chapter1.pdf 70916 - BIOL 103 - 001
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This 9 page Class Notes was uploaded by Aimee Castillon on Tuesday September 1, 2015. The Class Notes belongs to 70916 - BIOL 103 - 001 at George Mason University taught by Gwendolyne Y Fondufe (P) in Fall 2015. Since its upload, it has received 421 views. For similar materials see Introductory Biology I in Biology at George Mason University.
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Date Created: 09/01/15
George Mason University Aimee Castillon acastil7gmuedu BIOL 103 Fall 2014 fulfil a Themes in the Study of Biology Name the properties of life The Properties of Life 0 biology scientific study of life 0 living things share the same properties 0 order complex organization of living things 0 regulation of internal conditions ability to maintain an internal environment consistent w life e respiration 0 growth and development consistent growth and development controlled by DNA 0 energy processing acquired energy and transforming it to form useful for the organism 0 response to environment ability to respond to environmental stimuli e temp regulation reproduction living things reproduce their own kind evolutionary adaptation acquisition of traits that best suit the organism to its environment De ne emergent properties Life 5 hierarchy of organization 0 Life emerges through organizations of various levels 0 emergent properties w each step upward in the hierarchy new properties List the hieraI39Chy 0f emerge that aren t present at the level just below it organizations 0 hierarchy of organizations 0 the biosphere consists of all the environments on Earth that support life 0 ecosystem consists of all the organisms living in a particular area and the nonliving environmental components e Florida Everglades community all living organisms in a particular ecosystem population consist of a localized group of individuals of a species organism individual living entity organ system composed of organs working together to perform specific functions e nervous system circulatory system etc organ provides specific functions for organism e brain spinal cord tissues made of groups of similar cells e nerve tissue connective ssue cells basic unit of life separated from its environment by a membrane organelles membranebound structure with a specific function Le 0000 O What is a cell what can cells do What are the two types of cells What are the differences between them mitochondria 0 molecules clusters of atoms Cells basic unit of life cells are the level at which properties of life emerge cell can 0 regulate internal environment 0 take in and use energy 0 respond to its environment 0 develop and maintain complex organzation 0 give rise to new cells two types of cells 0 eukaryotic contain membraneenclosed organelles including DNAcontaining nucleus I e plants animals and fungi o prokaryotic simpler and smaller than eukaryotic cells I lack nucleus and other organelles I e Bacteria and archaebacteria all cells 0 are enclosed by a membrane that regulates the passage of materials bt cell and its surroundings 0 use DNA as genetic info systems biology models the complex interactions of biological systems ranging from functioning of biosphere to complex molecular machinery of a cell cells illustrate another theme in bio the correlation of structure and function 0 structure is related to function at all levels of biological organization Interactions between living and nonliving components organisms interact w others and their env exchanging matter and energy 0 producers photosynthetic organisms that provide food in ecosystem o consumers organisms that eat plants or other animals 0 decomposers organisms that decompose wastes and remains of dead organisms chemical nutrients required for life make up the non living component ecosystem must accomplish two things 0 recycle chemicals necessary for life I most basic chemical nutrients flow from the air and soil to plants to animals and decomposers and back to air and soil 0 move energy through ecosystem I energy flows in a oneway direction through an ecosystem from the sun to producers to consumers and eventually converted to heat 0 energy therefore enters an ecosystem as light and exits as heat The unity of life based on DNA and a common genetic code all cells have DNA chem substance of genes Genes unit of inheritance that transmits info from parents to offspring o grouped into very long DNA molecules called chromosomes 0 control activities of a cell 0 each species genetic instructions are coded in sequences in 4 building blocks making up the DNA s helix shape 0 all forms of life use essentially same code to translate info stored in DNA into protein 0 differences in DNA sequence from individual to individual account for the genetic diversity in life 0 Genome Entire library of genetic info that organisms inherit o differential gene exposure 0 we can think of bids enormous scope as having two dimensions 0 vertical dimension size scale that stretches from molecules to biosphere 0 horizontal spans across the great diversity of organisms existing now and over the long history of life on Earth o diversity is hallmark of life 0 18 million species identified and named o taxonomy names species and classifies them into system of broader and broader groups Diversity of life 5 0 5 kingdoms Monera Protista Fungi Plantae and Animalia o 3 highlevel domains 0 Bacteria most diverse and widespread prokaryotes o Archaea like bacteria prokaryotic and live in extreme conditions 0 Eukarya everything else eukaryotic includes I protists protozoans and algae fungi animals plants Evolution process of change that has transformed life on Earth from its earliest beginnings to the diversity of organisms living today 0 fossil record documents that life has been evolving on Earth for many years amp pattern of ancestry 0 Charles Danvin Father of evolution 0 On the Origin of Species by Means of Natural Selection evidence to support evolution I descent w modification gt natural selection two observations 0 individual variation individuals