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KEY CONCEPT Independent assortment and crossing over during meiosis result in genetic diversity. Sexual reproduction creates unique combinations of genes. Sexual reproduction creates unique combination of genes. independent assortment of chromosomes in meiosis random fertilization of gametes
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KEY CONCEPT Independent assortment and crossing over during meiosis result in genetic diversity.
Sexual reproduction creates unique combinations of genes. • Sexual reproduction creates unique combination of genes. • independent assortment of chromosomes in meiosis • random fertilization of gametes • Unique phenotypes may give a reproductive advantage to some organisms.
Crossing over during meiosis increases genetic diversity. • Crossing over is the exchange of chromosome segments between homologous chromosomes. • occurs during prophase I of meiosis I • results in new combinations of genes
Chromosomes contain many genes. • The farther apart two genes are located on a chromosome, the more likely they are to be separated by crossing over. • Genes located close together on a chromosome tend to be inherited together, which is called genetic linkage. • Genetic linkage allows the distance between two genes to be calculated.
parent cell DNA duplicates cell begins to divide daughter cells Binary fission is similar in function to mitosis. • Asexual reproduction is the creation of offspring from a single parent. • Binary fission produces two daughter cells genetically identical to the parent cell. • Binary fission occurs inprokaryotes.
Environment determines what form of reproduction is most advantageous. • Asexual reproduction is an advantage in consistently favorable conditions. • Sexual reproduction is an advantage in changing conditions.
Hydra bud Yeast Some eukaryotes reproduce through mitosis. • Budding forms a new organism from a small projection growing on the surface of the parent.
Fragmentation is the splitting of the parent into pieces that each grow into a new organism. • Vegetative reproduction forms a new plant from the modification of a stem or underground structure on the parent plant.