Test 2 Study Guide Lecture 11 Sexual Reproduction Concepts Know that asexual reproduction results in genetically Identical offspring Know that asexual reproduction is genetically the same as cloning Know that sexual reproduction results in genetically similar but not identical Know that asexual reproduction is the result of mitosis Know that chromosomes exist as homologous pairs in diploids Know and understand why meiosis produces haploid daughter cells from offspring diploid parents Know that sexual life cycles alternate meiosis and fertilization Know that sexual life cycles vary in the timing of meiosis and fertilization Terms to Know Haploid diploid homologous chromosome homologous pair sister chromatid gamete zygote meiosis fertilization gonad sexual reproduction asexual reproduction clone spore gametophyte sporophyte 1 Haploid a cell with one set of chromosomes n chromosomes normally in gametes of sexually reproducing animals 2 Diploid a cell with two sets of chromosomes 2n chromosomes 3 Homologous chromosomes a pair of chromosomes of the same length centromere position and staining pattern that possess genes for the same characters at corresponding loci one homologous chromosome is inherited from the mother and one from the father homologs genetically similar but not identical 4 Sister chromatid joined copies of one chromosome they separate from each during anaphase of mitosis so that each daughter cell gets a copy of the chromosome identical to one another 5 Gamete a haploid reproductive cell usually an egg or sperm that combines with another gamete to produce a diploid zygote during sexual reproduction 6 Zygote the diploid cell produced by the union of haploid gametes during fertilization 7 Meiosis cellular division in which one diploid cell produces 4 genetically different haploid daughter cells process by which gametes are produced 8 Fertilization the union of two gametes during sexual reproduction results in 9 a diploid zygote Gonad the male and female sex organs that produce gametes testes in male and the ovaries in females 10 Sexual reproduction process by which gametes from 2 organisms join one another during fertilization to produce a diploid zygote increases genetic variability within population 11 Asexual reproduction process by which an organism reproduces through mitosis the result is a genetically identical daughter cell there is no genetic variability between the parent cell or daughter cell 12 Clone a lineage of genetically identical individuals reproduce through mitosis 13 Spore in the life cycle of plants or algae undergoing alternation of generations a haploid cell produced in the sporophyte by meiosis the spore can divide by mitosis to develop into a multicellular haploid individual the gametophyte without fusing with another cell 14 Gametophyte in organisms Plants and some algae that have alternation of generations the multicellular haploid form that produces haploid gametes by mitosis the haploid gametes unite and develop into sporophytes 15 Sporophyte in plants and some algae that undergo alternation of generations the multicellular diploid form that result from the union of gametes the sporophyte produces haploid spores by meiosis that develop into gametophytes Alternation of Generations Animals are composed of almost entirely diploid somatic cells They undergo mitosis to grow or for any repairs needed to their bodies They undergo meiosis only when producing gametes sperm or egg which are haploid Through fertilization usually internal one gamete from a male the sperm will combine with the egg from a female to create a diploid zygote This zygote then undergoes repeated cell division cleavage and slowly becomes a fetus after undergoing blastulation and gastrulation When this organism is born it may need to go through a maturation period a process known as metamorphosis when the animal becomes sexually mature and often morphologically different from its sexually immature self This organism is then able to produce its own gametes and fertilize another organism of the same species to continue the cycle Plants undergo a process known as alternation of generations A multicellular diploid plant a sporophyte will produce haploid cells called spores through meiosis These spores however do not combine with other spores to create a diploid organism as in animals They divide through mitosis to create a multicellular haploid stage where it is known as the gametophyte Gametophytes undergo mitosis to produce haploid gametes which then fuse with other gametes to create a haploid organism This haploid organism then divides through mitosis to become to the original sporophyte In fungi gametes combine to produce a diploid zygote However this zygote does not undergo mitosis and instead produces haploid cells through meiosis These haploid cells then undergo mitosis to produce either unicellular offspring or a haploid multicellular organism This organism then divides via mitosis to produce gametes which then fuse with another to form the diploid zygote The unicellular zygote is the only diploid stage found in fungi Lecture 12 Meiosis Understand that meiosis produces haploid daughter cells by separating homologous pairs of chromosomes so that one homolog goes to each cell Know that meiosis consists of two stages meiosis I and meiosis II Know that the end product of meiosis is 4 haploid cells Know that homologous chromosomes are separated in meiosis I Know that sister chromatids are separated in meiosis II Know the names of the stages of meiosis and what happens in each Understand that the pairing of homologs and crossing over both occur in Understand that both the random assortment of homologs into daughter cells and the process of crossing over result in genetically variable gametes Know the differences between mitosis and meiosis Know that special molecules prevent the separation of sister chromatids in prophase I anaphase I Vocab 1 Synapsis during Prophase 1 state in which paired homologs become physically connected to each other by zipper like protein structure synaptonemal complex state in which crossing over occurs 2 Crossing over genetic rearrangement b w non sister chromatids involving exchange of corresponding segments of DNA molecules occurs during Prophase 1 and increases variation 3 Chiasma exists at the point where a crossover has occurred hold homologs together as spindle forms 4 Meiosis 1 separates homologous chromosomes includes crossing over results in 2
View Full Document
Unlocking...