in a population vary in their traits many of which are passed on to offspring o overproduction of offspring population can produce far more offspring than the environment can support 0 unequal reproductive success 0 accumulation of favorable traits over time 0 Natural selection is an editing mechanism 0 exposure of heritable variations to env factors that favor some individuals over others 0 DanVin realized that numerous small changers in populations as a result of natural selection could eventually lead to major alterations of species Process of Science Scientific Inquiry 0 science To know 0 based upon inquiry search for info and explanations of natural phenomena o scientists typically I make observations I form hypothesis proposed explanations for a set of observations I test them 0 Two types of data 0 qualitative data is descriptive o quantitative data includes num measurements 0 scientist use 0 inductive reasoning to draw general conclusions from observations I example All organisms are composed of cells 0 deductive reasoning to come up with ways to test hypothesis I involves drawing specific conclusions from some general principle I le if all organisms are made of cells and humans are organisms then humans are composed of cells we solve everyday problems by using hypothesis science is repetitive o if hypothesis supported the experiment is repeated and results verified by other researchers 0 if results don t support hypothesis it s revised and tested further 0 theory vs hypothesis 0 theory is much broader in scope generally enough to generate many new specific hypotheses and supported by a large and usually growing body of evidence 0 science is a social activity in which scientists 0 work in teams 0 share info through peerreviewed publications meetings and personal communication 0 build on and confirm each other s work 0 science seeks natural causes for natural phenomena 0 scope of science is limited to the study of structures and processes that we can directly observe and measure 0 hypotheses about supernatural forces or explanations are outside the bounds of science because they generate hypotheses that cannot be tested by science Scientific Thinking Hypotheses can be tested using controlled field studies 0 observation many animals match their environment 0 hypothesis color patterns have evolved as adaptations that protect animals from predators c this was tested controlled experiment are conducted to test hypothesis that color patterns have evolved as adaptations that protect animals from predation 0 experimental group consisted of noncamouflaged mice models and control group consisted of camouflaged mice that matched their native to each area groups differed by one factor the coloration of mouse model results 0 noncamouflaged mice had a higher percentage of attacks in beach and inland areas thus data supports hypothesis Biology and Everyday Life Evolution is connected to our everyday life evolution is core theme of biology connected to everyday life humans can selectively breed plants and animals organisms are also being genetically engineered o humans are agents of evolution humans unintentionally cause 0 evolution of antibioticresistant bacteria 0 of pesticideresistant pests 0 loss of species through habitat loss and global climate change Connection Biology technology and society are connected in important ways many issues facing society are related to biology and often involve expanding tech basic goals of science and tech differ although goals differ science and tech are interdependent 0 research benefits from new tech 0 tech advantages tech of DNA manipulation are the results of scientific discovery of structure of DNA George Mason University Aimee Castillon student email address BIOL 103 0 Fal2014 U gm 7 g fvgicl 17le F If f7 glang l l Hg 72 i 39 K r L m A VV 39L 5 f 02 71127312 Viva 1 I v 1 xll liMliiiiyf llligllguglquot l x gll l l llg t igill Defining Species o Microevolution change in the gene pool of a population from one gen to the next 0 speciation process by which one species splits into 2 or more species 0 every time this occurs the diversity of life increases 0 the many millions of species on Earth have all arisen from ancestral life form that lived around 35 billion years ago 0 over the course of 35 billion years 0 an ancestral species first gave rise to two or more diff species 0 then branched to new lineages 0 then branched again 0 until we arrived at the millions of species that live or lived on Earth There are several ways to define a species 0 species is Latin for kind or appearance devising formal def of species isn39t easy and raises s such as 0 how similar are members of same species 0 whereas indv ls of many species exhibit fairly limited variation in physical appearance certain other species seem extremely varied o biological species concept group of populations whose members have the potential to interbreed in nature and produce fertile offspring 0 Therefore members of a species are similar bc they reproduce w each other 0 reproductive isolation prevents members of diff species from mating w each other prevents gene flow bt species and maintain separate species 0 therefore species are distinct from each other bc they don t share the same gene pool 0 biological species concept can be problematic 0 some pairs of clearly distinct species occasionally interbreed and produce hybrids le grizzly bears polar bears grolar bears o reproductive isolation cannot usually be determined for extinct organisms known only from fossils o doesn t apply to prokaryotes or other organisms that reproduce only asexually 0 Therefore alternate species concepts can be useful 0 Morphological species concept classifies organisms based on observable physical traits and can be applied to asexual organisms and fossHs 0 however there s subjectivity in deciding which traits to use 0 Ecological species concept defines species by its ecological niche and focuses on unique adaptations to particular roles in a biological community 0 For example two species may be similar in appearance but distinguishable based