Biology Chapter 13

Biology Chapter 13 - Chapter 13: Meiosis and Sexual Life...

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Hereditary Similarity and Variation - Hereditary: The transmission of traits from one generation to the next - Variation: offspring differs somewhat in appearance from parents and siblings - Genetics: scientific study of hereditary and hereditary variation - The process of meiosis and fertilization maintain a species’ chromosome counting during the sexual life cycle Inheritance Genes - Genes: coded information in the form of hereditary units o Segments of DNA DNA is a polymer of four different kinds of monomers called nucleotides - Gametes are reproductive cells - During fertilization male and female gametes (egg and sperm) unite o Passing on the genes of both parents to their offspring - DNA of a eukaryotic cell is subdivided into chromosomes within the nucleus - Locus: A genes specific location along the length of a chromosome Comparison of Asexual and Sexual Reproduction - Asexual Reproduction: A single individual is the sole parent and passes copies of all its genes to its offspring o Mitotic Cell Division: DNA is copied and allocated equally to two daughter cells Genomes of the offspring are exact copies of the parent’s genome - Individual that reproduces asexually gives rise to a clone o Clone: A group of genetically identical individuals - Sexual reproduction: Two parents give rise to offspring that have unique combinations of genes inherited from the two parents Fertilization and Meiosis Alternate in Sexual Life Cycles - Life Cycle: the generation to generation sequence of stages in the reproductive history of an organism, from conception to production of its own offspring Sets of chromosomes in Human Cells - Somatic Cell: Any cell other than a gamete has 46 chromosomes - Karyotype: When images of the chromosomes are arranged in pairs, starting with the longest chromosomes - Homologous Chromosomes (homologues): Two chromosomes composing a pair have the same length, centromere position, and staining pattern - Females have a homologous pair of X chromosomes (XX) - Males have one X and one Y chromosome (XY) o X and Y chromosomes are called sex chromosomes because they determine the individual’s sex - Autosome: A chromosome that is not directly involved in determining sex, as opposed to the sex chromosome - Diploid Cell: Any cell with two chromosome sets (abbreviated 2n) o Ex) Humans have a diploid number of 46 (2n=46) - Haploid Cells: Gametes that contain a single chromosome set 23 (n=23) Behavior of Chromosome Sets in the Human Life Cycle - Fertilization: Union of Gametes, culminating in fusion of their nuclei o Result: Fertilized egg called a zygote Zygote if diploid because it contains two haploid sets of chromosomes
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This note was uploaded on 11/04/2010 for the course BIO 107 taught by Professor Abott during the Fall '09 term at UConn.

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Biology Chapter 13 - Chapter 13: Meiosis and Sexual Life...

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