LECTURE 1.PT2

Genetics: A Conceptual Approach

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Unformatted text preview: Chapter 2 Chromosomes and Cellular Reproduction Dr. Ed Otto George Mason University Key objectives Understand differences between prokaryotic and eukaryotic cells and how they reproduce Examine structure of eukaryotic chromosomes Review the eukaryotic cell cycle Compare mitosis and meiosis Understand ways in which meiosis produces genetic variability Prokaryotic & Eukaryotic Cells Prokayotes & Eukaryotes ____________: unicellular organisms with relatively simple cell structure. - bacteria- archaea ___________: have a compartmentalized cell structure with components bounded by intracellular membranes. May be unicellular or multicellular. Structural Differences Prokayotic cells Eukaryotic cells Nucleus Absent Present Cell diameter Relatively small, from 1 - 10 um Relatively large, from 10 100 um Membrane-bounded Absent Present organelles Cytoskeleton Absent Present Differences in Genetic Characteristics _________: Usually one circular DNA molecule in prokaryotic cells; multiple linear molecules in eukaryotic cells _____: In eukaryotes, DNA is closely associated with histone proteins to form tightly packed chromosomes. The complex of DNA and histones is called _________ . DNA is not complexed with histones in bacteria chromatin Differences in Genetic Characteristics _______________: Prokaryotic cells have less DNA than eukaryotic cells. Amount of DNA varies by species. prokaryotic eukaryotic Viruses Viruses are simple structures composed of an outer protein coat surrounding nucleic acid (DNA or RNA). Viruses are neither cells nor primitive forms of life: they can only reproduce within host cells (which means they evolved after cells evolved) Both eukaryotic and prokayotic cells can host viruses. Viruses that infect bacteria are called _______________ Cell Reproduction Cell Reproduction For any cell to reproduce, three events must take place: 1.Its genetic information must be copied 1.The copies of genetic information must be separated from each other 1.The cell must divide Prokaryotic Cell Reproduction Circular chromosome is replicated- replication begins at a specific place on the bacterial chromosome, called the _____________________ Newly-replicated chromosomes move away from each other and become anchored on opposite sides of the cell A new cell wall forms between the two chromosomes, producing two new cells, each with an identical copy of the chromosome. Reproduction in bacteria = Prokaryotic Cell Reproduction Eukaryotic Cell Reproduction In eukaryotes, the presence of multiple chromosomes and a nuclear envelope requires a more complex mechanism of cellular reproduction than in prokaryotic cells Eukaryotic Chromosomes Each species has a characteristic number of chromosomes per cell (e.g. fruit flies have 8, humans 46, potatoes 48) In most eukaryotic cells, there are two sets of chromosomes: one inherited from the father and one from the mother. Cells that carry two from the mother....
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This note was uploaded on 05/06/2010 for the course BIO 311 taught by Professor Otto during the Spring '10 term at George Mason.

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LECTURE 1.PT2 - Chapter 2 Chromosomes and Cellular...

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