affect gene expression and influence genetically determined traits
Chromosomes
discovered in 1879, come in pairs, chromosomal theory of inheritance
Karyotype
A picture of all the chromosomes in a cell arranged in pairs
Chromatid
one half of a duplicated chromosome
Sister chromatids
Replicated forms of a chromosome joined together by the centromere
Centromere
Area where the chromatids of a chromosome are attached
Homologous pair
a pair of chromosomes, one from each parent
Ploidy
the number of copies of chromosomes
Haploid
a cell with one copy of a chromosome
Diploid
a cell with two copies of a chromosome
Polyploid
a cell with multiple copies of a chromosome (more than 2)
Crossing over
Process in which homologous chromosomes exchange portions of their chromatids during meiosis, highly variable
Gene linkage
Traits that tend to be inherited together as a consequence location on the chromosome (genes close together get linked together)