Unit 2 - Genetics and Evolution

ChromosomeA threadlike, gene-carrying structure found in the nucleus. Each chromosome consists of one very long DNA molecule and associated proteins.homologous chromosomesChromosomes that have the same sequence of genes and the same structureExplain the difference between an allele and a genea gene is a unit of hereditary information, an allele is a variation of a specific geneRNAribonucleic acidWhat is the difference between a chromosome and a chromatid?A chromosome consists of two chromatidsWhat is a true breeding organism?an organism that produces offspring that are genetically identical for one or more traits when self pollinated or crossed with another organism with same traitsAllele definitiondifferent versions of the same gene, found in the same spots in homologous chromosomesWhat is cloning with an exampleProducing an individual that is genetically identical to another using cells or tissue. ex. Dolly the sheepPhenotypeAn organism's physical appearance, or visible traits.Purpose of a ______ squareA punnet square is used to show different possible combinations of alleles, also to give information about genotypes and phenotypesWhat is non-disjunctionthe failure for chromosomes to separate completely during meiosis (not moving to poles of cell)____________ is an example of non-disjunctionAn extra chromosome 21 (trisomy/down syndrome)Name types of muscle dystrophy- Myotonic (autosomal, dominant) - Becker (x-linked, recessive) - Duchenne (x-linked, recessive) - Limb-girdle (autosomal, recessive)sex-linked disordersdieseases that are determined by genes found on the sex chromosomes. particularly the X chromosomex-linkedA gene carried on the X chromosome. If a male inherits an X-linked recessive trait from his mother, he expresses that trait because the Y from his father has no counteracting gene. Females are more likely to be carriers of X-linked traits but are less likely to express them.y-linkedThe pattern of inheritance that results from genes located only on the Y chromosome. Is much less common than x-linked and only seems in malesNucleotideThe repeating unit in DNA; it comprises a deoxyribose sugar, a phosphate group, and one of the four nitrogenous basesWhen looking at a pedigree chart, how can you prove the trait is recessive?- If it skips generations - if two unaffected parents have an affected childWhen looking at a pedigree chart, how can you prove it is not x-linked- If men and women are equally affected - if an unaffected father has an affected daughterWhat are the three main components of DNApentose sugar, phosphate group, nitrogenous baseautosomal inheritanceInheritance of a genetic trait not on a sex chromosomePedigreeA diagram of an individuals ancestors used in human genetics to analyze Mendelian inheritance of a certain traitcodominancea situation where both alleles are expressed fully to produce offspring with a third phenotype. splotchy phenotypic expression ie calico catsincomplete dominanceSituation in which one allele is not completely dominant over another allele. Smooth, homogeneous phenotypic expression ie mixed coloured animals, a black and a white rabbit produce grey offspringWhat base letters are complimentary?Thymine (T) and adenine (A) Guanine (G) and cytosine (C)point mutationa mutation affecting only one or very few nucleotides in a gene sequence. It could be beneficial, harmful, or neutraltest crossa crossed used to determine the genotype of an animal expressing a dominant traitHow does a test cross work?- If all the offspring display the dominant phenotype, then the individual is homozygous dominant - If the offspring displays both dominant and recessive phenotypes, the individual is heterozygousWhat is an example of a cross with multiple alleles and dominance hierarchies- Fruit fly eye color - Human eye colorGenotypegenetic makeup of an organismspontaneous mutationa mutation that is not caused by any outside factors; it occurs randomlyInduced mutationa mutation that occurs because of exposure to an outside factor, ex. smokingLaw of independent assortmentIf genes are located on separate chromosomes, they will be inherited independently of one anotherdihybrid crossa cross that involves two genes, each consisting of heterozygous allelesProduct lawthe probability of two independent random events both occurring is the product of the individual probabilities of the eventsWhat is mitosis used for?growth, repair, asexual reproductionWhat are the stages of mitosisinterphase (genetic material is duplicated), prophase (nuclear membrane starts to dissolve), metaphase (spindle fibers align chromosomes and move to center of the cell), anaphase (centromeres divide and chromatids move to opposite ends of cell), telophase (nuclear membranes begin to form around the chromosomes)Reproductive cloning can also be calledsomatic cell nuclear transferDescribe the process of somatic cell nuclear transferThe nucleus is removed from a donor egg cell, and replaced with a removed nucleus from the donor to be cloned. This is then planted in a surrogate mother, and birthedPurpose of meiosisproduce gametes for sexual reproductionProcess of meiosis1) INTERPHASE : Genetic information duplicates and the chromosomes form pairs 2) METAPHASE 1 : In the first division, the chromosome pairs line up in the centre of the cell 3) ANAPHASE 1 / TELOPHASE 1 : The pairs are pulled apart so each new cell only has one copy of each chromosome 4) PROPHASE 2 / METAPHASE 2 / ANAPHASE 2 : In the second division, the chromosomes line up again in the centre of the cell and the arms of the chromosomes are pulled apart 5) TELPPHASE 2 / CYTOKINESIS : Four gametes are formed, each with only a single set of chromosomes in it - each gamete is genetically different from the others.Spermatogenesisthe production of sperm cellsOogenesisthe production, growth, and maturation of an egg, or ovum. At the second meiotic division, the is one ovum that is bigger than the other three polar bodiesHow does meiosis help to create genetic diversity?