bio 111-02 - How do organisms get from one cell to billions...

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How do organisms get from one cell to billions or trillions??? CELL DIVISION!! How do organisms repair themselves? CELL DIVISION!!
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What happens if cell division is uncontrolled ? Something undesirable! For example, melanoma, a type of skin cancer caused by uncontrolled growth of melanocytes.
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Cell Division Cellular reproduction is a key element of life Requires 3 things: 1) 2) 3) Process needs to be controlled Responsive to environmental conditions
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Prokaryotic cell division Prokaryotes have simple form of cell division: Is clonal: They also have a simple DNA: Chromosome must be compacted, folded to fit into the cell Complex with proteins DNA is compacted by topoisomerases
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Bacteria Divide by Binary Fission DNA must be replicated and segregated into different ends of cell prior to cell division Replication begins at unique site: Bidirectional to unique site:
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Fig. 10.1 Origin of replication Replication (bidirectional) Terminus of replication Segregation FtsZ production Septum formation
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Binary Fission Segregation once thought to be passive Replicated DNA actively partition to different ends of cell Requires specific sequences near origin Septum forms at site of ring of FtsZ protein FtsZ resembles microtubule protein tubulin involved in eukaryotic mitosis
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Fig. 11.3 Figure 10.2 Fluorescent micrograph of FtsZ protein
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Eukaryotic chromosomes Sister chromatids : Homologue : Centromere : visible constriction Short repeated DNA sequences Kinetochore: Connect chromosomes to microtubules during mitosis Cohesin : complex of proteins holding sister chromatids together
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Eukaryotic chromosomes Figure 10.7
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Problems for Eukaryotic Cells Chromosome compaction Strands of DNA are too long to fit into cell Replication and chromosome separation occur at different times Means must keep chromatids of chromosomes attached until separation Release of attachment is irreversible Cleavage of cohesin
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This note was uploaded on 02/07/2011 for the course BIO 111 taught by Professor Dr. bos during the Spring '10 term at Purdue University-West Lafayette.

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bio 111-02 - How do organisms get from one cell to billions...

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