Bio Exam 1

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sedimentary rocks

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rocks formed by the accumulation of sediments

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strata

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layers of rock

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3 principles of stratigraphy

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1.Fossils of similar organisms are found in widely separated places on Earth.

2.Certain fossils are always found in younger strata, and certain other fossils are always found in older strata.

3.Organisms found in younger strata are more similar to modern organisms than are those found in older strata.

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relative ages of rocks

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oldest rocks lie at the bottom (Nicholaus Steno)

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half-life

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half of the atoms in a radioisotope decay to a stable isotope

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radiometric dating

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using half-lives to date fossils and rocks

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half-life and useful dating range carbon-14

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5700 and 100-60,000 years

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half-life and useful dating range uranium-234

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80,000 and 10,000-500,000 years

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half-life and useful dating range uranium-235

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704 million and 200,000-4.5 billion years

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half-life and useful dating range potassium-40

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1.3 billion and 10 million-4.5 billion years

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to use radio metric dating we must know

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the concentration of that isotope at the time of that event

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why are the radioisotopes in sedimentary rock to reliable to determine the date of its formation

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because these rocks are formed from materials that existed for varying lengths of time before being weathered, fragmented and transported to the sight of their deposition

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igneous rocks

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formed when molten lava cools

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radiometric dating of rocks older than 60000 yrs requires

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estimating radioisotope concentrations in igneous rocks

a preliminary estimate of the rocks age to determine which isotope to use

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paleomagnetic dating

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relates the ages of rocks to patterns in earths magnetism which change move and reverse over time which is recorded in sedimentary and igneous rocks

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other dating methods use

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info about continental drift, sea level changes, and molecular clocks

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how many eons are there and what are there names

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4: Hadean, Archean, Proterozoic, Phanerozoic

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Hadean eon

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the time on earth before life evolved

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Archean eon

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early history of life, ended when photosynthetic organisms appeared

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Proterozoic eon

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prokaryotic life diversified rapidly and the first eukaryotes appeared

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Phanerozoic eon

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eukaryotes rapidly diversified

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Precambrian

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the Hadean, Archean and Proterozoic eons and it accounts for the vast majority of geologic time

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plate tectonics

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the geophysics of the ,pavement of major land masses. the mechanism of continental drift

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earths crust

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thick continental and thinner oceanic plates over the malleable mantle

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where oceanic and continental plates converge

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thinner oceanic plate is forced under the continental plate.

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subduction

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when one plate is forced beneath another. results in volcanism and mountain

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when two oceanic plates collide

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one is subducted creating an oceanic trench

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when two continental plates collide

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the plates push up against each other creating mountains

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when continental plates diverge

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new crust forms resulting in rift valleys where lakes usually form

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mass extinctions

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when a large proportion of the species living on each disappear, can result from dramatic changes in earths physical parameters

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weather

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daily events at a given location

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climate

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long term average expectations over various seasons at a given location, changes slowly

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volcanic eruptions

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most produced only short lived effects but some can have major consequences

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meteorites

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smaller meteorites have little effect but larger ones have caused mass extinctions

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biota

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the assemblage of all organisms of all kinds living at a certain time or place

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flora

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all plants living at a certain time or place

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fauna

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all the animals livening in a certain time or place

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`why aren't there more fossils

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it is very unlikely that animals will become fossils and a lot of rocks get destroyed while some are inaccessible that contain fossils`

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precambrian life

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mostly small marine organisms but the number of species increased dramatically near the end`

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Paleozoic

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the first era of the Phanerozoic eon

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Cambrian period

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the first period of the Paleozoic era

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Cambrian explosion

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a geologically rapid diversification of life that took place in the early Cambrian

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Cambrian life

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multicellular life was largely or completely aquatic

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Paleozoic periods

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Cambrian, Ordovician, Silurian, Devonian, Carboniferous, Permian

