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Biology Sheet #1

factors preventing evolution: maintaining stability of the gene pool -all mating is random -isolation from other populations of the same species -large population size -no gene mutation -lack of selection pressure (when the gene has no effect on survival or reproduction)
factors causing evolution: disturbing stability of the gene pool -gene mutation (infrequent but inevitable) -gene flow (immigration/emigration) natural selection -genetic drift
gene mutations heritable changes in DNA that give rise to altered gene products
can mutations be predicted? no
how many gametes in a single reproductive season has a new mutation rate? 100,000 in 1,000,000
what can mutations cause? changes in structure, function, or behavior
types of mutations -lethal, if it has drastic effects -beneficial, when adds an advantage to the individual (eg. mutated corn growing faster)
mutation rates number of events that produce mutated alleles per locus per generation
locus position occupied by a gene on a chromosome
factors influencing mutation rate -size of gene (larger genes = bigger target for mutation) -nucleotide sequence (repeats more likely to be mutated) -spontaneous chemical changes (GC bases more prone) -environmental factors (radiation and chemicals) -radiation -chemicals
emigration individuals leave population
immigration new individuals enter a population
gene flow physical flow of genes
what does gene flow do? helps keep separate populations genetically similar (ex. human population)
gene drift random change in gene frequencies over generations
how is gene drift brought about? by change only
founder's effect when few individuals leave a population and establish a new one elsewhere
bottleneck effect it is a severe reduction in population size brought about by intense selection pressure or natural calamity (ex. loss of habitat, contagious disease, volcano, hunting)
natural selection -survival of the fittest -the outcome of difference in survival and reproduction among individuals that show variation in heritable traits
over generations, what does natural selection lead to? increased fitness or an increase in adaptation to the environment
types of natural selection -stabilizing -directional -disruptive -sexual -frequency dependent
evidence of ancient life comes from fossils containing layers of sedimentary rocks over vast areas
geographical distribution of species many similarities between animals from different continents show that animals must have evolved on the same land mass-part of early super continent - gondwana, earlier called pangea
theory of continental drift over the past 3.8 billion years, changes in land, ocean, and atmosphere profoundly influenced the evolution of life (geographical distribution changes)
embryology the early embryo of vertebrates strongly resemble one another because they have inherited the same ancient plan of development
homologous structures similarity in one or more body parts in different organisms (ex. vertebrate forelimb)
biochemistry biochemical similarities in DNA/RNA/proteins are greatest among the closely related species and weakest among the most distantly related
evidence for theory of evolution -evidence of ancient life -geographical distribution of species -embryology -homologous structures -biochemistry
fossils stone hard physical evidence of ancient life that are present in sedimentary rock with the deeper the layer resembling older fossils
fossilization a slow process that starts when an organism of its traces become buried in volcanic ash or in sediments at the bottom of lakes, lagoons, or seas
where are similar fossils found? similar fossils containing layers of sedimentary rock are found over vast areas, even on different continents
stratification the layering of sedimentary deposits
Darwin's theory of evolution -4 facts -2 deductions
4 facts of Darwin's theory of evolution -great prolificity in nature -no of individuals of a species remains constant over time -resources of earth are limited -individual variation is the raw material for evolution
2 deductions of Darwin's theory of evolution -struggle for existence, food, light, and, water -survival of the fittest occurs through the mechanism of natural selection
how much DNA is shared between monkeys and humans? 99% of genes are shared. chimpanzees are closer to us than gorillas
how many kingdoms did Linnaeus originally propose? 2 - plants and animals
whittaker's five kingdoms -monera -protista -fungi -plantae -animalia
woese's three kingdoms -eubacteria -archaebacteria -eukaryotes
monera single celled organisms (bacteria)
protista single celled or multi celled eukaryotes with greater internal complexity compared to bacteria
fungi -multi celled eukaryotes -feed by digestion -decomposers, pathogens, parasites
plantae -multicellular -eukaryotes
archaebacteria -single celled prokaryotes -thrive in unusually harsh places like hot water near volcanos -differ from typical bacteria in chemical composition (cell wall and membrane characteristics)
Created by: studystack_0325