Lecture 23 and 24 meiosis

Lecture 23 and 24 meiosis - Lecture 23 AND 24:Meiosis and...

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Lecture 23 AND 24:Meiosis and Sexual life cycles Campbell - Chapter 13 pp 238-250 Learning objectives The objective of this lecture is to understand how meiosis accounts for both the similarities and differences among siblings at the molecular level. Compare and contrast diploid and haploid cells. Recognize the phases of meiosis from diagrams or micrographs ( Know the details of Figure 13.8 ).  Describe the changes in number, and movements of chromosomes during meiosis.   Define the relationship between homologous chromosomes and sister chromatids. Compare the timing, location, numbers of cells, chromosome numbers, and genetic outcomes of mitosis and meiosis.  Describe the molecular details of synapsis and crossing over Understand what is meant by independent assortment of chromosomes Distinguish human male and female karyotypes. Be able to draw a diagram that illustrates the relationships among the terms: chromosome, DNA, genes, chromatids,  centromeres, homologous chromosomes (homologues), and alleles.  Assigned problems: 1-10 on page 250
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Terms you should know Diploid haploid gamete somatic cell  sexual reproduction asexual reproduction maternal chromosome paternal chromosome homologous chromosome tetrad karyotype zygote fertilization independent assortment sister chromatid meiosis I meiosis II heredity gene locus synapsis chiasmata  crossing over
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HEREDITY AND GENETICS The transmission of traits from one generation to the next is called heredity. Along with inherited similarity, there is also variation. Genetics = The scientific study of heredity and inherited variation.
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There are two methods of cellular reproduction: ASEXUAL: Mitosis gives rise to two identical daughter cells SEXUAL: Two parents contribute DNA to one offspring.  That  is, a sperm and egg fuse during fertilization to give rise to a single  cell  that will develop into the offspring
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THE BIOLOGICAL QUESTION:    If the number of  chromosomes must remain constant from cell to cell, during  sexual reproduction how can sperm and egg combine to form an  offspring with the same number of chromosomes as its mother  and father, rather than twice the number? THE ANSWER:  The number of chromosomes in sperm and  egg cells (gametes) have 1/2 as many chromosomes as all the  other cells (somatic cells) in the body.   Chromosome number in gametes is reduced to half by the process  of meiosis during the sexual life cycle.
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that Occurs in Sexually Reproducing Organisms Meiosis reduces the chromosome number by half, enabling sexual  recombination to occur.    Meiosis of  diploid  (2n) cells produces  haploid (n)  daughter  cells,  which may function as gametes. 
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This note was uploaded on 11/14/2010 for the course CHE 131 taught by Professor Kerber during the Spring '08 term at SUNY Stony Brook.

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Lecture 23 and 24 meiosis - Lecture 23 AND 24:Meiosis and...

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