- during interphase, the alleles cross over, which switch around the genotypes of the DNA - dominant and recessive genes mean that different traits can be carried through generations without being known (recessive genes)Who is your favorite Austrian monk?Gregor MendelExplain Mendels experimentsMendel proposed that certain traits were dominant over others. He noticed that with certain traits if you crossed true-breeding plants of different traits, then the offspring would have only one of the two traits. This was all before chromosomes were discovered. He did this by crossing Pea plants.BiotechnologiescRISPR gene therapyWhat are the nitrogenous bases?Adenine, Thymine, Guanine, CytosineMendel's law of inheritance1. If genes are located on separate chromosomes they are inherited independent of each other. 2. When genes cross over to homologous chromosomes and they are far apart on the chromosome, it will be an independent traitchromosome mutationan error that involves an entire chromosome or a large part of a chromosomeP generationParental generation, the first two individuals that mate in a genetic crossF1 generationthe first generation of offspring obtained from an experimental cross of two organisms (from the P generation)monohybrid crossA cross between individuals that involves one pair of contrasting traitsF2 generationoffspring of the F1 generationtrue-breeding organisman organism that produces offspring that are genetically identical for one or more traits when self-pollinated or when crossed with another true-breeding organism for the same traitshybridthe offspring of two different true-breeding plantsmutationa change in the genetic code of an allele; the change may have a positive, neutral or harmful effectartificial selectiondirected breeding in which individuals that exhibit a particular trait are chosen as parents of the next generation, this is used to produce new breeds or varieties of plants and animalsFossilAny ancient remains, impressions, or traces of an organism or traces of its activity that have been preserved in rocks or other mineral deposits in Earth's crustPalaeontologythe scientific investigation of prehistoric life through the study of fossilsHomologus featuresA structure with a common evolutionary origin that may serve different functions in modern species (ex bat wings and human arms)analogous featuresa structure that performs the same function as another but is not similar in origin or anatomical structure; for example, bird and insect wingsvestigial structuresa rudimentary and non-functioning, or only marginally functioning, structure that is homologous to a fully functioning structure in closely related speciesAdaptationA characteristic that improves an individual's ability to survive and reproduce in a particular environment.Natural selectionthe way in which nature favours the reproductive success of some individuals over othersRadioisotopesIsotopes that have unstable nuclei and undergo radioactive decay.Gene poolthe complete set of alleles contained within a species populationHominidall species descended from the most recent common ancestor of chimpanzees and humans that are on the human side of the lineageCambrian Explosionthe rapid evolution of most major animal phyla that took place over approximately 40 million years during the Cambrian periodAdaptive Radiationthe relatively rapid evolution of a single species into many new species, filling a variety of formerly empty ecological nichesCatastrophismthe theory that the pattern of fossils could be accounted for by a series of global catastrophes that wiped out most species on Earth (Baron Georges Cuvier)Uniformitarianismthe theory that geological changes are slow and gradual and that natural laws and processes have not changed over time (Sir Charles Lyell)Sexual selectiondifferential reproduction as a result of variation in the ability to obtain mates; results in dimorphism, and mating and courtship behavioursWhat makes an individual more favoured for mating?Traits that make them more likely to breed successfully and produce more offspringWhat is the female strategy for maximizing evolutionary fitness?Make the male jump through hoops(often with an energetic cost or risk) to ensure that he will provide here young with the best gene (quality over quantity)What is the male strategy for maximizing evolutionary fitness?Mate with as many partners as possible to maximize number of offspring produced (quantity over quality)stabilizing selection- occurs when environmental conditions are relatively stable - Individuals that are near the average for a particular trait are favored - ex. human children weigh slightly more than 3kg at birthDirectional Selection- Occurs after the migration of a population to a new environment or after an environmental change - Individuals with more extreme phenotypes are favored - ex. hummingbirds with longer bill lengths move to an island whose flowers are longer.reproductive isolating mechanismsmechanisms that prevent interbreeding between different speciesDisruptive selection- Occurs in response to multiple food sources that require different forms of a trait - Individuals with phenotypes at opposite extremes of the range are favored over those with average phenotypes - Small and large bills are favored over medium-sized bills in the black-bellied seed cracker finch in response to two different seed sizes being available4 requirements for evolution to