Chapter 08 - Chapter8LectureOutline Introduction...

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Chapter 8 Lecture Outline Introduction Rain Forest Rescue A. Introduce the general topics of reproduction, genetics, and inheritance, perhaps tracing the pedagogical development of the chapters in this unit. B. A life cycle is the sequence of life forms (and the processes forming them) from one generation to the next. A life cycle can be divided into two phases: Stage 1: development, from a fertilized egg to an adult Stage 2: reproduction, formation of new individuals from preexisting ones, which occurs through fertilization of an egg with a sperm. C. Sexual reproduction involves passing traits from two parents to the next generation. D. Asexual reproduction involves passing traits from only one parent to the next generation. E. A complete set of the heritable material in a cell is called a genome. Most cells contain two complete sets. Cells involved in sexual reproduction carry only one set. NOTE: There are two conflicting events in the whole life cycle progression: How, during reproduction, are faithful copies of organisms assured? How, during development, are subtle changes to the cells of a multicellular organism introduced? I. Connections Between Cell Division and Reproduction Module 8.1 Like begets like, more or less. A. This is strictly true only for organisms reproducing asexually. B. Single-celled organisms, like amoebas, can reproduce asexually by dividing in two. Each daughter cell receives an identical copy of the parent’s genes (Figure 8.1A). Genes are contained in the chromosomes, which are composed of DNA. C. For multicellular organisms (and many single-celled organisms), the offspring are not genetically identical to the parents, but each is a unique combination of the traits of both parents (Figure 8.1B). D. Breeders of domestic plants and animals manipulate sexual reproduction by selecting offspring that exhibit certain desired traits. In doing so, the breeders reduce the variability of the breed’s population of individuals. NOTE: You might want to discuss the ethics of selective breeding as well as the impact of reduced variability on a population’s survivorship. For example, some species have reduced genetic variability due to being pushed to the verge of extinction by human behaviors, as discussed in the opening essay. Preview: Observations of the work of breeders were part of the data Charles Darwin used in developing the theory of natural selection (Module 13.2). Module 8.2 Cells arise only from preexisting cells. A. This principle was formulated in 1858 by German physician Rudolf Virchow.
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B. Cell reproduction is called cell division. C. Cell division has two major roles. It enables a fertilized egg to develop through various embryonic stages, for an embryo to develop into an adult organism and to replace cells that have died from normal use or injury. It ensures the continuity from generation to generation; it is the basis of both asexual reproduction and sperm and egg formation in sexual reproduction. Module 8.3
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This note was uploaded on 03/10/2011 for the course BIOL 10 taught by Professor Kite during the Spring '11 term at Laney College.

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Chapter 08 - Chapter8LectureOutline Introduction...

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