2 Learning Target 1I can explain how offspring acquire genes from parents by inheriting chromosomes.I can distinguish between asexual and sexual reproduction.
3 Where do your genes come from? Ever wonder where you got your traits from?And where they got their traits from?
4 What’s a gene? A segment of DNA which codes for a protein Can code for an enzyme, a structural protein or a regulatory proteinThis determines an organism’s traitsMore next unit…
5 Asexual reproduction No gametes produced One parent Prokaryotes – binary fissionSingle-celled eukaryotesYeast – buddingAmoeba – binary fissionSimple multicellular eukaryotesHydra – buddingComplex multicellular eukaryotes - regenerationSea starsPlanaria
6 Sexual Reproduction Gametes produced by meiosis Two parents Direct contact not requiredPlants: pollination strategies varyAnimals: release of gametes into environment (aquatic)
7 I can distinguish between the following pairs of terms: Learning Target 2I can distinguish between the following pairs of terms:Somatic cell and gameteAutosome and sex chromosomeDiploid and haploidZygote and fertilization
8 Important Vocabulary Diploid Haploid Somatic cell Gamete Diploid Body cellGameteReproductive cell (sperm or egg)DiploidContains 2 sets of homologous chromosomes (2n)HaploidContains 1 set of homologous chromosomes (n)Diploid Haploid
9 Important Vocabulary, CONT. ZygoteFertilized eggFertilizationUnion of sperm and egg cells in sexual reproductionAutosomeChromosome 1-22 (everyone has)Sex chromosomeChromosome (XX = female, XY= male)
10 I can explain how haploid and diploid cells differ from each other. Learning Target 3I can explain how haploid and diploid cells differ from each other.I can state which cells in the human body are diploid and which are haploid.
11 Haploid Vs. Diploid Somatic cells are diploid Only gametes are haploid – why?
12 Learning Target 4I can explain how meiosis generates haploid daughter cells from diploid parent cells.I can list the phases of meiosis I and meiosis II and describe the events characteristic of each phase.I can describe what homologous chromosomes are.I can explain how the spindle fiber separates either homologous chromosomes of sister chromatids.I can recognize the phases of meiosis from diagrams or micrographs.I can explain how genetic recombination occurs.
13 Meiosis: Production of gametes Alternating processes, alternating stagesChromosome number must be reducedDiploid Haploid2n nHumans 46 23Meiosis reduces chromosome numberFertilization restores chromosome numberHaploid Diploidn 2nNecessary for sexually reproducing organisms to produce gametes
14 Steps of Meiosis Meiosis I DNA replication Meiosis II InterphaseProphase IMetaphase IAnaphase ITelophase IMeiosis IIProphase IIMetaphase IIAnaphase IITelophase IIDNA replication1st division of meiosis separates homologous pairs2nd division of meiosis separates sister chromatids*just like mitosis*
15 Homologous chromosomes Paired chromosomesBoth chromosomes carry a pair of genesControl same inherited charactersHomologous = same informationChromosome 17
20 Learning Target 6I can explain how independent assortment, crossing over and random fertilization contribute to genetic variation in sexually reproducing organisms.
21 Independent assortment Random orientation of homologues at metaphase plate during metaphase IIndependent assortment in humans produces 223 (8,388,608) different combinations
22 Crossing Over During Prophase I Homologous pairs swap pieces of chromosomeSister chromatids intertwine and cross over each otherBreakage and re-fusing of DNACreates completely new combinations of traits in the next generation
23 Random fertilization Random ovum fertilized by a random sperm Any 2 parents will produce a zygote with over 70 trillion (223 x 223) diploid combinations
24 Learning Target 7I can explain why heritable variation is crucial to Darwin’s theory of evolution by natural selection.
25 Sexual reproduction creates variability Allows us to maintain both genetic similarity and differencesWhy is this significant to evolution by natural selection?