occur- Individuals within a species vary in many ways - Some of this variability is heritable - every generation produces more offspring than can survive - Populations of species tend to remain stable in size; due to environmental constraintsExplain Darwin's theory of natural selectionProcess by which organisms that are most suited to their environment survive and reproduceGive some examples of artificial selection- Belgian blue cattle breed - "pure breed" dogsFounder Effectgenetic drift that results when a small number of individuals separate from their original population and establish a new population (founding their own population)Bottleneck effectthe result of a severe restriction in population sizeHow does repopulation occur after the bottleneck effect?A small sample of the population has to repopulate therefore making the allele frequencies different than the original population and resulting in a lack of genetic diversity.prezygotic reproductive isolating mechanismsprevents interspecies mating and fertilization; Behavioural:different mating behaviours (birds of paradise) Temporal: different matting seasons (deer and elk) Ecological: different habitats (largemouth bass and small mouth bass) Mechanical: Incompatible sex organs Gametic: incompatible sperm and egg (dogs and cats)postzygotic mechanismsPrevents fertilized egg (zygote) from becoming from growing into viable, fertile adult. Zygotic mortality: zygotę wont develop properly (sheep and goats) Hybrid inviability: embryo develops but dies at birth or before adulthood (tigers and leopards) Hybrid sterility: individual develops into adulthood and is healthy but sterile (donkey and horse (mules))SpeciationFormation of new speciesSympatric Speciationthe evolution of a population in one geographic area into separate speciesAllopatric SpeciationThe formation of a new species as a result of evolutionary changes following the a period of geographical isolationConvergent EvolutionThe evolution of similar traits in distantly related speciesDivergent Evolutionthe large-scale evolution of a group into many different formsCoevolutionProcess by which two species evolve in response to changes in each otherPrimateA group of relatively large-brained, mostly arboreal mammals that includes prosimians, monkeys, apes, and humansPolyploidmultiple sets of chromosomesHow do humans impact speciation?habitat destruction that isolates populations resulting in inbreeding; essentially works like allopatric speciationClosely related species share __________________homologous featuresEvidence that species can change- fossils of extinct species hav been found - fossils that show organisms becoming more diverse over time (Transitional forms) - unique animals on islands that are similar to those on nearby continents - homologous and vestigal featuresEvidence that Earth is not immutable- fossils of sea creatures were found at high levels showing mountains rose from oceansContributions of BuffonHe believed that species could change over timeContributions of CuvierIntroduced the theory of catastrophism. This means that species went extinct and landscapes changed after catastrophes. Also believed that god replaced those speciesContributions of LyleIntroduced the theory of Uniformitarianism. This means that slow geological processes, such as erosion shaped earth over large time periods. Also thought that the earth must be ancient.Contributions of LamarckHe believed that Species were changed due to their environment (THIS WAS WRONG), and passed on traits to offspring.contributions of Charles DarwinDarwin introduced the theory of natural selection, and introduced the theory of evolution. (humans evolved from apes)sexual dimorphismDifferences in physical characteristics between males and females of the same species.Why does sexual dimorphism occur?males and females invest differently in reproduction. In birds males need to be bright and colourful to attract females whereas female being a bright colour would be a disadvantages they would attract predators to the nest.homologous structures examplesfinger bones in whale flippersanalogous structure examplebird wing and insect wingvestigial features examples-goosebumps of humans -extra toes on dogs -pelvis bone in whalestransitional formsfossils that connect ancestral species with their descendants through a series of tiny stepssignificance of ArchaeopteryxConsidered to be the "first bird" known thus far. It is the closest transition between dinosaurs and birds.genetic driftA change in the allele frequency of a population as a result of chance events rather than natural selection.theory of punctuated equilibriumattributes to most evolutionary changes to relatively rapid spurts of change followed by long periods of little to no change -fossil records often show new species appearing quite suddenly then remaining the sameKey events in Earth's history3.8 bya cells first appears on earth 1.2 bya eucharyotic cell containing mitochondria 900 mya animals appear 542 mya Cambrian explosion 435 mya plant appear 251 mya 90% of marine life goes extinct 65 asteroid causes mas extinction (dinos)Theory of GradualismAttributes large evolutionary changes in species to the accumulation of many small and ongoing changes and processes. - fossils of transitional forms foundsignificance of Aetiocetustransitional form of whale that shows the movement of the nostrils from front to top of the head.significance of Taktaaliktransitional form of amphibians that connects amphibians to fish.Compare homologous and analogous structures.Homologous structures look similar and have the same origin but have different functions whereas analogous structures do not look similar, have different origins but perform the same function.