Bio0150 Final Review 12 14 11 11 39 AM Unit 2 Chapter 24 Understanding Evolution 1 Lamarck s theory acquired characteristics scala naturae species are not static but change through time claimed that simple organisms originate at the base of the chain by spontaneous generation and then evolve by moving up the chain over time Lamarckian evolution is progressive in the sense of always producing larger and more complex species created the great chain of being scale of nature scala naturae 2 The definition of evolution the unfolding descent with modification species that lived in the past are the ancestors of the species existing today and that species and their descendant species change through time descendant species are modified o o species change through time species are related by common ancestry change in allele frequencies in a population over time 3 Terms phenotype genotype fitness gene pool heritability allelic frequency phenotype the set of observable characteristics of an individual resulting from the interaction of its genotype with the environment genotype the genetic constitution of an individual organism fitness describes the ability to both survive and reproduce and is equal to the average contribution of the gene pool of the next generation that is made by an average individual of the specified genotype or phenotype gene pool the stock of different genes in an interbreeding population heritability proportion of observable differences between individuals that is due to genetic differences allelic frequency measurement that determines how frequent the allele expression of a particular gene arises in a population the result should be in close correlation with the laws of natural selection where more favorable alleles should become dominant in a species over time 4 Understand natural selection and its role in evolutionary processes the process where organisms better adapted to their environment tend to survive and produce more offspring o o as their size and shape genetically the individual organisms that make up a population vary in the traits they possess such some of the trait differences are heritable meaning that they are passed on to offspring o o in each generation many more offspring are produced than can possibly survive thus only some individuals in the population survive long enough to produce offspring and among the individuals that produce offspring some will produce more than others the subset of individuals that survive best and produce the most offspring is not a random sample of the population individuals with certain heritable traits are more likely to survive and reproduce natural selection occurs when individuals with certain characteristics produce more offspring than do individuals without those characteristics 5 Adaptation seed shape vs beak size example beak size correlates to the type of seed the bird can eat when a certain type of seed isn t produced then the bird that eats that seed will starve 6 Evidence for evolution and common ancestry under evolution by natural selection species are related by common ancestry and all have evolved through time 7 Beta defensin evolution example 8 Internal consistency genes 9 Applications of evolution and evolutionary medicine Chapter 12 Meiosis 1 Have a complete understanding of table 12 2 chromosome structure made up of DNA and proteins carries the cell s hereditary information o eukaryotes have linear threadlike chromosomes most bacteria and archaea have just one circular chromosome sex chromosome chromosome associated with an individual s sex o X and Y chromosomes of humans males are XY females XX Z and W chromosomes of bird and butterflies males are ZZ females are ZW Autosome a non sex chromosome o Chromosomes 1 22 in humans Unreplicated chromosome a chromosome that consists of a single copy Replicated chromosome a chromosome that has been copied consists of two linear structures Sister chromatids the chromosome copies in a replicated chromosome Homologous chromosomes in a diploid organism chromosomes that are similar in size shape joined at the centromere and gene content o 22 chromosomes from mother 22 from dad non sister chromatids chromatids belonging to homologous chromosomes tetrad homologous replicated chromosomes that are joined together haploid number the number of different types of chromosomes in a cell symbolized n o humans have 23 different types of chromosomes n 23 diploid number the number of chromosomes present in a diploid cell symbolized 2n o in humans all cells except gametes are diploid and contain 46 chromosomes 2n 46 ploidy the number of each type of chromosome present o equivalent to the number of haploid chromosomes sets present haploid having one of each type of chromosome n o bacteria and archaea are haploid as are many algae plant an animal gametes are haploid diploid having two of each type of chromosome 2n o most familiar plants and animals are diploid polyploid having more than two of each type of chromosome cells may be triplod 3n tetraploid 4n hexaploid 6n etc o seedless bananas are triploid many ferns are tetraplod bread wheat is hexaploid 2 Significance of homologous chromosomes ad their relation to haploid vs diploid number 3 Sex benefits and risks production of offspring through the fusion of gametes results in offspring that have chromosome complements unlike their siblings and their parents takes 2 individuals male female to produce 4 offspring thus two out of every four children that each female produces sexually the males can t have children of their own sexual individuals are likely to have offspring that lack deleterious alleles present in the parent 4 Meiosis allows for orderly mixing of genes be able to explain this paternal and maternal chromatids break and region at each chiasma producing chromatids that have both paternal and maternal segments crossing over when pairs of homologous chromosomes line up during meiosis I and the homologs separate a variety of combinations of maternal and paternal chromosomes can result each daughter cell gets a random assortment of maternal and paternal chromosomes 5 overall goal of meiosis I production of 2 haploid cells 6 overall goal of meiosis II production of 4 haploid cells each with one chromosome 7 process of meiosis meiosis I chromatids o interphase chromosomes replicate in parent cell in uncondensed state forming sister o early prophase I chromosomes condense nuclear envelope breaks up spindle apparatus forms synapsis