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Paleozoic

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continents were in the southern hemisphere and lacked multicellular life. evolutionary radiation of marine animals was spectacular. at the 75% of animals became extinct because of environmental changes

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Silurian period

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continents merged, marine life rebounded, animals able to swim the open water appeared, first vascular plants evolved on land, first

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Devonian period

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terrestrial arthropods evolved as well terrestrial communities changed dramatically, first plants to produce seeds first forest soils, rates of evolutionary change accelerated, mass extinction of 75% of marine animals at the end maybe because of meteorite collision

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Carboniferous period

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extensive swamp forests in tropical ares, terrestrial diversity increased greatly, insects evolved wings

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Permian period

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Pangea formed, conditions for life deteriorated near the end resulting in the greatest mass extinction ever: 96% of all multicellular organisms became extinct

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periods of the Mesozoic era

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Triassic, Jurassic, and Cretaceous

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Triassic period

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invertebrates diversified, first frogs and turtles, radiation of reptiles began, first mammals appear, ended with a mass extinction: 65% of species on earth extinct probably due to a meteorite

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Jurassic period

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Pangea fully divided into 2 continents, lizards appeared and flying reptiles evolved, dinosaurs

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Cretaceous period

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continents we know today, life proliferated, flowering plants began their radiation, many mammals appeared, ended with mass extinction killing most animals larger than 25 kg probably due to meteorite

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Cenozoic era periods

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tertiary and quaternary

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Order of the eras of the Phanerozoic eon

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paleozoic, mesozoic, cenozoic

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tertiary period

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Indian met Asia

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Quaternary period

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current period, started with drastic cooling which pushed animals to the equator, started warning, humans appeared

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attributes of all organisms

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have cell membranes and ribosomes

have a common set of metabolic pathways, such as glycolysis

replicate DNA semiconservatively

use DNA as the genetic material to encode proteins, and use a similar genetic code to produce those proteins by transcription and translation

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prokaryotes

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bacteria and archea

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three domains of life

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bacteria, archea, eukarya

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prokaryotic organisms

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unicellular, do not divide by mitosis, no membrane enclosed nucleus, lack membrane enclosed cytoplasmic organelles

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peptidoglycan

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polymer that produces a mesh like structure around the cell. unique to bacteria and key difference between bacteria and archea

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gram stain

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lab technique, used to classify bacteria into 2 distinct groups gram-positive and gram-negative, where bacterial cells are soaked in violet dye, treated with iodine washed with alcohol and counterstained with red dye

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gram-positive bacteria

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appear blue to purple after test because of its cell wall which has 5x as much peptidoglycan

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gram negative bacteria

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appear pink to red after test because it has 5x less peptidoglycan

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common shapes of bacteria

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spheres, rods, spiral forms and names are based of these forms

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coccus

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spherical bacteria may live singly or associate in 2 or 3 dimensional arrays

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bacillus

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a rod shaped bacterium may be single, form chains or gather

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spirillum

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spiral bacterium may be single, form chains or gather

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less common bacterial shapes

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long filaments and branched filaments

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shape of archea

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less is know because few have been seen

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why is rRNA useful for phylogenetic studies

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evolutionarily ancient

all organisms have it

critical so lateral gene transfer is unlikely

slowly evolves allowing comparison between distantly related organisms

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lateral gene transfer

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genes moving sideways from one prokaryote species to another

can result in discordant gene trees, therefore consensus trees or trees based on genes that are not likely to laterally transfer are needed

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consensus tree

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comparison of multiple genes to create an organismal phylogeny

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genes most likely to be laterally transferred

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genes that result in a new adaptation that confers higher fitness on a recipient species

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8 major material groups

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1) the low-GC Gram-positives, 2) high-GC Gram-positives, 3) hyperthermophilic bacteria, 4) hadobacteria, 5) cyanobacteria, 6) spirochetes, 7) chlamydias, and 8) proteobacteria

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the low-GC Gram-positives

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aka Firmicutes have low ratio of GC base pairs, includes bacteria that can produce endospores, staphylococci, mycoplasma plasmas

