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Lecture Biology (7th edition) - Chapter 13: Meiosis and sexual life cycles

This chapter distinguish between the following terms: somatic cell and gamete, autosome and sex chromosomes, haploid and diploid; describe the events that characterize each phase of meiosis; describe three events that occur during meiosis I but not mitosis; name and explain the three events that contribute to genetic variation in sexually reproducing organisms. | Chapter 13 Meiosis and Sexual Life Cycles Overview: Hereditary Similarity and Variation Living organisms Are distinguished by their ability to reproduce their own kind Heredity Is the transmission of traits from one generation to the next Variation Shows that offspring differ somewhat in appearance from parents and siblings Figure 13.1 Genetics Is the scientific study of heredity and hereditary variation Concept 13.1: Offspring acquire genes from parents by inheriting chromosomes Inheritance of Genes Genes Are the units of heredity Are segments of DNA Each gene in an organism’s DNA Has a specific locus on a certain chromosome We inherit One set of chromosomes from our mother and one set from our father Comparison of Asexual and Sexual Reproduction In asexual reproduction One parent produces genetically identical offspring by mitosis Figure 13.2 Parent Bud 0.5 mm In sexual reproduction Two parents give rise to offspring that have unique combinations of genes inherited from the two parents Concept 13.2: Fertilization and meiosis alternate in sexual life cycles A life cycle Is the generation-to-generation sequence of stages in the reproductive history of an organism Sets of Chromosomes in Human Cells In humans Each somatic cell has 46 chromosomes, made up of two sets One set of chromosomes comes from each parent 5 µm Pair of homologous chromosomes Centromere Sister chromatids Figure 13.3 A karyotype Is an ordered, visual representation of the chromosomes in a cell Homologous chromosomes Are the two chromosomes composing a pair Have the same characteristics May also be called autosomes Sex chromosomes Are distinct from each other in their characteristics Are represented as X and Y Determine the sex of the individual, XX being female, XY being male A diploid cell Has two sets of each of its chromosomes In a human has 46 chromosomes (2n = 46) In a cell in which DNA synthesis has occurred All the chromosomes are duplicated and thus each consists of two identical sister . | Chapter 13 Meiosis and Sexual Life Cycles Overview: Hereditary Similarity and Variation Living organisms Are distinguished by their ability to reproduce their own kind Heredity Is the transmission of traits from one generation to the next Variation Shows that offspring differ somewhat in appearance from parents and siblings Figure 13.1 Genetics Is the scientific study of heredity and hereditary variation Concept 13.1: Offspring acquire genes from parents by inheriting chromosomes Inheritance of Genes Genes Are the units of heredity Are segments of DNA Each gene in an organism’s DNA Has a specific locus on a certain chromosome We inherit One set of chromosomes from our mother and one set from our father Comparison of Asexual and Sexual Reproduction In asexual reproduction One parent produces genetically identical offspring by mitosis Figure 13.2 Parent Bud 0.5 mm In sexual reproduction Two parents give rise to offspring that have unique combinations of genes inherited from the two .