isci ch 17

what are the theories for the origin of life on earth

-spontaneous generation

-biogenesis

what is spontaneous generation

sudden emergence of living organ from nonliving material

what is biogenesis

living organisms come from other living organisms

what did Lois Pasteur discover

proved biogenesis to be true- 1862

what do we know from fossils

life has existed for 3.5 bya and earth was 4.6 bya (dormant)

what was the early earth atmosphere like

anoxic- no oxygen

who were Stanley miller and Harold Urey

they built a model of early earth in a chem lab (1953)

-water vapor, ammonia, methane, H2 simulated atm

-produced carbs, lipids, N bases

where else can production of these molecules occur

meteroites-brought by them

hydrothermal vents- deeps molecules

how did these become living cells

when lipids are added to water they create liposomes

-they grow, shrink, and divide

-reactions inside of membrane

-movement of molecues

-first nucleic acid!! RNA

what were the earliest living organisms on earth

marine prokaryotes

-no oxygen

what are heterotrophs

organisms that obtain energy and organic molecules from outside sources

what are autotrophs

organisms that are able to convert inorganic molecules into food and organic molecules

-photoautotroph

-chemoautotroph

when was the oxygen revolution

2.73 bya

who created the oxygen revolution

cyanobacteria

-released oxygen as a byproduct of photosynthesis

how did the oxygen revolution happen

1.most oxygen dissolves in water

2.react with iron atoms and precipitated out to form banded iron formations

3.continued dissolving water until water became satuated

4.after saturation, oxygen began to “gas out” and enter atmosphere

when did the first eukaryotes appear

2 bya

what do scientists believe happened for euk to evolve

mitochondria and chloroplasts evolved from prokaryotic that started to live inside the earliest euk cells

-energy conversion

what is the endosymbiotic theory

presence of euk explained

what was Charles Darwins boat name

HMS beagle

what did people think pre Darwin

earth and life do not change

what did the discovery of fossils show

species dissapear

new species appear

species change

-fossil organisms sometimes showed resemblance to modern species

what did Darwin observe on his journey

resemblance of island finches and mainland finch

resemblance of extinct species and living species

-difference in environment- adaptations

what is Darwins idea of descent with modification

1.species change over time

2.some split into new species

3.other species can go extinct

what was Lamarcks significance to Darwins theories

-same experiments, produced book before, but conclusions was the giraffes necks stretched

-darwin said adaptation and evolution- correct

do individuals evolve

GOD NO. NOO

do populations evolve

yessssss!!!!!!

what is adaptation

natural selection leads to the evolution of adaptations

-helps orgs to be well suited to live and reproduce in enviro

-usually associated with survival

what is antibiotic resistance

most classic example of natural selection

what was the first antibiotic discovered

penicillin

what is modern evolution

change in allele frequencies of genes over time

evolution characteristics

1.multiple alleles for a gene exist within a population

2.specific alleles may give orgs an advantage that allows it to reproduce more than others orgs in the pop

3.alleles that are advantageous pass on

what are the four evolutionary mechanisms

1.mutation

2.genetic drift

3.migration

4.natural selection

what is mutation

alteration of base pairs to change genes/ DNA

-ex. cat ears, curved or reg

what is genetic drift

random change in allele frequencies

-reduced gen variation in a pop

-ex potato famine and covid

WHAT IS THE IMPORTANT FACTOR THAT DISTINGUISHES GEN DRIFT FROM NAT SELEC

THE CHANGE IN ALLELE FREQUENCIES IS NOT RELATED TO THE ALLELE INFLUENCE OF REPROD SUCCESS

what are the two special cases of gen drift

-founder

-bottleneck

what is migration

gene flow: movement of a species from one pop to another

-changes allele frequencies

how does natural selection work

-must be variations in a population

-heritable traits

-traits lead to survival

-surviving orgs adapt and pass on to next gen

how do species form

speciation

-reprod barrier: prezygotic v postzygotic

what us a species

groups of orgs that can reproduce with each other and produce viable offspring

how do repros barriers form

allopatric and sympatric speciation

what is allopatric speciation

new species form due to a geographical barrier dividing one population into 2

-adaptive radiation- common ancestor diverges to diff species because live in diff environments

what is sympatric speciation

occurs without gen isolation

-planty

-polyploidy-  diploid mutates to have 3 or 4 chromosomes 

-hybridization

evidence of evolution

1.natural selection

2.artificial selection

3.similarities in body structure

4.vestigial structures

5.DNA and molecular evidence

6.patterns of development

7.biogeography

what are humans evolutionarily

primates, hominids

what are primates

group of mammals that includes monkeys and apes

what are the earliest hominids

australopithecus

-africa

-Lucy!

homo habalis

first homo!

2.2 mya

stone tools!

homo erectus

2 mya- 400k

left Africa!

homo sapiens and neanderthalensis

200k to 30k ya

homo Sapien sapiens

195k ya

ethiopia!