Bio 1201 Chapter 13 -

Bio 1201 Chapter 13 - - C CHAPTER 13 MEIOSIS AND SEXUAL...

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C CHAPTER 13 MEIOSIS AND SEXUAL LIFE CYCLES Emergent property – passing genes to the next generation During meiosis I, which event does not cause variation Random fusion of gametes – does not happens in meiosis Crossing over Random alignment of tetrads I. Reproduction is an emergent property associated with life. The reproduction of an organism is a consequence of heredity. A. Heredity – continuity of biological traits from one generation to the next 1. Results from the transmission of genes 2. When individuals share similar genes (e.g., offspring, siblings, etc.) they often resemble each other. This sharing of genes automatically causes some resemblance issues. B. Variation – inherited differences among individuals of the same species; variation shows up automatically 1. While offspring resemble e their parents and siblings there are still some differences. 2. Some of these similarities and differences are studied using genetics . C. Genetics – scientific study of heredity and variation II. Offspring acquire genes from parents by inheriting sets of chromosomes Our genome is built by chromosomes Genome Chromosomes Chromatin & Genes DNA + Proteins A. Genes – units of hereditary information that are made up of DNA and are located on chromosomes 1. Specific sequences of nucleotides containing genetic information 2. Most genes code for proteins 3. Each chromosome contains hundreds or thousands of genes. 4. Each gene is in a specific region or locus in the chromosomes B. Locus Sexual Reproduction and the Role of Meiosis - 13.1.1 I. A Comparison of asexual and sexual reproduction A. Asexual reproduction – involves only one parent. Produces genetically identical offspring – Pro. cells B. Sexual reproduction – involves two parents and gives rise to offspring with unique combinations of the genes inherited from two parents – Euk. cells ASEXUAL REPRODUCTION SEXUAL REPRODUCTION Only one parent Two parents give rise to offspring Single parent passes on all its genes Each parent passes on half its genes Results in a genetically identical offspring or clone Offspring have a unique combination of genes inherited from both parents. Rare genetic differences in offspring are the result of DNA changes, or mutations Greater genetic variation with offspring being genetically different from their parents and siblings C. Clone – lineage of genetically identical individuals D. Mutation – rare change in the DNA of the genes that creates genetic diversity II. Fertilization and meiosis alternate in sexual life cycles (has to occur) Meoisis – get from a diploid to haploid The human life cycle follows the basic pattern shared by all sexually reproducing organisms. Life cycle (see fig. 13.5) – series of events, which occur between the start of one generation to the start of the next.
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This note was uploaded on 03/19/2010 for the course BIOL 1201 taught by Professor Wishtichusen during the Fall '07 term at LSU.

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Bio 1201 Chapter 13 - - C CHAPTER 13 MEIOSIS AND SEXUAL...

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