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endospores

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heat resisting structures that some bacteria can produce, they replace the parent bacteria and lie dormant until they reproduce once they have found favorable conditions

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mycoplasmas

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lack cell walls, among the smallest cellular organisms known

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high-GC Gram-positives

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aka actinobacteria have an elaborately branched system of filaments, we derive mot of our antibiotics from these, includes bacteria that causes TB

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Hyperthermophilic bacteria

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live at very high temperatures

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Hadobacteria

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thermophilic extremophiles, can survive cold extremes as well as hot

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Cyanobacteria

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the first photosynthesizers, require few things to survive, contain photosynthetic lamellae (highly organized internal membrane systems), some colonies differentiate into vegetative cells, spores, or heterocysts

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vegetative cells (cyanobacteria)

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photosynthesize

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spores (cyanobacteria)

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resting stages that can survive harsh environments

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heterocysts (cyanobacteria)

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specialized for nitrogen fuxation

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spirochetes

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have spiral bodies and axial filaments allowing them to move in a corkscrew fashion, many are human parasites some are pathogens

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Chlamydias

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very small, live only as parasites, have a complex life cycle involving two forms of cells

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proteobacteria

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a large and diverse group, mitochondria originated with these, includes photoautotrophs, nitrogen fixers, e. coli, cholera

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2 characteristics shared by all archea

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the absence of peptidoglycan in their cell walls and the presence of lipids of distinctive composition in their cell membranes

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2 principal groups of archea

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crenarchaeota and euryarchaeota

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crenarchaeotes are found

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live in hot or acidic places

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euryarchaeotes

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some are methanogens (produce methane), some are extreme halophiles (salt lovers), some members have no cell wall

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biofilms

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a form microbal communities may take. upon contacting a solid surface, the cells bind to that surface and secrete a sticky, gel-like polysaccharide matrix that traps other cells. once a biofilm forms, the cells become more difficult to kill.

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fossil stromatolites

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large, rocky structures made up of alternating layers of fossilized biofilm and calcium carbonate—are among the oldest remnants of life on Earth

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quorum sensing

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on type of communication between prokaryotes

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microbiomes

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the communities of bacteria and archea that inhabit our bodies. very important for human health

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Koch's postulates

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The microorganism is always found in individuals with the disease.

The microorganism can be taken from the host and grown in pure culture.

A sample of the culture produces the same disease when injected into a new, healthy host.

The newly infected host yields a new, pure culture of microorganisms identical to those obtained in the second step.

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For an organism to be a successful pathogen, it must:

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arrive at the body surface of a potential host;enter the host’s body;evade the host’s defenses;reproduce inside the host; andinfect a new host.

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invasiveness

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the ability of a pathogenic bacteria to multiply in the hosts body

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toxigenicity

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the ability of a pathogenic bacteria to produce toxins

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endotoxins

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released when certain Gram-negative bacteria grow or lyse (burst), rarely fatal

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exotoxins

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soluble proteins released by living, multiplying bacteria, highly toxic, sometimes fatal

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obligate anaerobes

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prokaryotes that live by anaerobic metabolism because oxygen is toxic to them

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facultative anaerobes

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can shift their metabolism between anaerobic and aerobic

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aerotolerant anaerobe

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cannot preform aerobic respiration but oxygen does not damage them

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obligate aerobes

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unable to survive in the absence of oxygen and require oxygen for cellular respiration

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4 broad nutritional categories

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photoautotrophs, photoheterotrophs, chemoautotrophs, and chemoheterotrophs

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photoautotrophs

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preform photosynthesis, light is their energy source, carbon dioxide is their carbon source

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photoheterotrophs

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light is their energy source but must obtain carbon from organic compounds,

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chemoautotrophs

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obtain their energy by oxidizing inorganic substances and use some of that energy to fix carbon

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chemoheterotrophs

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obtain both carbon and energy from complex organic compounds