on what they eat or where they live 0 Phylogenetic species concept defines a species as the smallest group of individuals that shares a common ancestor and thus forms one branch of the tree of life 0 biologists trace phylogenetic history of species by comparing its morphology DNA sequence or biochem pathways 0 however defining amount of diff required to distinguish separate species is a problem 0 Reproductive barriers serve to isolate the gene pools of species and prevent interbreeding 0 depending on whether they function before or after zygotes form barriers are categorized as o prezygotic I 5 types 0 habitat isolation two species live in same area but not the same species 0 temporal isolation two species breed at different times 0 behavioral isolation there s little or no mate recog bt females and males of diff species 0 mechanical isolation female and male sex organs aren t compatible 0 gametic isolation female and male gametes aren t compatible 0 postzygotic I 3 types 0 reduced hybrid viability most hybrid offspring don t develop fully or don t survive 0 reduced hybrid fertility hybrid offspring are vigorous but can t reproduce viable offspring 0 hybrid breakdown firstgen hybrids are viable and fertile but the offspring of the hybrids are feeble or sterile Mechanism of Speciation Allopatric speciation o Allopatric speciation populations of the same species are geographically separated isolating their gene pools 0 gene flow bt the population is prevented o Populations separated by a geographic barrier are called allopatric populations Sympatric speciation takes place wlo geographic isolation o sympatric speciation new species arises win same geographic area as a parent species 0 how can reproductive isolation develop when members of sympatric populations remain in contact w each other 0 gene flow bt populations may b reduced by I polyploidy cells have more than two complete sets of chromosomes 0 diploid having 2 complete sets of chromosomes I habitat differentiation or I sexual selection 0 failure of cell division after chromosome duplication could double a cell s chromosome number from diploid 2n to tetraploid 4n 0 if selffertilization occurs the resulting tetraploid zygotes would develop into plants that can reproduce fertile tetraploid offspring by selffertilization or by meeting w other tetraploids o a tetraploid can t produce fertile offspring by mating w a parent diploid plant 0 formation of a tetraploid therefore is an instantaneous speciation event new species which is reproductively isolated 0 most polyploid species arise when 2 different species interbreed and produce hybrid offspring normally the hybrid is sterile bc its chromosomes can t pair although far more common in plants polyploid speciation occurs occasionally in animals 0 sympatric speciation in animals is more likely to happen through habitat differentiation or sexual selection than by poypoidy 0 Le cichlid fish 0 adaptation for exploiting diff food sources may have evolved in different subgroups of the original cichlid population 0 if these sources were in different habitats mating bt the populations would become rare 0 the gene pools would become isolated as each population became adapted to a different resource 0 Sexual selection in which females choose their mates based on appearance coloration in this case may have also been a factor in the speciation of these brightly colored fish 0 Such mate choice can contribute to reproductively isolating populations thus keeping the gene pools of newly forming species separate 0 Both habitat differentiation and sexual selection contribute to forming reproductive barriers between allopatric species Evolution Connection Most plant species trace their origin to polyploid speciation 0 plant biologists estimate that 80 of all living plant species are descendants of ancestors that formed by polyploid speciation hybridization bt two species accounts for most of these species 0 Le wheat cotton peanuts etc Isolated islands are often showcases of speciation 0 most of species on Earth are thought to have originated by allotrapic speciation o isolated island chains offer some of the best evidence of this type of speciation 0 multiple speciation events are more likely to occur in island chains that have 0 physically diverse habitats o islands far enough apart to permit populations to evolve in isolation and o islands close enough to each other to allow occasional dispersions bt them 0 evolution of many diverse species from a common ancestor is adaptative radiation 0 Le Galapagos Islands 14 closely related finches Danvin s finches Hybrid zones provide opportunities to study reproductive isolation 0 hybrid zones regions in which members of different species meet and mate to produce at least some hybrid offspring o 3 possible outcomes I reinforcement strenghtening of reprod barriers 0 when hybrid offspring are less fit than members of both parent species 0 natural selection to strenghten or reinforce reproductive barriers thus reducing the formation of unfit hybrids and o barriers bt species should b stronger where the species overlap I fusion weakening of reprod barriers 0 gene flow bt species increases and gene pool of the two species become increasingly alike 0 in effect speciation process reverses eventually causing two hybridizing species to fuse into single species 0 Le cichlid species in Lake Victoria I stability continued formation of hybrid individuals 0 in fact many hybrid zones are stable as hybrid offspring continue to be produced Speciation can occur rapidly or slowly o punctuated equilibria model draws on the fossil record which states 0 change most as they arise from an ancestral species and then 0 experience relatively little change for the rest of their existence 0 what is the total length of time bt speciation events bt formation of a species and subsequent divergence of that species 0 it varies considerably 0 Data suggests that on average millions of years may pass before a newly formed species will itself give rise to another new species
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